A guide for clinicians: Bariatric surgery and the ObGyn patient
A boom in surgical weight-loss procedures means you will be called on to manage women who have undergone—or are considering—one of these operations. Are you prepared?
IN THIS ARTICLE
CASE: New-onset abdominal pain and a history of bariatric surgery
A 28-year-old woman who is 14 weeks pregnant (G5P1A4) complains of abdominal pain, nausea, and vomiting for the past 3 days. Four years ago, she underwent a successful Roux-en-Y gastric bypass, and her body mass index (BMI) decreased from 61.1 to 34.8 as a result. Today, after unremarkable ultrasonography at an outside hospital, she is transferred to your facility, where she is noted to be afebrile and tachycardic (133 bpm) with a very tender abdomen and a white blood cell (WBC) count of 12.2×103/μL.
Could her symptoms be related to her history of gastric bypass? How should you manage her condition?
This case illustrates why it is imperative that Ob Gyns have a basic understanding of bariatric surgery—particularly the types of procedures being performed today and the complications that may arise.
In this case, urgent intervention is called for, given the elevated WBC count and extreme tenderness of the abdomen. This patient was taken to surgery without waiting for additional imaging studies. Operative findings included intussusception with necrosis, a late complication of the Roux-en-Y procedure, necessitating resection of 60 cm of small intestine ( FIGURE 1 ). Although fetal heart sounds remained encouraging overnight, fetal demise occurred the next day. The patient’s physical recovery was otherwise unremarkable.
This scenario is not as unlikely as you might imagine. A similar episode was described in 2004. 1 The outcome: maternal and fetal death.
FIGURE 1 Life-threatening intestinal obstruction
Patchy and continuous necrosis is evident following reduction of an obstruction-causing intussusception.
A boom in bariatric surgery
The incidence of surgical weight-loss procedures increased sixfold over a recent 7-year time span. 2 In 2008 alone, more than 200,000 people underwent this type of operation—at least half of them women of reproductive age. 2,3 In my experience at the University Hospitals of Cleveland Bariatric Program, which I directed, 85% of patients were women. 4 This percentage is similar to the gender breakdown in other bariatric programs.
Because you are called on to provide both primary and specialty care, you are very likely to encounter women who have undergone bariatric surgery or who are considering it. As the prevalence of morbid obesity continues to rise, so will the need for familiarity with surgical weight-loss reduction.
In this article, I offer an overview of bariatric surgery, focusing on:
- the different procedures performed today
- the potential complications associated with the most common operations
- the need for nutritional assessment.
In the process, I discuss the health benefits of bariatric surgery, including greater fertility and improved pregnancy outcomes.
How we talk about obesity
The language of obesity centers on a basic metric: the body mass index (BMI). 5 This index was devised in the 19th century by Adolphe Quetelet to describe total body fat.
Consider its use to describe two markedly overweight individuals. One stands 6 ft and weighs 500 lb; the other stands 5 ft and weighs 400 lb. It is obvious which person is heavier; the BMI quantifies who is actually bigger. The first individual has a BMI of 67.8, whereas the shorter person has a BMI of 78, despite weighing 100 lb less.
The formula for determining BMI is:
Among the imperfections of the BMI are its failure to differentiate between genders and its marked inaccuracy in persons who have significant muscle mass and limited body fat, such as body builders. However, it does make it possible to compare patients of different height and weight, thereby facilitating attempts to prognosticate the risk of illness and identify candidates for bariatric surgery ( TABLE 1 ).
The 1991 National Institutes of Health (NIH) Consensus Conference on Gastrointestinal Surgery for Severe Obesity recommended that bariatric surgery (restrictive and bypass procedures) be considered for patients who have a BMI of 40 or above and for patients who have a BMI of 35 or above with high-risk comorbidity. 6
How size is classified using the body mass index
Risk of illness and comorbidity
Obese (class I)
Obese (class II)
Morbid obesity (class III)
“Severe morbid obesity”
Most agree that bariatric surgery originated nearly 60 years ago with the jejunoileal bypass, a purely malabsorptive procedure in which the proximal jejunum was anastomosed to the distal ileum. 7-9 This operation was based on the observation of dramatic weight loss following major small-bowel resection. The procedure was thought to allow obese patients to eat with abandon, thanks to the limited absorptive ability of the small intestine’s mucosal surface, which would impede digestion. However, the operation was fraught with complications, including protein calorie malnutrition, bacterial overgrowth, and even death. In addition, despite the dramatic reduction in the absorptive surface of the small intestine, some patients eventually regained weight.
One may still encounter patients who underwent jejunoileal bypass many years ago. One particular complication of this procedure is worth mentioning: hepatic cirrhosis. Any patient who has a history of jejunoileal bypass should have her liver function assessed before undergoing procedures that require general anesthesia.
At present, bariatric surgery may incorporate a component of malabsorption, but no other procedures are purely malabsorptive ( TABLE 2 ).
Bariatric procedures for weight reduction, past and present
Mechanism of action
Vertical banded gastroplasty
Roux-en-Y gastric bypass
* No longer performed
Vertical banded gastroplasty (VBG). This procedure is one of the earliest successful restrictive procedures ( FIGURE 2 ). Although it was originally performed via laparotomy, it is easily carried out laparoscopically. However, a risk of complication, such as severe reflux, and a low long-term success rate have decreased its widespread application.
Laparoscopic adjustable silicone band. The most common restrictive procedure performed today is the laparoscopic adjustable silicone band (Lap-Band) ( FIGURE 2 ). Among its benefits are:
- easy insertion, especially in comparison with the gastric bypass
- ability to adjust the amount of restriction (not possible with VBG)
- elimination of the need for supplemental nutrition
Long-term results from a US population are not available because FDA approval did not occur until 2001. However, some centers outside the United States have reported unfavorable long-term outcomes. (See “Lap-Band complications may be pervasive,”.)
Laparoscopic sleeve gastrectomy (LSG). This operation was originally devised as the first stage of a duodenal switch. However, weight loss with this stage alone made LSG a bariatric procedure in its own right ( FIGURE 2 ).
Although this operation is categorized as restrictive, gastric sleeve resection eliminates the gastric fundus, the major site where ghrelin—“the hunger hormone”—is produced. This hormonal alteration may contribute to weight loss that occurs after LSG.
Magenstrasse and Mill operation. This operation converts the stomach into a long tube similar to the gastric sleeve. The greater curvature of the stomach is separated from the newly created tube but remains attached to the rest of the stomach at the antrum. (The greater curvature of the stomach is resected in the gastric sleeve procedure.)
Many insurers refuse to reimburse for restrictive operations other than the VBG and Lap-Band.
FIGURE 2 Three common surgeries
These restrictive procedures decrease the size of the stomach reservoir without impairing absorption of calories.
Biliopancreatic diversion, duodenal switch. Despite the risk of protein malnutrition, these two procedures attempt to produce selective malabsorption of fat and carbohydrate as a means of treating the most severely obese patients. These operations carry the highest mortality rate and are therefore less likely to be offered routinely.
Roux-en-Y gastric bypass (RYGB). In the United States, the RYGB is performed more frequently than other procedures that combine malabsorption and restriction. It is considered by most to be the “gold standard” bariatric operation ( FIGURE 3 ).
The RYGB may induce weight loss through one or more of the following mechanisms:
- a decrease in the size of the gastric pouch. After the procedure, this pouch has a capacity of about 30 cc (size of a thumb)
- the small diameter of the gastrojejunal anastomosis, which is usually 1 cm
- glucose intolerance. About 50% of patients experience dumping symptoms when they ingest refined carbohydrates
- subclinical malabsorption. Food does not encounter the majority of digestive enzymes until it reaches the jejunojejunostomy anastomosis
- suppression of ghrelin production. Ghrelin is a hormone produced primarily in the gastric fundus and secondarily in the duodenum, both of which are bypassed with the RYGB. Plasma ghrelin levels peak before meals and are suppressed with food intake. After RYGB, patients demonstrate a flattening of this pattern, which appears to correlate with a suppression of appetite. 10
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.
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.