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Although Laparoscopic Gastric Bypass is relatively safe it is a major operation and
there are important and potentially lethal complications known to be associated with this operation.
For More Information See: Risks of Operation

Short Term Complications (in the first 3 to 14 days)

The most common serious early complications are:

Other reported complications include:

Narrowing or ulceration of the connection between the stomach and the small bowel has been reported in one series in about 20% of all patients undergoing gastric bypass.

Bile Reflux Gastritis occurs when bile flows back into the stomach.  We have seen symptoms of Bile Reflux Gastritis in 6% of our patients.  In every case the patient's symptoms resolved after treatment with antacids and Actigall.

Fistulas, (an abnormal passage leading from one hollow organ to another) abscess and infection have been seen in gastric bypass operations.

Dumping Syndrome (Symptoms of the dumping syndrome include vasomotor and cardiovascular problems with weakness, sweating, nausea, diarrhea and dizziness) occurs in some patients with bypass.

Gallstones have developed in 3 of our 95 patients requiring postoperative laparoscopic cholecystectomy.  To decrease this already low rate of gallstones we have begun using Actigall.

Adhesions, scar tissue caused by healing after surgery, are much less common after laparoscopy.

Caffeine Withdrawal Headache has been to shown to occur in many patients who drink coffee, tea or sodas.  This can happen after surgery and can be a very painful experience.  Avoid this problem and stop all caffeine intake well before the surgery.


Arthritis, has been reported following the old jejuno-ileal bypass and the duodenal switch / biliopancreatic diversion operation.  It has not been seen in any Mini-Gastric Bypass patients to date.

Long Term Complications

Vitamin and Mineral Deficiencies

Decreases in iron, vitamin B12, and/or Folate levels were detected eight months to eight years (median, two years) after the operation. Oral Multi-Vitamins are useful in preventing Folate and B-12 deficiency after gastric bypass.

Peripheral neuropathy (disorders resulting from injury to the peripheral nerves) has been reported after operation.

Osteoporosis and Bone Loss.

Gastric bypass procedures carry the highest risk of multiple micronutrient deficiencies, that may supervene despite close medical follow-up.

Patients with a gastric bypass have a greater frequency of microcytosis and anemia, more frequent subnormal serum levels of vitamin B12, and impressive failure to absorb food vitamin B12. 

Gastrointestinal bleeding from a duodenal ulcer four years after having a gastric bypass procedure for obesity

Symptomatic gallstones requiring cholecystectomy

Abdominal Wall Hernia


Many studies show that pregnant obese patients and their babies are at increased risk.   Studies also document potential complications of pregnancy after gastric bypass operation.