Clinical Review

A guide for clinicians: Bariatric surgery and the ObGyn patient

OBG Manag. 2010 January;22(1):36-48

References

1. Moore KA, Ouyang DW, Whang EE. Maternal and fetal deaths after gastric bypass surgery for morbid obesity. N Engl J Med. 2004;351:721-722.

2. Bariatric Surgery in Women of Reproductive Age: Special Concerns for Pregnancy. Structured Abstract. Rockville, Md: Agency for Healthcare Research and Quality; November 2008. Available at: www.ahrq.gov/Clinic/tp/barireptp.htm. Accessed Dec. 8, 2009.

3. American Society for Metabolic and Bariatric Surgery. Metabolic and bariatric surgery fact sheet. Available at: www.asmbs.org/Newsite07/media/asmbs_fs_surgery.pdf. Accessed Dec. 8, 2009.

4. Stellato TA, Hallowell PT, Crouse C, Schuster M, Petrozzi MC. Two-day length of stay following open Roux-en-Y gastric bypass: is it feasible, safe and reasonable? Obes Surg. 2004;14:27-34.

5. Oria HE, Carrasquilla C, Cunningham P, et al. American Society for Bariatric Surgery Standards Committee, 2004–2005. Guidelines for weight calculations and follow-up in bariatric surgery. Surg Obes Relat Dis. 2005;1:67-68.

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10. Cummings DE, Weigle DS, Frayo RS, et al. Plasma ghrelin levels after diet-induced weight loss or gastric bypass surgery. N Engl J Med. 2002;346:1623-1630.

11. Hallowell PT, Stellato TA, Schuster M, et al. Potentially life-threatening sleep apnea is unrecognized without aggressive evaluation. Am J Surg. 2007;193:364-367.

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20. Lashen H, Fear K, Sturdee DW. Obesity is associated with increased risk of first trimester and recurrent miscarriage: matched case-control study. Hum Reprod. 2004;19:1644-1646.

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FIGURE 3 Roux-en-Y gastric bypass

A gastric pouch is created at the top of the stomach and connected directly to the jejunum, bypassing the rest of the stomach and duodenum.

When is bariatric surgery indicated?

The NIH Consensus Conference identified patients who might be candidates for bariatric surgery, as I noted:

patients who have a BMI of 40 or above, whether or not they have comorbidity
patients who have a BMI of 35 or above and comorbidity.⁶

These recommendations have been adopted by third-party payers.

Potential comorbidities include hypertension, coronary artery disease (CAD), lipid abnormality, diabetes, obstructive sleep apnea (OSA), and severe osteoarthritis, among others.

When identified together, several of these comorbidities constitute metabolic syndrome, a risk factor for CAD. More than 50 million Americans are thought to exhibit this syndrome, which is diagnosed when three or more of the following are present:

waist circumference ≥40 in (102 cm) in men; ≥35 in (88 cm) in women
triglycerides ≥150 mg/dL
high-density lipoprotein cholesterol <40 mg/dL in men; <50 mg/dL in women
blood pressure ≥130/85 mm Hg
fasting glucose ≥100 mg/dL.

Postsurgery weight loss has many benefits

Obstructive sleep apnea may resolve

Although this condition is known to be associated with obesity, it is drastically underdiagnosed.¹¹ In our program, only 21% of patients had been given a diagnosis of OSA at the time of initial evaluation for surgery. After we obtained a polysomnogram (sleep study) for each of them, however, the true prevalence was determined to be 91%.

OSA can have serious consequences if it is untreated, and it may increase the risks associated with surgery and general anesthesia. By identifying and treating OSA before gastric bypass (RYGB), we were able to eliminate the respiratory ICU stay—a benefit that should be applicable to nonbariatric surgeries in the morbidly obese patient as well.¹²

With successful bariatric surgery, OSA abnormalities identified during polysomnography are dramatically improved or eliminated. Treatment with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BIPAP) can usually be discontinued 6 months to 1 year after the dramatic weight loss associated with RYGB.

Cancer death rate may be reduced

Three consequences of morbid obesity not generally thought to be indications for bariatric surgery are:

obesity-associated cancer
decreased longevity
infertility.

However, each of these conditions may be improved through successful bariatric surgery.

In a prospective study of more than 900,000 adults in the United States who were followed for 16 years, overweight or obesity was thought to account for 14% of cancer deaths in men and 20% of cancer deaths in women.¹³ Death rates for persons who had a BMI of at least 40 were 52% higher in men and 62% higher in women than they were in people who had a BMI below that threshold. BMI was significantly associated with cancer of the esophagus, colon and rectum, liver, gallbladder, pancreas, and kidney, as well as with non-Hodgkin’s lymphoma and multiple myeloma.

A trend toward an increasing risk of death with higher BMI was observed for cancer of the stomach (men), prostate, breast (women), uterus, ovary, and cervix.

The benefits of bariatric surgery in regard to cancer incidence and longevity were revealed in a 15-year, nonrandomized, prospective study involving more than 4,000 patients.¹⁴ At 10.9 years of follow-up, with a follow-up rate of 99.9%, this investigation concluded that bariatric surgery reduces mortality attributable to cardiovascular disease and cancer.¹⁴ Most surprising was the finding of a reduced incidence of cancer in patients who underwent bariatric surgery, compared with matched controls.¹⁴ An editorial accompanying this study summed it up in the headline: “The missing link—lose weight, live longer.”¹⁵

The Framingham risk score estimates the 10-year risk of CAD. This score is reduced by more than 50% after successful gastric bypass surgery.¹⁶

After surgery, fertility improves and pregnancy has better outcomes

From your practice, you’re certainly aware of the detrimental effects that obesity has on fertility, pregnancy, and fetal health.^17-22 Although neither pregnancy nor impaired fertility is a primary indication for surgical weight reduction in an obese woman, bariatric surgery can improve the likelihood of fertility and successful pregnancy.

Advise patients to delay pregnancy after bariatric surgery. Although none of the bariatric operations performed today are contraindications to pregnancy, we caution all women to delay pregnancy—using two forms of birth control—until weight loss has stabilized. This usually takes about 12 to 18 months after surgery.

In our program, we identified 28 women who became pregnant following gastric bypass. Although we had cautioned all women to avoid early pregnancy, 10 became pregnant within 1 year of the bypass. Among these women, the rate of miscarriage was 40%, compared with 17% among the 18 women who waited more than 1 year to conceive. These percentages merit concern despite the small sample size.