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Risks of Gastric Bypass

While gastric bypass offers exceptional benefits, it also comes with its share of potential risks. The procedure itself is more complex than other bariatric procedures such as the gastric sleeve and can therefore produce additional complications and considerations. However, surgical risk can be minimized by employing an experienced surgeon with demonstrated exceptional surgical outcomes.  It is also very important to follow all preoperative recommendations provided by your surgical team.

The following is not intended to be a comprehensive guide to the potential risks of gastric bypass surgery, as every patient will have a different risk profile. However, the more you know about the risks of surgery the more able you will be to make an informed decision and to avoid them. Speak to your surgeon and find out what you can do to minimize risks.

General Surgical Risks

Any surgical procedure carries some degree of risk. Obese patients, who may be in poorer health, often have a heightened risk for infection and other post-operative complications. Further, obesity-related diseases such as type-2 diabetes may complicate recovery. Other potential surgical risks may include incisional hernias (less common with laparoscopy), swelling in the gastrointestinal system, ulcers, bleeding, stroke, heart attack, deep vein thrombosis or blood clots to the legs, pulmonary embolus or blood clot to the lungs and rarely, death.

To learn more about the risks of any surgery please speak to your surgeon. They will also be able to explain risks unique to your particular health circumstances.

Gastric Bypass Risks and Considerations

  • Dumping syndrome, a very uncomfortable but generally not life-threatening condition, may occur as a result of eating high-fat or high-sugar foods after surgery. Patients who drink liquids with meals may make dumping syndrome worse. Symptoms of dumping include vomiting, dizziness, sweating, fainting, and diarrhea.
  • The staple line used to seal the new gastric pouch may leak, necessitating a surgical procedure to fix the problem. If a leak does occur there is a high risk of a serious infection.
  • The stomach pouch may stretch over time, causing weight gain. This can be corrected with various minimally invasive follow-up procedures.
  • Ulcers, gastric reflux, and bloating or gas may occur.
  • Parts of the gastrointestinal system may not be easily seen in X-rays after surgery and may obscure ulcers, tumors, or internal bleeding.
  • Patients will need to take nutritional supplements for the rest of their lives as the combination of restriction and malabsorption rarely allows a gastric bypass patient to consume enough nutrients through food alone. Nutritional deficiencies can potentially occur without adequate daily supplementation. Patients will also need to supplement their diet with protein.
  • Hair loss or thinning may occur. This is generally temporary and secondary to decreased nutritional intake after surgery.
  • Gastric bypass patients will need to change their lifestyle through a new diet and exercise program in order to be successful after surgery.

While there seem to be potential risks of surgery, complication rates are historically low, particularly when performed at Centers of Excellence. A 2004 ASMBS consensus statement estimates the complication rates of gastric bypass at about 5% and mortality at .5% when surgery is performed by a skilled bariatric surgeon.1

Ways to Minimize Risk

  • Choose a surgeon experienced in your procedure and with exceptional surgical outcomes.
  • Stop smoking before surgery.
  • Try to lose some weight before surgery.
  • Tell your surgeon about all medical problems you may have experienced or are currently experiencing.


  1. Buchwald H. 2004 ASBS consensus conference statement, bariatric surgery for morbid obesity: health implications for patients, health professionals, and third party payers. Surg Obes Related Dis. 2005;1:371-378.

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