Obesity is associated with a decrease in the quality of life as well as the life expectancy. Although both medical therapy and caloric reduction remain the first-line therapies for obesity, bariatric surgery is the most effective therapy for sustained weight loss. Bariatric surgery is considered for people with a body mass index greater than 40 kg/m2, or for those with a body mass index less than 40 kg/m2 and obesity-related diseases. Bariatric surgery involves surgical manipulation of the gastrointestinal tract to alter normal anatomy and physiology to accomplish weight loss. Weight loss has been described through two mechanisms: restriction of food intake and malabsorption of ingested food. Additionally, the neurohormonal effects of bariatric surgery are now recognized as an important mechanism for both weight loss and improvement in comorbid conditions. Along with weight loss, bariatric surgery can improve comorbidities, including diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea, and GERD. Relative contraindications include poorly managed psychiatric disease, a history of eating disorders, poor compliance with dietary modifications, or high concern about the patient’s ability to comply with medical follow-up.
The most common bariatric surgeries currently performed are (1) laparoscopic adjustable gastric banding (LAGB), (2) sleeve gastrectomy, (3) Roux-en-Y gastric bypass (RYGB), and (4) biliopancreatic diversion with duodenal switch (BPD/DS). Operations are typically performed laparoscopically, unless intraoperative complications or technical difficulties require conversion to an open procedure.
LAGB involves placing an inflatable band along the proximal stomach, approximately 20 to 30 cm from the gastroesophageal junction at the angle of His. The anterior surface of the stomach is sewn over the band to secure it in place. Tubing with an attached port is connected to the band and placed in the anterior abdominal wall to control inflation. Postoperatively, the band is adjusted based on weight loss. Although this technique is effective, the amount of weight loss that results is less than with the other three types of bariatric surgeries. Complications can include band slippage, band erosion, prolapse of the distal stomach into the band, or malfunction of tubing. The popularity of this procedure has decreased because sleeve gastrectomy produces more weight loss.
Sleeve gastrectomy has rapidly become the most popular surgery for obesity. It involves a gastrectomy from the antrum to the angle of His, using a stapled division of the stomach. A bougie or endoscope is used during the operation to ensure that the gastric sleeve is of adequate diameter. The explosive increase in frequency of sleeve gastrectomies is due to the increased weight loss produced compared with LAGB, the technical ease of the surgery, and the decreased risk of nutritional deficiencies compared with RYGB. Complications include a postoperative leak along the proximal staple lines and continued GERD. Patients with preexisting GERD are often referred for RYGB over sleeve gastrectomy.
RYGB remains a popular procedure despite a transition in the field of bariatric surgery from open to laparoscopic or robotic procedures. For the procedure, the jejunum is divided approximately 50 cm from the ligament of Treitz. The section of jejunum in continuity with the stomach is now the biliopancreatic limb. The other half of the small bowel forms the Roux limb. An anastomosis is created between the biliopancreatic limb and the Roux limb. A small gastric pouch is created in the proximal stomach. The Roux limb is anastomosed to this gastric pouch, completing the procedure. Complications include anastomotic leak or stenosis, marginal ulcers, and nutritional deficiencies due to mal- absorption. RYGB is second only to the BPD/DS in efficacy for weight loss.
BPD/DS is the most effective procedure for weight loss and is therefore considered for morbidly obese patients. First, the greater curvature of the stomach is resected, as in a sleeve gastrectomy. The ileum is divided approximately 250 cm from the ileocecal valve.
The duodenum is divided, and the distal ileal segment is anastomosed to the duodenal segment attached to the stomach. The other limb, which carries pancreatic enzymes, is anastomosed to the terminal ileum. Although it has been highly effective for weight loss, BPD/DS is performed in only a minority of people undergoing bariatric surgery because of its technical difficulty and complication rate and the associated extreme malabsorption and large stool output.
The short-term complications are wound infection and surgical leak, bleeding, deep venous thrombosis, and pulmonary embolism. The late complications include cholelithiasis, short bowel syndrome, stomal stenosis, marginal ulcers, nutritional deficiencies, and dumping syndrome. The importance of dietary instructions and follow-up cannot be overemphasized.