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Gastric Bypass Surgery

The most commonly performed operation for morbid obesity in the United States is called gastric bypass. Other names for this procedure include Roux-en-Y gastric bypass or Roux-en-Y gastrojejunal bypass.

During Gastric Bypass Surgery

During surgery the stomach is divided into a small upper part and a large lower part. The small upper part of the stomach acts as the new stomach. This smaller part of the stomach is also called the stomach pouch or gastric pouch.

During gastric bypass surgery:

  • Six to eight tiny incisions are made to perform the operation
  • Surgeons insert long instruments through these tiny holes to perform the procedure
  • A camera is attached to one of these instruments, showing an image of the operation on a television monitor

A recent advancement is the use of robotic surgery to perform laparoscopic gastric bypass. The robot provides a high definition view and allows a more precise performance of complex laparoscopic procedures.

Both open and laparoscopic gastric bypass surgeries are performed at UPMC Hamot. Laparoscopic gastric bypass cannot be performed on every patient. During your consultation, you will be able to find out if you qualify for a laparoscopic gastric bypass surgery. The laparoscopic approach offers the advantages of smaller incisions and, typically, less pain and earlier recovery. There is also a lower incidence of ventral hernias (abdominal hernias) after laparoscopic gastric bypass compared with open gastric bypass.

Digestion After Gastric Bypass Surgery

  • About one-third of the small intestine is bypassed and 100 centimeters of intestine are connected from the small stomach pouch to the rest of the intestines.
  • The lower part of the stomach and its intestine will no longer be used.
  • Roughly two-thirds of the small intestine is still used for digestion and absorption of food after food passes from the small stomach pouch into the small intestine.
  • Since the stomach is smaller, a person feels full after a very small meal.
  • The connection between the gastric pouch and the small intestine is very small, and food tends to stay in the gastric pouch for a long duration, giving the person a feeling of fullness for several hours.
  • Since a part of the small intestine is bypassed, not all of the calories in food are absorbed.
  • This method helps with weight loss, but still requires a change in lifestyle.

What to Expect After Gastric Bypass Surgery

Gastric bypass can be regarded as a restrictive procedure. With gastric bypass, food skips the first section of the small intestines, where most iron and calcium are absorbed; therefore, risks for nutritional deficiencies are higher.

Gastric bypass may cause dumping syndrome, whereby stomach contents move too rapidly into the small intestine.

Symptoms of dumping syndrome, which usually pass in less than two hours, include:

  • Nausea
  • Weakness
  • Sweating
  • Faintness
  • Diarrhea after eating.

Many factors influence weight loss after gastric bypass surgery. Younger patients, men, and patients committed to making permanent lifestyle changes usually lose more weight. Individual weight loss results will vary, and 10 to 15 percent of patients may lose less than 50 percent of their excess weight.

Benefits and Risks of Gastric Bypass Surgery


  • Most patients lose weight rapidly and continue to do so until 18 to 24 months after the procedure.
  • Significant sustained weight loss. Although many patients regain some of their weight after 24 months, few regain all of their weight.
  • Bariatric surgery improves or eliminates most obesity-related conditions, such as high blood pressure, high cholesterol, sleep apnea, and diabetes.
  • Blood sugar levels for most patients with adult onset diabetes (Type II) improved almost immediately and become completely normal within a year of surgery.
  • Less pain associated with osteoarthritis and improved mobility.
  • Improved mood and self-esteem.


  • 10 to 20 percent of patients who have open bariatric surgery may require follow-up operations to correct hernias.
  • Other possible post-surgical complications include infection, bleeding, and death.
  • During rapid or substantial weight loss, a person’s risk of developing gallstones is increased. More than one-third of gastric bypass patients develop gallstones, which could lead to a laparoscopic procedure known as cholecystectomy to remove the gallbladder. Gallstones can be prevented with supplemental bile salts taken for the first six months after surgery.
  • Nearly 30 percent of patients who have bariatric surgery develop nutritional deficiencies, such as anemia, osteoporosis, and metabolic bone disease. These deficiencies can be avoided if lifelong vitamin and mineral intake are maintained.
  • Dumping syndrome caused by stomach contents moving too rapidly through the small intestine.

It is important to know that gastric bypass surgery cannot be completely reversed. The decision to have this procedure must be made in consultation with your surgeon, and after a very careful consideration of the potential benefits, risks, and lifelong consequences.

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Laparoscopic Surgery for Weight Loss
Dr. Amjad Ali discusses laparoscopic bariatric surgery.