EVIDENCE-BASED ANSWER
The risk of bowel strangulation is estimated to be small—less than 1% per year (strength of recommendation [SOR]: B, based on small cohort studies with short follow-up). Experts recommend repair for patients with risk factors for poor outcomes after potential strangulation. These risk factors include advanced age, limited access to emergency care, significant concomitant illness, inability to recognize symptoms of bowel incarceration, and poor operative risk (American society of Anesthesiologists class III and IV) (SOR: C, based on expert opinion and case series). It is reasonable to offer elective surgery or watchful waiting to low-risk patients who understand the risks of strangulation (SOR: C, based on expert opinion and case series).
Clinical commentary
Watchful waiting, yes, but not for high-risk seniors
Michael K. Park, MD
University of Colorado Health Sciences Center, Rose Family Medicine Residency, Denver
The evidence reinforces “watchful waiting” as a reasonable management approach. However, certain patients—say, a 66-year-old diabetic farmer—should probably undergo elective herniorrhaphy to preempt the increased risk of complications with emergent repair.
shared decision-making is an essential process in accounting for individual preferences. In addition to knowing the risks of strangulation, patients opting for surgery also need to be aware of the differences between open and laparoscopic techniques. The former may be done under local anesthesia; the latter decreases postoperative pain and recovery time, but requires general anesthesia and increases the rates of serious complications.
Evidence summary
In 2 randomized controlled trials (RCTs) comparing elective repair of inguinal hernias with watchful waiting, the cohorts who made up the control groups experienced strangulation rates of 1.8 per thousand (0.18%) and 7.9 per thousand (0.79%) occurrences per patient-year.1,2 In the first of these 2 trials,1 with 364 control group patients, median follow-up was only 3.2 years (maximum 4.5 years), and by 4 years 31% of patients had crossed over to the treatment group for elective repair. The mean follow-up time in the second trial,2 which had 80 control group participants, was 1.6 years; 29% of patients eventually crossed over for repair.
Spanish study may have overestimated the risk. A retrospective study3 of 70 patients with incarcerated inguinal hernias presenting for emergency surgery in Northern Spain reported a cumulative 2.8% probability of strangulation at 3 months, rising to 4.5% after 2 years. This study did not include patients presenting for elective repair of hernias, and therefore it likely overestimated the rate of strangulation among patients in a primary care setting.
When to repair inguinal hernia
Experts recommend repair of an inguinal hernia in patients with risk factors for poor outcomes after potential strangulation. Risk factors include advanced age and significant concomitant illness.
In 2001, a prospective study4 of 669 patients presenting for elective hernia repair in London found that only 0.3% of patients required resection of bowel or omentum.
Risk appears to be <1% a year. Collectively, these studies suggest that the risk of strangulation is less than 1% per year (0.18% to 0.79%) among all patients with inguinal hernias, at least in the first few years of the onset of the hernia. As you’d expect, the risk of strangulation is higher (2.8% to 4.5%) among patients presenting for emergency repair of incarcerated hernias. We found no prospective studies that followed patients for more than 4.5 years.
Age factors into poor outcomes
A number of studies5,6 have examined risk factors for increased rates of strangulation and poor outcomes. Older age increases the risk of a poor outcome, peaking in the seventh decade. Patient comorbidity and late hospitalization also make emergent repair more risky.3,5