Mounir Ibrahim, MD

Inadequate bowel preparation (IBP) at the time of inpatient colonoscopy is common and associated with increased length of stay and cost of care.¹ The factors that contribute to IBP can be categorized into those that are modifiable and those that are nonmodifiable. While many factors have been associated with IBP, studies have been limited by small sample size or have combined inpatient/outpatient populations, thus limiting generalizability.^1-5 Moreover, most factors associated with IBP, such as socioeconomic status, male gender, increased age, and comorbidities, are nonmodifiable. No studies have explicitly focused on modifiable risk factors, such as medication use, colonoscopy timing, or assessed the potential impact of modifying these factors.

In a large, multihospital system, we examine the frequency of IBP among inpatients undergoing colonoscopy along with factors associated with IBP. We attempted to identify modifiable risk factors that were associated with IBP.

METHODS

Potential Predictors of IBP

Demographic data such as patient age, gender, ethnicity, body mass index (BMI), and insurance/payor status were obtained from the electronic health record (EHR). International Classification of Disease 9^th and 10^th revision, Clinical Modifications (ICD-9/10-CM) codes were used to obtain patient comorbidities including diabetes, coronary artery disease, heart failure, cirrhosis, gastroparesis, hypothyroidism, inflammatory bowel disease, constipation, stroke, dementia, dysphagia, and nausea/vomiting. Use of opioid medications within three days before colonoscopy was extracted from the medication administration record. These variables were chosen as biologically plausible modifiers of bowel preparation or had previously been assessed in the literature.^1-6 The name and volume, classified as 4 L (GoLytely^®) and < 4 liters (MoviPrep^®) of bowel preparation, time of day when colonoscopy was performed, solid diet the day prior to colonoscopy, type of sedation used (conscious sedation or general anesthesia), and total colonoscopy time (defined as the time from scope insertion to removal) was recorded. Hospitalization-related variables, including the number of hospitalizations in the year before the current hospitalization, the year in which the colonoscopy was performed, and the number of days from admission to colonoscopy, were also obtained from the EHR.

 

Outcome Measures

An internally validated natural language algorithm, using Structured Queried Language was used to search through colonoscopy reports to identify adequacy of bowel preparation. ProVation^® software allows the gastroenterologist to use some terms to describe bowel preparation in a drop-down menu format. In addition to the Aronchik scale (which allows the gastroenterologist to rate bowel preparation on a five-point scale: “excellent,” “good,” “fair,” “poor,” and “inadequate”) it also allows the provider to use terms such as “adequate” or “adequate to detect polyps >5 mm” as well as “unsatisfactory.”⁷ Mirroring prior literature, bowel preparation quality was classified into “adequate” and “inadequate”; “good” and “excellent” on the Aronchik scale were categorized as adequate as was the term “adequate” in any form; “fair,” “poor,” or “inadequate” on the Aronchik scale were classified as inadequate as was the term “unsatisfactory.” We evaluated the hospital length of stay (LOS) as a secondary outcome measure.

Statistical Analysis

After describing the frequency of IBP, the quality of bowel preparation (adequate vs inadequate) was compared based on the predictors described above. Categorical variables were reported as frequencies with percentages and continuous variables were reported as medians with 25^th-75^th percentile values. The significance of the difference between the proportion or median values of those who had inadequate versus adequate bowel preparation was assessed. Two-sided chi-square analysis was used to assess the significance of differences between categorical variables and the Wilcoxon Rank-Sum test was used to assess the significance of differences between continuous variables.

Multivariate logistic regression analysis was performed to assess factors associated with hospital predictors and outcomes, after adjusting for all the aforementioned factors and clustering the effect based on the endoscopist. To evaluate the potential impact of modifiable factors on IBP, we performed counterfactual analysis, in which the observed distribution was compared to a hypothetical population in which all the modifiable risk factors were optimal.

RESULTS

Overall, 8,819 patients were included in our study population. They had a median age of 64 [53-76] years; 50.5% were female and 51% had an IBP. Patient characteristics and rates of IBP are presented in Table 1.

sarvepalli0547-0408e_t1.jpg

In unadjusted analyses, with regards to modifiable factors, opiate use within three days of colonoscopy was associated with a higher rate of IBP (55.4% vs 47.3%, P <.001), as was a lower volume (<4L) bowel preparation (55.3% vs 50.4%, P = .003). IBP was less frequent when colonoscopy was performed before noon vs afternoon (50.3% vs 57.4%, P < .001), and when patients were documented to receive a clear liquid diet or nil per os vs a solid diet the day prior to colonoscopy (50.3% vs 57.4%, P < .001). Overall bowel preparation quality improved over time (Figure 1). Median LOS was five [3-11] days. Patients who had IBP on their initial colonoscopy had a LOS one day longer than patients without IBP (six days vs five days, P < .001).

sarvepalli0547-0408e_f1.jpg

Multivariate Analysis

Table 2 shows the results of the multivariate analysis. The following modifiable factors were associated with IBP: opiate used within three days of the procedure (OR 1.31; 95% CI 1.8, 1.45), having the colonoscopy performed after12:00 pm (OR, 1.25; 95% CI, 1.10, 1.41), and consuming a solid diet the day prior to the colonoscopy (OR, 1.37; 95% CI, 1.18, 1.59). However, the volume of bowel preparation was not associated with IBP. The selected nonmodifiable factors that were found to be associated with IBP included age (increment of five years; OR, 1.04; 95% CI, 1.02, 1.05), male gender (OR, 1.33; 95% CI, 1.23, 1.44), Medicare insurance (OR, 1.17; 95% CI, 1.07, 1.28), Medicaid insurance (OR, 1.34; 95% CI, 1.07, 1.28), gastroparesis (OR, 1.62; 95% CI, 1.16, 2.27), nausea/vomiting (OR 1.21; 95% CI, 1.09, 1.34), and dysphagia (OR, 1.16; 95% CI, 1.01, 1.34).

sarvepalli0547-0408e_t2.jpg

 

Potential Impact of Modifiable Variables

We conducted a counterfactual analysis based on a multivariate model to assess the impact of each modifiable risk factor on the IBP rate (Figure 1). In the included study population, 44.9% received an opiate, 39.3% had a colonoscopy after 12:00 pm, and 9.1% received solid food the day prior to the procedure. Holding all other factors constant, if all patients were not prescribed opiates within three days of the procedure a 2.9% reduction in IBP would be expected. Similarly, if all patients underwent colonoscopy before noon, a 2.1% reduction in IBP rate would be expected. A 0.7% reduction would be expected if all patients were maintained on a liquid diet or nil per os. Combined, instituting all these changes (no opiates or solid diet before colonoscopy and performing all colonoscopies before noon) would produce a 5.6% reduction in IBP rate.

DISCUSSION

In this large, multihospital cohort, IBP was documented in half (51%) of 8,819 inpatient colonoscopies performed. Nonmodifiable patient characteristics independently associated with IBP were age, male gender, white race, Medicare and Medicaid insurance, nausea/vomiting, dysphagia, and gastroparesis. Modifiable factors included not consuming opiates within three days of colonoscopy, avoidance of a solid diet the day prior to colonoscopy and performing the colonoscopy before noon. The volume of bowel preparation consumed was not associated with IBP. In a counterfactual analysis, we found that if all three modifiable factors were optimized, the predicted rate of IBP would drop to 45%.

Many studies, including our analysis, have shown significant differences between the frequency of IBP in inpatient versus outpatient bowel preparations.^8-11 Therefore, it is crucial to study IBP in these settings separately. Three single-institution studies, including a total of 898 patients, have identified risk factors for inpatient IBP. Individual studies ranged in size from 130 to 524 patients with rates of IBP ranging from 22%-57%.^1-3 They found IBP to be associated with increasing age, lower income, ASA Grade >3, diabetes, coronary artery disease (CAD), nausea or vomiting, BMI >25, and chronic constipation. Modifiable factors included opiates, afternoon procedures, and runway times >6 hours.

We also found IBP to be associated with increasing age and male gender. However, we found no association with diabetes, chronic constipation, CAD or BMI. As we were able to adjust for a wider variety of variables, it is possible that we were able to account for residual confounding better than previous studies. For example, we found that having nausea/vomiting, dysphagia, and gastroparesis was associated with IBP. Gastroparesis with associated nausea and vomiting may be the mechanism by which diabetes increases the risk for IBP. Further studies are needed to assess if interventions or alternative bowel cleansing in these patients can result in improved IBP. Finally, in contrast to studies with smaller cohorts which found that lower volume bowel preps improved IBP in the right colon,^4,12 we found no association between IBP based and volume of bowel preparation consumed. Our impact analysis suggests that avoidance of opiates for at least three days before colonoscopy, avoidance of solid diet on the day before colonoscopy and performing all colonoscopies before noon would reduce the rate of IBP by 5.6%. While at first glance this does not appear to be a significant change, from a public health perspective with thousands of inpatient colonoscopies performed every year, it is crucial. We found that IBP was associated with an increased inpatient LOS of approximately one day. Assuming an average cost of one hospital day to be $2,000,¹³ this 5.6% improvement among our almost 9,000 patients, would translate into eliminating 494 unnecessary hospital days, or approximately $1 million in savings. More importantly, this savings comes without risk to patients and would result in an improvement in quality.

The factors mentioned above may not always be amenable to modification. For example, for patients with active gastrointestinal bleeding, postponing colonoscopy by one day for the sake of maintaining a patient on a clear diet may not be feasible. Similarly, performing colonoscopies in the morning is highly dependent on endoscopy suite availability and hospital logistics. Denying opiates to patients experiencing severe pain is not ethical. In many scenarios, however, these variables could be modified, and institutional efforts to support these practices could yield considerable savings. Future prospective studies are needed to verify the real impact of these changes.

Further discussion is needed to contextualize the finding that colonoscopies scheduled in the afternoon are associated with improved bowel preparation quality. Previous research—albeit in the outpatient setting—has demonstrated 11.8 hours as the maximum upper time limit for the time elapsed between the end of bowel preparation to colonoscopy.¹⁴ Another study found an inverse relationship between the quality of bowel preparation and the time after completion of the bowel preparation.¹⁵ This makes sense from a physiological perspective as delaying the time between completion of bowel preparation, and the procedure allows chyme from the small intestine to reaccumulate in the colon. Anecdotally, at our institution as well as at many others, the bowel preparations are ordered to start in the evening to allow the consumption of complete bowel preparation by midnight. As a result of this practice, only patients who have their colonoscopies scheduled before noon fall within the optimal period of 11.8 hours. In the outpatient setting, the use of split preparations has led to the obliteration of the difference in the quality of bowel preparation between morning and afternoon colonoscopies.¹⁶ Prospective trials are needed to evaluate the use of split preparations to improve the quality of afternoon inpatient colonoscopies.

sarvepalli0547-0408e_f2.jpg

Few other strategies have been shown to mitigate IBP in the inpatient setting. In a small randomized controlled trial, Ergen et al. found that providing an educational booklet improved inpatient bowel preparation as measured by the Boston Bowel Preparation Scale.¹⁷ In a quasi-experimental design, Yadlapati et al. found that an automated split-dose bowel preparation resulted in decreased IBP, fewer repeated procedures, shorter LOS, and lower hospital cost.¹⁸ Our study adds to these tools by identifying three additional risk factors which could be optimized for inpatients. Because our findings are observational, they should be subjected to prospective trials. Our study also calls into question the impact of bowel preparation volume. We found no difference in the rate of IBP between low and large volume preparations. It is possible that other factors are more important than the specific preparation employed. Information regarding the use of split preparations or same day preparations was not recorded and therefore not assessed in our study.

Interestingly, we found that IBP declined substantially in 2014 and continued to decline after that. The year was the most influential risk factor for IBP (on par with gastroparesis). The reason for this is unclear, as rates of our modifiable risk factors did not differ substantially by year. Other possibilities include improved access (including weekend access) to endoscopy coinciding with the development of a new endoscopy facility and use of integrated irrigation pump system instead of the use of manual syringes for flushing.

Our study has many strengths. It is by far the most extensive study of bowel preparation quality in inpatients to date and the only one that has included patient, procedural and bowel preparation characteristics. The study also has several significant limitations. This is a single center study, which could limit generalizability. Nonetheless, it was conducted within a health system with multiple hospitals in different parts of the United States (Ohio and Florida) and included a broad population mix with differing levels of acuity. The retrospective nature of the assessment precludes establishing causation. However, we mitigated confounding by adjusting for a wide variety of factors, and there is a plausible physiological mechanism for each of the factors we studied. Also, the retrospective nature of our study predisposes our data to omissions and misrepresentations during the documentation process. This is especially true with the use of ICD codes.¹⁹ Inaccuracies in coding are likely to bias toward the null, so observed associations may be an underestimate of the true association.

Our inability to ascertain if a patient completed the prescribed bowel preparation limited our ability to detect what may be a significant risk factor. Lastly, while clinically relevant, the Aronchik scale used to identify adequate from IBP has never been validated though it is frequently utilized and cited in the bowel preparation literature.²⁰

 

CONCLUSIONS

In this large retrospective study evaluating bowel preparation quality in inpatients undergoing colonoscopy, we found that more than half of the patients have IBP and that IBP was associated with an extra day of hospitalization. Our study identifies those patients at highest risk and identifies modifiable risk factors for IBP. Specifically, we found that abstinence from opiates or solid diet before the colonoscopy, along with performing colonoscopies before noon were associated with improved outcomes. Prospective studies are needed to confirm the effects of these interventions on bowel preparation quality.

Disclosures

Carol A Burke, MD has received research funding from Ferring Pharmaceuticals. Other authors have no conflicts of interest to disclose.

Inadequate bowel preparation (IBP) at the time of inpatient colonoscopy is common and associated with increased length of stay and cost of care.¹ The factors that contribute to IBP can be categorized into those that are modifiable and those that are nonmodifiable. While many factors have been associated with IBP, studies have been limited by small sample size or have combined inpatient/outpatient populations, thus limiting generalizability.^1-5 Moreover, most factors associated with IBP, such as socioeconomic status, male gender, increased age, and comorbidities, are nonmodifiable. No studies have explicitly focused on modifiable risk factors, such as medication use, colonoscopy timing, or assessed the potential impact of modifying these factors.

In a large, multihospital system, we examine the frequency of IBP among inpatients undergoing colonoscopy along with factors associated with IBP. We attempted to identify modifiable risk factors that were associated with IBP.

METHODS

Potential Predictors of IBP

Demographic data such as patient age, gender, ethnicity, body mass index (BMI), and insurance/payor status were obtained from the electronic health record (EHR). International Classification of Disease 9^th and 10^th revision, Clinical Modifications (ICD-9/10-CM) codes were used to obtain patient comorbidities including diabetes, coronary artery disease, heart failure, cirrhosis, gastroparesis, hypothyroidism, inflammatory bowel disease, constipation, stroke, dementia, dysphagia, and nausea/vomiting. Use of opioid medications within three days before colonoscopy was extracted from the medication administration record. These variables were chosen as biologically plausible modifiers of bowel preparation or had previously been assessed in the literature.^1-6 The name and volume, classified as 4 L (GoLytely^®) and < 4 liters (MoviPrep^®) of bowel preparation, time of day when colonoscopy was performed, solid diet the day prior to colonoscopy, type of sedation used (conscious sedation or general anesthesia), and total colonoscopy time (defined as the time from scope insertion to removal) was recorded. Hospitalization-related variables, including the number of hospitalizations in the year before the current hospitalization, the year in which the colonoscopy was performed, and the number of days from admission to colonoscopy, were also obtained from the EHR.

 

Outcome Measures

An internally validated natural language algorithm, using Structured Queried Language was used to search through colonoscopy reports to identify adequacy of bowel preparation. ProVation^® software allows the gastroenterologist to use some terms to describe bowel preparation in a drop-down menu format. In addition to the Aronchik scale (which allows the gastroenterologist to rate bowel preparation on a five-point scale: “excellent,” “good,” “fair,” “poor,” and “inadequate”) it also allows the provider to use terms such as “adequate” or “adequate to detect polyps >5 mm” as well as “unsatisfactory.”⁷ Mirroring prior literature, bowel preparation quality was classified into “adequate” and “inadequate”; “good” and “excellent” on the Aronchik scale were categorized as adequate as was the term “adequate” in any form; “fair,” “poor,” or “inadequate” on the Aronchik scale were classified as inadequate as was the term “unsatisfactory.” We evaluated the hospital length of stay (LOS) as a secondary outcome measure.

Statistical Analysis

After describing the frequency of IBP, the quality of bowel preparation (adequate vs inadequate) was compared based on the predictors described above. Categorical variables were reported as frequencies with percentages and continuous variables were reported as medians with 25^th-75^th percentile values. The significance of the difference between the proportion or median values of those who had inadequate versus adequate bowel preparation was assessed. Two-sided chi-square analysis was used to assess the significance of differences between categorical variables and the Wilcoxon Rank-Sum test was used to assess the significance of differences between continuous variables.

Multivariate logistic regression analysis was performed to assess factors associated with hospital predictors and outcomes, after adjusting for all the aforementioned factors and clustering the effect based on the endoscopist. To evaluate the potential impact of modifiable factors on IBP, we performed counterfactual analysis, in which the observed distribution was compared to a hypothetical population in which all the modifiable risk factors were optimal.

RESULTS

Overall, 8,819 patients were included in our study population. They had a median age of 64 [53-76] years; 50.5% were female and 51% had an IBP. Patient characteristics and rates of IBP are presented in Table 1.

sarvepalli0547-0408e_t1.jpg

In unadjusted analyses, with regards to modifiable factors, opiate use within three days of colonoscopy was associated with a higher rate of IBP (55.4% vs 47.3%, P <.001), as was a lower volume (<4L) bowel preparation (55.3% vs 50.4%, P = .003). IBP was less frequent when colonoscopy was performed before noon vs afternoon (50.3% vs 57.4%, P < .001), and when patients were documented to receive a clear liquid diet or nil per os vs a solid diet the day prior to colonoscopy (50.3% vs 57.4%, P < .001). Overall bowel preparation quality improved over time (Figure 1). Median LOS was five [3-11] days. Patients who had IBP on their initial colonoscopy had a LOS one day longer than patients without IBP (six days vs five days, P < .001).

sarvepalli0547-0408e_f1.jpg

Multivariate Analysis

Table 2 shows the results of the multivariate analysis. The following modifiable factors were associated with IBP: opiate used within three days of the procedure (OR 1.31; 95% CI 1.8, 1.45), having the colonoscopy performed after12:00 pm (OR, 1.25; 95% CI, 1.10, 1.41), and consuming a solid diet the day prior to the colonoscopy (OR, 1.37; 95% CI, 1.18, 1.59). However, the volume of bowel preparation was not associated with IBP. The selected nonmodifiable factors that were found to be associated with IBP included age (increment of five years; OR, 1.04; 95% CI, 1.02, 1.05), male gender (OR, 1.33; 95% CI, 1.23, 1.44), Medicare insurance (OR, 1.17; 95% CI, 1.07, 1.28), Medicaid insurance (OR, 1.34; 95% CI, 1.07, 1.28), gastroparesis (OR, 1.62; 95% CI, 1.16, 2.27), nausea/vomiting (OR 1.21; 95% CI, 1.09, 1.34), and dysphagia (OR, 1.16; 95% CI, 1.01, 1.34).

sarvepalli0547-0408e_t2.jpg

 

Potential Impact of Modifiable Variables

We conducted a counterfactual analysis based on a multivariate model to assess the impact of each modifiable risk factor on the IBP rate (Figure 1). In the included study population, 44.9% received an opiate, 39.3% had a colonoscopy after 12:00 pm, and 9.1% received solid food the day prior to the procedure. Holding all other factors constant, if all patients were not prescribed opiates within three days of the procedure a 2.9% reduction in IBP would be expected. Similarly, if all patients underwent colonoscopy before noon, a 2.1% reduction in IBP rate would be expected. A 0.7% reduction would be expected if all patients were maintained on a liquid diet or nil per os. Combined, instituting all these changes (no opiates or solid diet before colonoscopy and performing all colonoscopies before noon) would produce a 5.6% reduction in IBP rate.

DISCUSSION

In this large, multihospital cohort, IBP was documented in half (51%) of 8,819 inpatient colonoscopies performed. Nonmodifiable patient characteristics independently associated with IBP were age, male gender, white race, Medicare and Medicaid insurance, nausea/vomiting, dysphagia, and gastroparesis. Modifiable factors included not consuming opiates within three days of colonoscopy, avoidance of a solid diet the day prior to colonoscopy and performing the colonoscopy before noon. The volume of bowel preparation consumed was not associated with IBP. In a counterfactual analysis, we found that if all three modifiable factors were optimized, the predicted rate of IBP would drop to 45%.

Many studies, including our analysis, have shown significant differences between the frequency of IBP in inpatient versus outpatient bowel preparations.^8-11 Therefore, it is crucial to study IBP in these settings separately. Three single-institution studies, including a total of 898 patients, have identified risk factors for inpatient IBP. Individual studies ranged in size from 130 to 524 patients with rates of IBP ranging from 22%-57%.^1-3 They found IBP to be associated with increasing age, lower income, ASA Grade >3, diabetes, coronary artery disease (CAD), nausea or vomiting, BMI >25, and chronic constipation. Modifiable factors included opiates, afternoon procedures, and runway times >6 hours.

We also found IBP to be associated with increasing age and male gender. However, we found no association with diabetes, chronic constipation, CAD or BMI. As we were able to adjust for a wider variety of variables, it is possible that we were able to account for residual confounding better than previous studies. For example, we found that having nausea/vomiting, dysphagia, and gastroparesis was associated with IBP. Gastroparesis with associated nausea and vomiting may be the mechanism by which diabetes increases the risk for IBP. Further studies are needed to assess if interventions or alternative bowel cleansing in these patients can result in improved IBP. Finally, in contrast to studies with smaller cohorts which found that lower volume bowel preps improved IBP in the right colon,^4,12 we found no association between IBP based and volume of bowel preparation consumed. Our impact analysis suggests that avoidance of opiates for at least three days before colonoscopy, avoidance of solid diet on the day before colonoscopy and performing all colonoscopies before noon would reduce the rate of IBP by 5.6%. While at first glance this does not appear to be a significant change, from a public health perspective with thousands of inpatient colonoscopies performed every year, it is crucial. We found that IBP was associated with an increased inpatient LOS of approximately one day. Assuming an average cost of one hospital day to be $2,000,¹³ this 5.6% improvement among our almost 9,000 patients, would translate into eliminating 494 unnecessary hospital days, or approximately $1 million in savings. More importantly, this savings comes without risk to patients and would result in an improvement in quality.

The factors mentioned above may not always be amenable to modification. For example, for patients with active gastrointestinal bleeding, postponing colonoscopy by one day for the sake of maintaining a patient on a clear diet may not be feasible. Similarly, performing colonoscopies in the morning is highly dependent on endoscopy suite availability and hospital logistics. Denying opiates to patients experiencing severe pain is not ethical. In many scenarios, however, these variables could be modified, and institutional efforts to support these practices could yield considerable savings. Future prospective studies are needed to verify the real impact of these changes.

Further discussion is needed to contextualize the finding that colonoscopies scheduled in the afternoon are associated with improved bowel preparation quality. Previous research—albeit in the outpatient setting—has demonstrated 11.8 hours as the maximum upper time limit for the time elapsed between the end of bowel preparation to colonoscopy.¹⁴ Another study found an inverse relationship between the quality of bowel preparation and the time after completion of the bowel preparation.¹⁵ This makes sense from a physiological perspective as delaying the time between completion of bowel preparation, and the procedure allows chyme from the small intestine to reaccumulate in the colon. Anecdotally, at our institution as well as at many others, the bowel preparations are ordered to start in the evening to allow the consumption of complete bowel preparation by midnight. As a result of this practice, only patients who have their colonoscopies scheduled before noon fall within the optimal period of 11.8 hours. In the outpatient setting, the use of split preparations has led to the obliteration of the difference in the quality of bowel preparation between morning and afternoon colonoscopies.¹⁶ Prospective trials are needed to evaluate the use of split preparations to improve the quality of afternoon inpatient colonoscopies.

sarvepalli0547-0408e_f2.jpg

Few other strategies have been shown to mitigate IBP in the inpatient setting. In a small randomized controlled trial, Ergen et al. found that providing an educational booklet improved inpatient bowel preparation as measured by the Boston Bowel Preparation Scale.¹⁷ In a quasi-experimental design, Yadlapati et al. found that an automated split-dose bowel preparation resulted in decreased IBP, fewer repeated procedures, shorter LOS, and lower hospital cost.¹⁸ Our study adds to these tools by identifying three additional risk factors which could be optimized for inpatients. Because our findings are observational, they should be subjected to prospective trials. Our study also calls into question the impact of bowel preparation volume. We found no difference in the rate of IBP between low and large volume preparations. It is possible that other factors are more important than the specific preparation employed. Information regarding the use of split preparations or same day preparations was not recorded and therefore not assessed in our study.

Interestingly, we found that IBP declined substantially in 2014 and continued to decline after that. The year was the most influential risk factor for IBP (on par with gastroparesis). The reason for this is unclear, as rates of our modifiable risk factors did not differ substantially by year. Other possibilities include improved access (including weekend access) to endoscopy coinciding with the development of a new endoscopy facility and use of integrated irrigation pump system instead of the use of manual syringes for flushing.

Our study has many strengths. It is by far the most extensive study of bowel preparation quality in inpatients to date and the only one that has included patient, procedural and bowel preparation characteristics. The study also has several significant limitations. This is a single center study, which could limit generalizability. Nonetheless, it was conducted within a health system with multiple hospitals in different parts of the United States (Ohio and Florida) and included a broad population mix with differing levels of acuity. The retrospective nature of the assessment precludes establishing causation. However, we mitigated confounding by adjusting for a wide variety of factors, and there is a plausible physiological mechanism for each of the factors we studied. Also, the retrospective nature of our study predisposes our data to omissions and misrepresentations during the documentation process. This is especially true with the use of ICD codes.¹⁹ Inaccuracies in coding are likely to bias toward the null, so observed associations may be an underestimate of the true association.

Our inability to ascertain if a patient completed the prescribed bowel preparation limited our ability to detect what may be a significant risk factor. Lastly, while clinically relevant, the Aronchik scale used to identify adequate from IBP has never been validated though it is frequently utilized and cited in the bowel preparation literature.²⁰

 

CONCLUSIONS

In this large retrospective study evaluating bowel preparation quality in inpatients undergoing colonoscopy, we found that more than half of the patients have IBP and that IBP was associated with an extra day of hospitalization. Our study identifies those patients at highest risk and identifies modifiable risk factors for IBP. Specifically, we found that abstinence from opiates or solid diet before the colonoscopy, along with performing colonoscopies before noon were associated with improved outcomes. Prospective studies are needed to confirm the effects of these interventions on bowel preparation quality.

Disclosures

Carol A Burke, MD has received research funding from Ferring Pharmaceuticals. Other authors have no conflicts of interest to disclose.

Inadequate bowel preparation (IBP) at the time of inpatient colonoscopy is common and associated with increased length of stay and cost of care.¹ The factors that contribute to IBP can be categorized into those that are modifiable and those that are nonmodifiable. While many factors have been associated with IBP, studies have been limited by small sample size or have combined inpatient/outpatient populations, thus limiting generalizability.^1-5 Moreover, most factors associated with IBP, such as socioeconomic status, male gender, increased age, and comorbidities, are nonmodifiable. No studies have explicitly focused on modifiable risk factors, such as medication use, colonoscopy timing, or assessed the potential impact of modifying these factors.

In a large, multihospital system, we examine the frequency of IBP among inpatients undergoing colonoscopy along with factors associated with IBP. We attempted to identify modifiable risk factors that were associated with IBP.

METHODS

Potential Predictors of IBP

Demographic data such as patient age, gender, ethnicity, body mass index (BMI), and insurance/payor status were obtained from the electronic health record (EHR). International Classification of Disease 9^th and 10^th revision, Clinical Modifications (ICD-9/10-CM) codes were used to obtain patient comorbidities including diabetes, coronary artery disease, heart failure, cirrhosis, gastroparesis, hypothyroidism, inflammatory bowel disease, constipation, stroke, dementia, dysphagia, and nausea/vomiting. Use of opioid medications within three days before colonoscopy was extracted from the medication administration record. These variables were chosen as biologically plausible modifiers of bowel preparation or had previously been assessed in the literature.^1-6 The name and volume, classified as 4 L (GoLytely^®) and < 4 liters (MoviPrep^®) of bowel preparation, time of day when colonoscopy was performed, solid diet the day prior to colonoscopy, type of sedation used (conscious sedation or general anesthesia), and total colonoscopy time (defined as the time from scope insertion to removal) was recorded. Hospitalization-related variables, including the number of hospitalizations in the year before the current hospitalization, the year in which the colonoscopy was performed, and the number of days from admission to colonoscopy, were also obtained from the EHR.

 

Outcome Measures

An internally validated natural language algorithm, using Structured Queried Language was used to search through colonoscopy reports to identify adequacy of bowel preparation. ProVation^® software allows the gastroenterologist to use some terms to describe bowel preparation in a drop-down menu format. In addition to the Aronchik scale (which allows the gastroenterologist to rate bowel preparation on a five-point scale: “excellent,” “good,” “fair,” “poor,” and “inadequate”) it also allows the provider to use terms such as “adequate” or “adequate to detect polyps >5 mm” as well as “unsatisfactory.”⁷ Mirroring prior literature, bowel preparation quality was classified into “adequate” and “inadequate”; “good” and “excellent” on the Aronchik scale were categorized as adequate as was the term “adequate” in any form; “fair,” “poor,” or “inadequate” on the Aronchik scale were classified as inadequate as was the term “unsatisfactory.” We evaluated the hospital length of stay (LOS) as a secondary outcome measure.

Statistical Analysis

After describing the frequency of IBP, the quality of bowel preparation (adequate vs inadequate) was compared based on the predictors described above. Categorical variables were reported as frequencies with percentages and continuous variables were reported as medians with 25^th-75^th percentile values. The significance of the difference between the proportion or median values of those who had inadequate versus adequate bowel preparation was assessed. Two-sided chi-square analysis was used to assess the significance of differences between categorical variables and the Wilcoxon Rank-Sum test was used to assess the significance of differences between continuous variables.

Multivariate logistic regression analysis was performed to assess factors associated with hospital predictors and outcomes, after adjusting for all the aforementioned factors and clustering the effect based on the endoscopist. To evaluate the potential impact of modifiable factors on IBP, we performed counterfactual analysis, in which the observed distribution was compared to a hypothetical population in which all the modifiable risk factors were optimal.

RESULTS

Overall, 8,819 patients were included in our study population. They had a median age of 64 [53-76] years; 50.5% were female and 51% had an IBP. Patient characteristics and rates of IBP are presented in Table 1.

sarvepalli0547-0408e_t1.jpg

In unadjusted analyses, with regards to modifiable factors, opiate use within three days of colonoscopy was associated with a higher rate of IBP (55.4% vs 47.3%, P <.001), as was a lower volume (<4L) bowel preparation (55.3% vs 50.4%, P = .003). IBP was less frequent when colonoscopy was performed before noon vs afternoon (50.3% vs 57.4%, P < .001), and when patients were documented to receive a clear liquid diet or nil per os vs a solid diet the day prior to colonoscopy (50.3% vs 57.4%, P < .001). Overall bowel preparation quality improved over time (Figure 1). Median LOS was five [3-11] days. Patients who had IBP on their initial colonoscopy had a LOS one day longer than patients without IBP (six days vs five days, P < .001).

sarvepalli0547-0408e_f1.jpg

Multivariate Analysis

Table 2 shows the results of the multivariate analysis. The following modifiable factors were associated with IBP: opiate used within three days of the procedure (OR 1.31; 95% CI 1.8, 1.45), having the colonoscopy performed after12:00 pm (OR, 1.25; 95% CI, 1.10, 1.41), and consuming a solid diet the day prior to the colonoscopy (OR, 1.37; 95% CI, 1.18, 1.59). However, the volume of bowel preparation was not associated with IBP. The selected nonmodifiable factors that were found to be associated with IBP included age (increment of five years; OR, 1.04; 95% CI, 1.02, 1.05), male gender (OR, 1.33; 95% CI, 1.23, 1.44), Medicare insurance (OR, 1.17; 95% CI, 1.07, 1.28), Medicaid insurance (OR, 1.34; 95% CI, 1.07, 1.28), gastroparesis (OR, 1.62; 95% CI, 1.16, 2.27), nausea/vomiting (OR 1.21; 95% CI, 1.09, 1.34), and dysphagia (OR, 1.16; 95% CI, 1.01, 1.34).

sarvepalli0547-0408e_t2.jpg

 

Potential Impact of Modifiable Variables

We conducted a counterfactual analysis based on a multivariate model to assess the impact of each modifiable risk factor on the IBP rate (Figure 1). In the included study population, 44.9% received an opiate, 39.3% had a colonoscopy after 12:00 pm, and 9.1% received solid food the day prior to the procedure. Holding all other factors constant, if all patients were not prescribed opiates within three days of the procedure a 2.9% reduction in IBP would be expected. Similarly, if all patients underwent colonoscopy before noon, a 2.1% reduction in IBP rate would be expected. A 0.7% reduction would be expected if all patients were maintained on a liquid diet or nil per os. Combined, instituting all these changes (no opiates or solid diet before colonoscopy and performing all colonoscopies before noon) would produce a 5.6% reduction in IBP rate.

DISCUSSION

In this large, multihospital cohort, IBP was documented in half (51%) of 8,819 inpatient colonoscopies performed. Nonmodifiable patient characteristics independently associated with IBP were age, male gender, white race, Medicare and Medicaid insurance, nausea/vomiting, dysphagia, and gastroparesis. Modifiable factors included not consuming opiates within three days of colonoscopy, avoidance of a solid diet the day prior to colonoscopy and performing the colonoscopy before noon. The volume of bowel preparation consumed was not associated with IBP. In a counterfactual analysis, we found that if all three modifiable factors were optimized, the predicted rate of IBP would drop to 45%.

Many studies, including our analysis, have shown significant differences between the frequency of IBP in inpatient versus outpatient bowel preparations.^8-11 Therefore, it is crucial to study IBP in these settings separately. Three single-institution studies, including a total of 898 patients, have identified risk factors for inpatient IBP. Individual studies ranged in size from 130 to 524 patients with rates of IBP ranging from 22%-57%.^1-3 They found IBP to be associated with increasing age, lower income, ASA Grade >3, diabetes, coronary artery disease (CAD), nausea or vomiting, BMI >25, and chronic constipation. Modifiable factors included opiates, afternoon procedures, and runway times >6 hours.

We also found IBP to be associated with increasing age and male gender. However, we found no association with diabetes, chronic constipation, CAD or BMI. As we were able to adjust for a wider variety of variables, it is possible that we were able to account for residual confounding better than previous studies. For example, we found that having nausea/vomiting, dysphagia, and gastroparesis was associated with IBP. Gastroparesis with associated nausea and vomiting may be the mechanism by which diabetes increases the risk for IBP. Further studies are needed to assess if interventions or alternative bowel cleansing in these patients can result in improved IBP. Finally, in contrast to studies with smaller cohorts which found that lower volume bowel preps improved IBP in the right colon,^4,12 we found no association between IBP based and volume of bowel preparation consumed. Our impact analysis suggests that avoidance of opiates for at least three days before colonoscopy, avoidance of solid diet on the day before colonoscopy and performing all colonoscopies before noon would reduce the rate of IBP by 5.6%. While at first glance this does not appear to be a significant change, from a public health perspective with thousands of inpatient colonoscopies performed every year, it is crucial. We found that IBP was associated with an increased inpatient LOS of approximately one day. Assuming an average cost of one hospital day to be $2,000,¹³ this 5.6% improvement among our almost 9,000 patients, would translate into eliminating 494 unnecessary hospital days, or approximately $1 million in savings. More importantly, this savings comes without risk to patients and would result in an improvement in quality.

The factors mentioned above may not always be amenable to modification. For example, for patients with active gastrointestinal bleeding, postponing colonoscopy by one day for the sake of maintaining a patient on a clear diet may not be feasible. Similarly, performing colonoscopies in the morning is highly dependent on endoscopy suite availability and hospital logistics. Denying opiates to patients experiencing severe pain is not ethical. In many scenarios, however, these variables could be modified, and institutional efforts to support these practices could yield considerable savings. Future prospective studies are needed to verify the real impact of these changes.

Further discussion is needed to contextualize the finding that colonoscopies scheduled in the afternoon are associated with improved bowel preparation quality. Previous research—albeit in the outpatient setting—has demonstrated 11.8 hours as the maximum upper time limit for the time elapsed between the end of bowel preparation to colonoscopy.¹⁴ Another study found an inverse relationship between the quality of bowel preparation and the time after completion of the bowel preparation.¹⁵ This makes sense from a physiological perspective as delaying the time between completion of bowel preparation, and the procedure allows chyme from the small intestine to reaccumulate in the colon. Anecdotally, at our institution as well as at many others, the bowel preparations are ordered to start in the evening to allow the consumption of complete bowel preparation by midnight. As a result of this practice, only patients who have their colonoscopies scheduled before noon fall within the optimal period of 11.8 hours. In the outpatient setting, the use of split preparations has led to the obliteration of the difference in the quality of bowel preparation between morning and afternoon colonoscopies.¹⁶ Prospective trials are needed to evaluate the use of split preparations to improve the quality of afternoon inpatient colonoscopies.

sarvepalli0547-0408e_f2.jpg

Few other strategies have been shown to mitigate IBP in the inpatient setting. In a small randomized controlled trial, Ergen et al. found that providing an educational booklet improved inpatient bowel preparation as measured by the Boston Bowel Preparation Scale.¹⁷ In a quasi-experimental design, Yadlapati et al. found that an automated split-dose bowel preparation resulted in decreased IBP, fewer repeated procedures, shorter LOS, and lower hospital cost.¹⁸ Our study adds to these tools by identifying three additional risk factors which could be optimized for inpatients. Because our findings are observational, they should be subjected to prospective trials. Our study also calls into question the impact of bowel preparation volume. We found no difference in the rate of IBP between low and large volume preparations. It is possible that other factors are more important than the specific preparation employed. Information regarding the use of split preparations or same day preparations was not recorded and therefore not assessed in our study.

Interestingly, we found that IBP declined substantially in 2014 and continued to decline after that. The year was the most influential risk factor for IBP (on par with gastroparesis). The reason for this is unclear, as rates of our modifiable risk factors did not differ substantially by year. Other possibilities include improved access (including weekend access) to endoscopy coinciding with the development of a new endoscopy facility and use of integrated irrigation pump system instead of the use of manual syringes for flushing.

Our study has many strengths. It is by far the most extensive study of bowel preparation quality in inpatients to date and the only one that has included patient, procedural and bowel preparation characteristics. The study also has several significant limitations. This is a single center study, which could limit generalizability. Nonetheless, it was conducted within a health system with multiple hospitals in different parts of the United States (Ohio and Florida) and included a broad population mix with differing levels of acuity. The retrospective nature of the assessment precludes establishing causation. However, we mitigated confounding by adjusting for a wide variety of factors, and there is a plausible physiological mechanism for each of the factors we studied. Also, the retrospective nature of our study predisposes our data to omissions and misrepresentations during the documentation process. This is especially true with the use of ICD codes.¹⁹ Inaccuracies in coding are likely to bias toward the null, so observed associations may be an underestimate of the true association.

Our inability to ascertain if a patient completed the prescribed bowel preparation limited our ability to detect what may be a significant risk factor. Lastly, while clinically relevant, the Aronchik scale used to identify adequate from IBP has never been validated though it is frequently utilized and cited in the bowel preparation literature.²⁰

 

CONCLUSIONS

In this large retrospective study evaluating bowel preparation quality in inpatients undergoing colonoscopy, we found that more than half of the patients have IBP and that IBP was associated with an extra day of hospitalization. Our study identifies those patients at highest risk and identifies modifiable risk factors for IBP. Specifically, we found that abstinence from opiates or solid diet before the colonoscopy, along with performing colonoscopies before noon were associated with improved outcomes. Prospective studies are needed to confirm the effects of these interventions on bowel preparation quality.

Disclosures

Carol A Burke, MD has received research funding from Ferring Pharmaceuticals. Other authors have no conflicts of interest to disclose.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

ibrahim_gallstones_t1.jpg

Multiple risk factors are associated with the development of gallstones (Table 1).

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

 

 

CLINICAL PRESENTATION OF GALLSTONES (CHOLELITHIASIS)

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

ibrahim_gallstones_t2.jpg

In any year, approximately 1% to 3% of patients with gallstones experience a gallstone-related complication.¹⁸ These complications (Table 2) can occur in patients with or without symptoms. Patients without previous symptoms from gallstones have a slightly lower 10-year cumulative risk of complications—3% to 4% vs approximately 6% in patients who have had gallstone-related symptoms.¹⁹

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

 

 

ABDOMINAL ULTRASONOGRAPHY FOR DIAGNOSIS

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

ibrahim_gallstones_t3.jpg

The management of patients with asymptomatic gallstones typically is based on the risk of developing symptoms or complications. Large cohort studies have found that patients without symptoms have about a 7% to 26% lifetime risk of developing them (Table 3).^39–46

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

 

 

Laparoscopic surgery for symptomatic gallstones

ibrahim_gallstones_f1.jpg

Patients with symptomatic gallstones are at high risk of biliary complications. Laparoscopic cholecystectomy is recommended for patients who can undergo surgery (Figure 1).⁴⁸ Oral dissolution therapy and extracorporeal shock wave lithotripsy are available for patients who cannot undergo surgery but have good gallbladder function, small radiopaque stones, and mild symptoms. Clinical management and emergency laparoscopic cholecystectomy are recommended for large pigmented or radiopaque stones. Otherwise, clinical follow-up is recommended.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

ibrahim_gallstones_f2.jpg

For patients with bile duct stones. Guidelines from the American Society for Gastrointestinal Endoscopy (ASGE) suggest that patients with an intermediate or high probability of developing choledocholithiasis should undergo preoperative or intraoperative evaluation of the common bile duct (Figure 2).³¹

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 

  ibrahim_gallstones_t4.jpg
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

ibrahim_gallstones_t1.jpg

Multiple risk factors are associated with the development of gallstones (Table 1).

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

 

 

CLINICAL PRESENTATION OF GALLSTONES (CHOLELITHIASIS)

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

ibrahim_gallstones_t2.jpg

In any year, approximately 1% to 3% of patients with gallstones experience a gallstone-related complication.¹⁸ These complications (Table 2) can occur in patients with or without symptoms. Patients without previous symptoms from gallstones have a slightly lower 10-year cumulative risk of complications—3% to 4% vs approximately 6% in patients who have had gallstone-related symptoms.¹⁹

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

 

 

ABDOMINAL ULTRASONOGRAPHY FOR DIAGNOSIS

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

ibrahim_gallstones_t3.jpg

The management of patients with asymptomatic gallstones typically is based on the risk of developing symptoms or complications. Large cohort studies have found that patients without symptoms have about a 7% to 26% lifetime risk of developing them (Table 3).^39–46

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

 

 

Laparoscopic surgery for symptomatic gallstones

ibrahim_gallstones_f1.jpg

Patients with symptomatic gallstones are at high risk of biliary complications. Laparoscopic cholecystectomy is recommended for patients who can undergo surgery (Figure 1).⁴⁸ Oral dissolution therapy and extracorporeal shock wave lithotripsy are available for patients who cannot undergo surgery but have good gallbladder function, small radiopaque stones, and mild symptoms. Clinical management and emergency laparoscopic cholecystectomy are recommended for large pigmented or radiopaque stones. Otherwise, clinical follow-up is recommended.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

ibrahim_gallstones_f2.jpg

For patients with bile duct stones. Guidelines from the American Society for Gastrointestinal Endoscopy (ASGE) suggest that patients with an intermediate or high probability of developing choledocholithiasis should undergo preoperative or intraoperative evaluation of the common bile duct (Figure 2).³¹

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 

  ibrahim_gallstones_t4.jpg
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

ibrahim_gallstones_t1.jpg

Multiple risk factors are associated with the development of gallstones (Table 1).

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

 

 

CLINICAL PRESENTATION OF GALLSTONES (CHOLELITHIASIS)

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

ibrahim_gallstones_t2.jpg

In any year, approximately 1% to 3% of patients with gallstones experience a gallstone-related complication.¹⁸ These complications (Table 2) can occur in patients with or without symptoms. Patients without previous symptoms from gallstones have a slightly lower 10-year cumulative risk of complications—3% to 4% vs approximately 6% in patients who have had gallstone-related symptoms.¹⁹

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

 

 

ABDOMINAL ULTRASONOGRAPHY FOR DIAGNOSIS

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

ibrahim_gallstones_t3.jpg

The management of patients with asymptomatic gallstones typically is based on the risk of developing symptoms or complications. Large cohort studies have found that patients without symptoms have about a 7% to 26% lifetime risk of developing them (Table 3).^39–46

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

 

 

Laparoscopic surgery for symptomatic gallstones

ibrahim_gallstones_f1.jpg

Patients with symptomatic gallstones are at high risk of biliary complications. Laparoscopic cholecystectomy is recommended for patients who can undergo surgery (Figure 1).⁴⁸ Oral dissolution therapy and extracorporeal shock wave lithotripsy are available for patients who cannot undergo surgery but have good gallbladder function, small radiopaque stones, and mild symptoms. Clinical management and emergency laparoscopic cholecystectomy are recommended for large pigmented or radiopaque stones. Otherwise, clinical follow-up is recommended.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

ibrahim_gallstones_f2.jpg

For patients with bile duct stones. Guidelines from the American Society for Gastrointestinal Endoscopy (ASGE) suggest that patients with an intermediate or high probability of developing choledocholithiasis should undergo preoperative or intraoperative evaluation of the common bile duct (Figure 2).³¹

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 

  ibrahim_gallstones_t4.jpg
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.