Complications of Gastric Bypass Surgery

Complications of gastric bypass surgery vary according your procedure and other influential factors before and after surgery. This page reviews the most common complications and how to reduce your risk.


Open vs Laparoscopic Gastric Bypass Complications

Certain complications, including anastomotic leaks, pulmonary embolism and pneumonia, have the same chance of occurring after both open and laparoscopic surgery. But the risk of other complications changes depending on which procedure you have.

A study that compiled the results from over 6,200 gastric bypass surgery patients found that open gastric bypass surgery carries a higher risk of:1

The same study also found that laparoscopic gastric bypass patients have a higher incidence of:

It is thought that the laparoscopy-related complications are the result of the bariatric surgeon’s level of experience, while the higher rate of open surgery complications results from the larger incisions.

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Likelihood of Developing Complications of Gastric Bypass Surgery

Following are the mortality and complication rates from two separate studies that showed early complications of gastric bypass surgery to occur in 10% of patients and late complications to occur in up to 15.3% of patients:

Study # of gastric bypass
patients in study
Complication Rate Year
References: A, B
Study A 111 Early complications – 10%
Late complications – 15.3%
Study B 70 Early complications – 10%
Late complications – 8.1%
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Potential Complications of Gastric Bypass Surgery

The following list of gastric bypass complications may appear intimidating, but keep in mind that complication rates vary widely depending on the experience of your surgeon and your behavior before and after surgery.

Further down the page we’ll direct you to resources that will help you find, interview and choose the right bariatric doctors and help you understand how to minimize your risks.

First, let’s review the list of potential complications (click the links below for more information including definitions and treatments, then click the 'Back' button in your browser to come back to this page)…

For a complete list and comparison of complications relating to all types of bariatric surgery, see our Bariatric Surgery Complications page.

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Complications of Gastric Bypass Surgery -
How to Minimize Your Risk

We have several pages that will help you determine the best way to reduce your risk during and after gastric bypass surgery. Follow one of the below links depending on where you are in the process:

  • Your first step is to make sure that you select the surgery that is most appropriate for your situation. Different surgeries carry different risks for different people. Our Types of Bariatric Surgery page compares and contrasts the safest and most effective procedures.
  • If you haven't done so already, next review our Bariatric Surgery Complications page. In addition to providing a full list of definitions and treatments, it also illustrates which complications apply to each type of surgery, factors that increase your risks and 10 ways to minimize your risk of complications.
  • As mentioned above, your surgeon can have a lot to do with your outcome. For example, one study evaluated a surgeon over his first 300 laparoscopic gastric bypass patients.2 Following were his results as he gained experience:
Group Time in surgery Number of reoperations Number of conversions to open surgery
First 100 patients 163 minutes 9 2
Second 100 patients 119 minutes 2 1
Third 100 patients 94 minutes 1 1

Obviously, being in the 3rd group is the most desirable.

A separate and much larger study of over 15,000 patients in Michigan had similar findings about surgeon experience:3

# of procedures performed by surgeon over 3 years Rate of serious complications occuring within 30 days of surgery
Less than 100 cases 3.8%
100 - 249 cases 2.4%
Greater than or equal to 250 cases 1.9%

Most surgeons offer free seminars that teach you about your weight loss surgery options and their offices experience, total procedures performed and specific results. The seminars also allow you to get to know the surgeon prior to a one-on-one consultation (usually free as well).

Click here to find and schedule a free in-person seminar or one-on-one consultation with a qualified weight loss surgeon in your area.

You can also review our Bariatric Doctors page to learn how to interview multiple doctors and choose the best one.

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  1. Podnos YD, Jimenez JC, Wilson SE, Stevens CM, Nguyen NT. Complications after laparoscopic gastric bypass: a review of 3464 cases. Arch Surg. 2003 Sep;138(9):957-61.
  2. Pournaras DJ, et al.  Three Hundred Laparoscopic Roux-en-Y Gastric Bypasses: Managing the Learning Curve in Higher Risk Patients. Obesity Surgery. DOI 10.1007/s11695-009-9914-7
  3. Birkmeyer NJ, et al. Hospital complication rates with bariatric surgery in Michigan. JAMA. 2010 Jul 28;304(4):435-42.

[Last editorial review/modification of this page: 11/8/2011]

Disclaimer: The information contained in this web site is provided for general informational purposes only. It is not intended as nor should be relied upon as medical advice. Rather, it is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician(s). Before you use any of the information provided in the site, you should seek the advice of a qualified medical, dietary, fitness or other appropriate professional. Read More