BARIATRIC SURGERY
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.
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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.
