Gastric Bypass Complications

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Like most other surgeries, gastric bypass surgery is associated with a degree of risk. The surgery is associated with various complications, some of which are more serious than others such as internal bleeding or blood clots.

Complications after surgery

Patients who undergo gastric bypass surgery are at risk of the following complications immediately after surgery:

  • Patients are at a 1% risk of death
  • The above risk is raised to 2.5% if the obesity is accompanied by high blood pressure
  • Similarly, the risk of death is 2.5% if the patient’s BMI is 50 or higher
  • The risk of infection is approximately 5%
  • The risk of deep vein thrombosis or pulmonary embolism is around 1%
  • Internal bleeding also occurs in around 1% of individuals who undergo this surgery

Longer term complications

The rapid weight loss that is achieved following a gastric bypass is in itself associated with a number of adverse effects and health risks. Some of these are described below:

Excess skin

The skin does not revert back to the firmness and shape it was prior to the patient becoming obese. Residual skin folds can be upsetting to live with from a cosmetic angle as well as from a hygiene perspective because the folds can develop rashes or become infected. Cosmetic surgery is sometimes considered to remove the excess skin.


Patients who have had bariatric surgery develop stones (usually made of cholesterol) in their gall bladder in about 8% of cases.

Stomal stenosis

This refers to when the channel that connects the stomach pouch to the small intestine becomes blocked by a piece of food. Stomal stenosis occurs in around 20% of those who have a gastric bypass and the most common symptom is vomiting. An endoscopy procedure can be performed to resolve the problem.

Further Reading

Last Updated: Jun 15, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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  1. Denise Mcconnell Denise Mcconnell United States says:

    many of these complications are also present in the person who loses weight by diet and exercise. excess skin, risk of blood clots, are also present in the obese patient. weight loss or not. gall stones happen more often in the obese person.  being obese raises the risk of any surgery, cancer, high blood pressure, diabetes, etc.. everyone dies. how you live it depends on you. the quality of life is improved for far more than those who choose to not do gastric bypass. conventional dieting does not work. if it did then the 180 BILLION dollar industry would be bankrupt... so post me something that is related only to bariatric surgery. so far this article does not do that.

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