Gastric bypass is the most frequently performed weight loss procedure in the United States of America.

Combined gastric bypass surgery is called “combined” because not only the size of the stomach but also the length of the gastrointestinal tract is reduced. A small pouch (15–30 ml in volume) is formed from the upper part of the stomach.

Gastric bypass is performed under general anesthesia, using minimally invasive laparoscopic approach.

The size of the stomach is reduced by almost 90 %*, therefore onetime food intake capacity decreases significantly, and the patient feels early sensation of fullness. Normally, food passes from the stomach into the small intestine which absorbs major proportion of nutrients as well as calories. The remaining food further passes into the large intestine. During the gastric bypass surgery, reduced stomach is connected directly to the middle part of the small intestine, thus bypassing the remaining gastric body and the upper part of the small intestine (duodenum). The procedure shortens the “path” of food through the gastrointestinal tract, and therefore less of it is absorbed. The extent of intestinal “bypass” is chosen according to patient’s BMI.

Possible complications specific to gastric bypass surgery

An anastomosis is a surgical connection between an intestine and the stomach or between two intestinal parts using special staples or sutures. Due to inappropriate healing of such connections, following complications are possible:

• Anastomotic leakage. This causes leakage of fluid from the gastrointestinal tract into the abdominal cavity and subsequent infection. Such complication occurs in 2 % cases, more often in the area of gastrointestinal anastomosis. Anastomotic leakage is usually treated with antibiotics. However, additional operation may be necessary.
• Anastomotic stricture. During the healing process of the anastomosis, scar tissue forms in that area. It normally recedes and only slightly narrows the diameter of the affected part of the gastrointestinal tract.  However, in some cases excessive scarring may narrow intestinal diameter significantly and even disturb passage of liquid materials. Such condition may be corrected during a gastro-endoscopic procedure in which the stricture is dilated using a special balloon.

• Ulceration of the anastomosis. Occurs in 1–16 % cases. Causes of ulceration include insufficient circulation of the anastomosis, tension, increased gastric acidity, use of non-steroid anti-inflammatory drugs. This condition is treated conservatively – medications, special diet are used.
• Gastric dumping syndrome. If lots of carbohydrates are ingested, they pass directly into the small intestine. Subsequently, the organism secretes large amounts of fluid into the intestine to dilute excessive sugars. The patient may therefore feel abnormal heart beating, cold sweating, strange sensations in the stomach and anxiety. Such state may last for up to 45 minutes and is often accompanied by diarrhea.
• Lack of particular nutrients, minerals and vitamins. To avoid such complications, well-balanced nutrition and food supplements are highly recommended postoperatively. Hyperparathyroidism may develop due to inadequate absorption of calcium.