Bariatric Surgery

Bariatric Surgery

1. Medical Versus Surgical Therapy
1. Medical Therapy
• has almost nonexistent long-term success


2. Surgical Therapy
• Swedish Obese Subjects (SOS) study published in 2007 was the first prospective controlled trial to document the efficacy of bariatric surgery over medical therapy in reducing diabetes, cardiovascular complications, cancer, and overall mortality in obese patients
• at 15 years, surgery patients had an 18% weight loss; medical patients had a 1% weight loss
• multiple other prospective, randomized trials have demonstrated the superiority of bariatric surgery over medical therapy for treating weight loss, diabetes, and other comorbidities


2. Mechanism of Action of Bariatric Surgery
1. Restrictive Procedures
• caloric intake is limited by reducing the stomach’s reservoir capacity
• laparoscopic sleeve gastrectomy (LSG) is the main restrictive procedure performed today, and has largely replaced the laparoscopic adjustable gastric band
• in restrictive procedures, stretch receptors in the proximal stomach mediate satiety via the vagus nerve
• LSG also causes hormonally-mediated satiety by removing the source of ghrelin (gastric fundus)


2. Malabsorptive Procedures
• decrease nutrient absorption by shortening the absorption length of the small intestine or by diversion of the biliopancreatic secretions that facilitate absorption
• jejunoileal bypass and biliopancreatic diversion are examples of purely malabsorptive procedures
• highly effective for weight loss, but they cause significant metabolic complications such as protein-calorie malnutrition and micronutrient deficiencies
• almost never performed today


3. Combination Procedures
• Roux-en-Y gastric bypass (RYGB) and duodenal switch with biliopancreatic diversion (BPD/DS) are both restrictive and malabsorptive
• RYGB also alters many gut hormone and neuropeptide levels (enteroencephalic endocrine axis)


3. Indications for Bariatric Surgery
• adults with a BMI ≥ 40 without a comorbid illness
• adults with a BMI between 35 and 40 with at least one serious comorbidity
• adults with a BMI between 30 and 35 with uncontrollable type 2 diabetes


1. Contraindications
• untreated major psychiatric disorders
• current drug or alcohol abuse
• untreated eating disorders (bulimia)
• prohibitive surgical or anesthetic risk
• inability to comply with life-long vitamin replacement


4. Preoperative Evaluation of Comorbid Conditions
1. Cardiovascular Evaluation
• need a functional assessment of activity in relation to cardiac function
• patients with a history of recent chest pain or change in exercise tolerance will need a formal cardiology assessment, including stress testing as necessary


2. Pulmonary Assessment
• history suggestive of sleep apnea will mandate a preoperative sleep study
• sleep apnea requires a CPAP or BIPAP mask postoperatively to reduce hypoxia
• asthma may require preop treatment
• hypoventilation syndrome of obesity (Pickwickian syndrome) should be suspected in patients with a BMI > 60. Arterial blood gases reveal a PaCO2 > PaO2 and an elevated hematocrit. These patients have a very high cardiopulmonary morbidity and mortality and require significant weight loss before surgery


3. Renal Assessment
• because of the high incidence of diabetes and hypertension, baseline renal function should be assessed by serum creatinine


4. Metabolic Conditions
• diabetes must be controlled preoperatively
• hyperlipidemia and hypercholesterolemia should be screened for


5. Cholelithiasis
• for restrictive operations, screening ultrasound is recommended
• if gallstones are present, cholecystectomy should be performed at the time of bariatric surgery


6. GERD
• very common in obese patients
• EGD is indicated in patients with GERD to detect Barrett’s esophagus and hiatal hernias


7. Nonalcoholic Steatotic Hepatosis (NASH)
• not a contraindication for bariatric surgery if there is no cirrhosis and portal hypertension
• bariatric surgery improves the prognosis of NASH
• large left liver lobe can make laparoscopic surgery difficult or impossible


8. Abdominal Wall Hernias
• repair is best postponed until after significant weight loss
• mesh placement at the time of bariatric surgery is problematic


5. Operative Procedures
1. Laparoscopic Adjustable Gastric Band (LAGB)
• FDA approved in 2002
• adjustable via fluid injection or removal into a subcutaneous port, allowing tightening or loosening of the band
• advantages include reversibility, lack of stapling, and ease of placement
• band requires 5 or 6 adjustments in the first year after surgery, and success requires patient compliance with return appointments, as well as a diet and exercise program
• relative contraindications include BMI > 50, large paraesophageal hernia, prior gastric resection or Nissen fundoplication
• anterior gastric wall is plicated over the band with several sutures to prevent herniation
• band should be secured 1 cm below the gastroesophageal junction and oriented along the 2- to 8-o’clock axis



1. Results
• randomized trials support LAGB over medical therapy for sustained weight loss, remission of diabetes, resolution of obesity-related comorbidities, and improvement of quality of life
• incidence of nutritional deficiencies is low because there is no disruption of the normal GI tract
• requires a highly motivated and compliant patient who will adhere to a strict diet and return to the office for port adjustments
• has largely been replaced by the gastric sleeve procedure


2. Complications
• has the lowest mortality rate of all bariatric procedures
• slippage of the band (4%) can cause acute or chronic esophageal obstruction
• erosion into the stomach is uncommon but requires reoperation
• port access problems are the most common complications







2. Roux-en-Y Gastric Bypass (RYGB)
• jejunum is divided ~ 40 cm from the ligament of Treitz
• Roux limb is 75 – 100 cm in most patients
• patients with BMI > 50 can have a Roux limb of 150 cm
• proximal gastric pouch is <30 mL in size
• Roux limb is typically oriented in an antecolic antegastric fashion to prevent internal hernias through the transverse mesocolon
• mesenteric defect in the jejunojejunostomy should also be closed
• gastrojejunostomy can be done with staplers or sutures
• a leak test should be done at the completion of the gastrojejunostomy
• if clinically indicated, a Gastrografin swallow can be done postoperatively to evaluate for leak or obstruction



1. Results
• procedure with the longest track record
• multiple studies document durable weight loss and remission of metabolic disease
• very effective at resolving heartburn symptoms


2. Complications
• mortality rate is < 1%, and is usually related to pulmonary embolism or sepsis from an anastomotic leak


1. Anastomotic Leak
• usually from the gastrojejunostomy
• persistent tachycardia is often the only sign and should prompt a CT scan with oral contrast
• most leaks are managed with drains, NPO


2. Internal Hernias
• require prompt reoperation because of the risk of strangulation
• CT scan is the best diagnostic tool
• retrograde distention of the biliopancreatic limb can lead to disruption of the gastric staple line
• Petersen defect is the space between the mesentery of the roux limb and the transverse mesocolon (#1 in the image below)
• additional mesenteric defects include the jejunojejunostomy mesenteric defect (#2) and the transverse mesocolon defect (#3)
• all 3 of these defects should be closed at the time of surgery
• placing the roux limb in the antecolic position eliminates the transverse mesocolon defect



3. Gastrojejunostomy Stenosis
• manifested as progressive intolerance to solids then liquids, beginning at 4 – 6 weeks postop
• usually successfully treated with endoscopic balloon dilation
• seems to be most associated with the circular stapler


4. Metabolic Complications
• iron deficiency anemia is common since RYGB bypasses the sites of maximum iron absorption (duodenum, proximal jejunum)
• vitamin B₁₂ deficiency is due to inefficient absorption because of delayed mixing with intrinsic factor
• calcium deficiency and protein malnutrition are also long-term complications that require rigorous monitoring of nutritional status
• vitamin B₁ deficiency can occur after prolonged vomiting after surgery and can present with confusion and extremity paresthesias


3. Laparoscopic Sleeve Gastrectomy
• most recently introduced bariatric procedure (2010)
• by 2012, incidence of the procedure had increased from 0.9% to 36.3% of all bariatric procedures performed in the U.S.
• advantages of the procedure include: technical ease (no anastomoses), preservation of the pylorus, reduction of ghrelin levels, reduction in internal hernias, no need for serial adjustments of a gastric band, reduction of malabsorption, and ability to convert to a RYGB or duodenal switch at a second stage if necessary
• procedure removes the lateral aspect of the stomach from the antrum to the angle of His
• a sleeve is created around a 32 – 40 French bougie
• must preserve the left gastric vessels
• most surgeons reinforce the staple line to prevent bleeding or leaks
• one side effect of a gastric sleeve is that it makes the stomach a high-pressure organ with a sphincter at both ends – this makes it more prone to leaks than the RYGB



1. Results
• excess weight loss results are equivalent to RYGB at 3 years; however, over time the sleeve can expand and lose its restriction, resulting in weight gain and recurrence of diabetes
• associated with fewer overall complications than RYGB


2. Complications
1. Leaks
• associated with a higher leak rate than RYGB
• early leaks are associated with technical issues (stapler misfires or traumatic tissue handling)
• late leaks are associated with tissue ischemia or high intragastric pressures
• best diagnosed by CT scan with oral contrast
• management includes adequate drainage, NPO, TPN, antibiotics, and endoscopic stenting to prevent ongoing contamination



2. GERD
• high intragastric pressures can result in disabling reflux, which may require conversion of the sleeve to a RYGB


4. Duodenal Switch with Biliopancreatic Diversion
• weight loss is primarily based on malabsorption, but there is a restrictive component as well
• least common bariatric procedure performed because of its technical complexity and potential for severe malabsorptive nutritional deficiencies
• common channel is 100 cm
• entire alimentary tract is 250 cm, with the ileum anastomosed to the duodenum
• in patients with very high BMIs, the procedure may be done in 2 stages: sleeve gastrectomy is performed first, and after sufficient weight loss, the second stage is technically easier



1. Results
• excess weight loss is the highest of the common bariatric procedures
• highly effective in treating comorbid conditions such as hypertension, diabetes, lipid disorders, sleep apnea
• patients have 2 – 4 foul-smelling bowel movements/day
• patients must take daily calcium supplements, as well as monthly fat-soluble vitamins


2. Complications
• has the highest mortality rate
• protein malnutrition is significant and occurs in up to 12% of patients
• some patients require reoperation to increase the common channel or reverse the procedure entirely
• malabsorption of iron and calcium, as well as fat-soluble vitamins, must be monitored carefully