Preoperative Gastrointestinal Assessment Before Bariatric Surgery

Obesity is a major health problem throughout the world. Bariatric surgery is frequently considered among the treatment options for the severely overweight, and surgically induced weight loss has become the best treatment for many morbidly obese people. A preoperative assessment to evaluate the suitability of a patient for a given operation and to clarify factors that may affect the outcome of a planned procedure should be carried out before the surgery. Preoperative evaluation of the gastrointestinal tract by a gastroenterologist before bariatric surgery yields important information that can lead to changes in planned treatments. This article discusses the factors that a gastroenterologist should assess before the surgery.

Obesity is a major health problem throughout the world, and nearly one-third of the population of the United States is considered obese. Obesity surgery is frequently considered among the treatment options for the severely overweight, and surgically induced weight loss has become the best treatment for many morbidly obese people. Before bariatric surgery, an extensive preoperative assessment is warranted to evaluate whether a patient is appropriate for a given operation and to clarify factors that may affect the outcome of a planned procedure. Gastroenterologists often are called in for the preoperative gastrointestinal (GI) assessment of a patient who is being considered for bariatric surgery. This article explores some of the relevant issues for gastroenterologists to consider when consulting on these patients.

Preoperative evaluation

Patients who are candidates for bariatric surgery are evaluated in the same fashion, regardless of the type of bariatric procedure that is being considered. Evaluation typically includes a thorough assessment of the indications for surgically induced weight loss, identification of factors that may mitigate the success of a procedure, and a search for comorbid disease. Typical assessments include psychological testing, nutrition evaluation, and medical assessment.

Nutritional Assessment

The gastroenterologist is a part of the multidisciplinary team, and so an understanding of the nutritional assessment of the patients who are preparing for bariatric surgery is important. In general, a nutritionist will provide a complete nutritional assessment and will coordinate preoperative weight loss attempts. Patients who lose at least 10% of their excess body weight preoperatively have more rapid loss of weight and shorter hospital stays after surgery. The use of a very-low-calorie diet for 6 weeks before planned surgery is associated with an improved access to the stomach during laparoscopic surgery and a reduction in liver volume by 20%.

Medical Assessment

The general medical assessment of a patient who is being considered for bariatric surgery is similar to that for any other major abdominal surgery ( Box 1 ). Patients are usually evaluated with laboratory testing that may include complete blood counts, metabolic profile, coagulation profile, ferritin level, thyroid function testing, and a lipid profile. For those in whom a malabsorptive procedure is being contemplated, vitamin B ₁₂and fat-soluble vitamin levels may be considered. Pulmonary assessment often includes a chest radiograph, arterial blood gas measurement, and tests of pulmonary function. Cardiac assessment includes an electrocardiogram and may also include a stress test to identify unsuspected coronary artery disease. Sleep apnea is an important consideration in many obese patients, and so a sleep study may be part of the evaluation.

Box 1

Preoperative blood testing
- Complete blood count
- Metabolic profile
- Coagulation profile
- Ferritin
- Thyroid function test
- Lipid profile
- Vitamin B ₁₂
- Fat-soluble vitamin levels
Cardiac
- Electrocardiogram
- Consider exercise stress test
Pulmonary
- Chest radiograph
- Arterial blood gas
- Pulmonary function testing
Sleep study
GI evaluation
- Upper GI series
- Upper endoscopy
- Abdominal ultrasonography
- Helicobacter pylori testing

Typical preoperative studies in patients undergoing bariatric surgery

GI Assessment

A thorough assessment of the GI tract before bariatric surgery is important to ensure successful outcomes. This assessment may include endoscopy, testing for Helicobacter pylori , and evaluation of the liver and gall bladder.

Upper endoscopy

The role of upper endoscopy in the preoperative evaluation of patients who are being considered for bariatric surgery is to detect upper GI abnormalities, even in asymptomatic patients. Many patients with symptoms of dyspepsia, dysphagia, and reflux are evaluated with endoscopy, and the situation of an obese patient with these complaints is no different. Many studies have demonstrated that routine preoperative endoscopy in the bariatric patient detects various abnormalities that need specific approaches before surgery and that such preoperative endoscopy is warranted. It is important to remember that some operations done for obesity, for example, Roux-en-Y gastrojejunal bypass (RYGB) and sleeve gastrectomy with duodenal switch and biliopancreatic diversion, make the distal stomach and duodenum inaccessible after the surgery. It would be reasonable to perform a preoperative examination of the upper GI tract is this setting.

Endoscopy is useful in the preoperative assessment of the bariatric patient to find or treat lesions that might lead to alterations in the type of surgery that has been planned, that might cause complications in the patient postoperatively, or that might lead to symptoms after surgery. In one study, esophagogastroduodenoscopy before bariatric surgery identified abnormalities in nearly 90% of patients, with 62% having clinically important findings. The most common lesions identified were hiatal hernia (40%), gastritis (29%), esophagitis (9%), gastric ulcer (4%), Barrett esophagus (3%), and esophageal ulcers (3%). Another study of 626 patients detected abnormalities in 46% of the patients, including gastritis (21%), esophagitis (16%), hiatal hernia (11%), and duodenitis (8%). One case of gastric cancer was detected. Another case report describes an early gastric cancer detected in the preoperative assessment for bariatric surgery. Many other studies have demonstrated that routine endoscopy before laparoscopic adjustable gastric band, vertical banded gastroplasty, and Roux-en-Y procedures can identify many abnormalities. A recent meta-analysis demonstrated that obesity is associated with a significantly increased risk of gastroesophageal reflux disease, erosive esophagitis, and esophageal adenocarcinoma, making endoscopic evaluation warranted to detect such abnormalities preoperatively. Two studies have demonstrated that findings of endoscopy led to a delay in surgery or a change in the surgical approach. European Society guidelines recommend upper endoscopy in all patients as a part of the preassessment before bariatric surgery, whether or not the patient has symptoms. Contrast studies, such as an upper GI series, may provide additional information to an endoscopy or may be an alternative; in one study of morbidly obese patients, radiographs were found to be superior to endoscopy in diagnosing sliding hiatal hernias before gastric bypass.

Concern about the safety of sedation for endoscopy in the severely obese patient has led to investigation. In general, endoscopy is safe and effective in this population, although an increased risk of hypoxemia has been demonstrated in those with a body mass index greater than 28, and obesity may make rescue from complications of oversedation, such as mask ventilation, more difficult. Madan and colleagues found that monitored anesthesia care with propofol was equivalent to endoscopist-administered sedation with benzodiazepines and narcotics in a randomized trial of 100 morbidly obese patients who underwent upper endoscopy before bariatric surgery, although there was a trend toward some better outcomes with monitored anesthesia care.

An American Society for Gastrointestinal Endoscopy (ASGE) guideline, on the role of endoscopy in the bariatric surgery patient, published in 2008, has the following recommendations :

1.

An upper endoscopy should be performed in all patients with upper-GI tract symptoms who are to undergo bariatric surgery
2.

Upper endoscopy should be considered in all patients who are to undergo an RYGB, regardless of the presence of symptoms
3.

In patients without symptoms and who were undergoing gastric banding, a preoperative upper endoscopy should be considered to exclude large hernias that may change the surgical approach.

Evaluation and treatment of H pylori

Preoperative testing for H pylori has been advocated in patients having bariatric surgery. H pylori infection rates in this group are comparable to those seen in the general population, with H pylori reported to be present in 30% to 40% of the patients being considered for bariatric surgery. Noninvasive urease testing that was positive for H pylori was associated with the patient having an abnormal endoscopy more frequently than H pylori negative noninvasive urease testing (94% vs 51%). Schirmer and colleagues reported that patients tested for H pylori had a lower incidence of postoperative marginal ulcers (2.4%) than did patients who did not undergo such screening (6.8%). If H pylori infection is detected, preoperative therapy for eradication is advised. The ASGE guidelines also state that patients without symptoms and who are not undergoing an endoscopy, if found positive for noninvasive H pylori , should be recommended for treatment.

Liver and gall bladder

Liver histology in obese patients typically reveals significant abnormalities, including nonalcoholic fatty liver disease. Gastric bypass for obesity is associated with a dramatic improvement or normalization of liver histology in most patients. Therefore, liver disease should be assessed by the gastroenterologist preoperatively, usually with a combination of blood testing and imaging studies, such as ultrasonography. If cirrhosis is suspected, liver biopsy may be confirmatory. In one study, 73% of patients with confirmed histologic abnormalities of the liver before bariatric surgery had the changes normalize, and another 13% of patients had their abnormalities improve.

Obesity is also associated with an increased prevalence of gallstones. Preoperative ultrasonography, as part of the evaluation of the GI tract before bariatric surgery, allows for detection of gallstones. If stones are present, the surgeon may consider a cholecystectomy at the same time as the bariatric procedure.

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