Gastric Bypass Surgery Deaths: 3 Most Common Causes & Other Risks of Gastric Bypass

As with any major operation, gastric bypass surgery deaths are one of the unlikely but possible risks of gastric bypass. Fortunately, there are several things you can do minimize the already low chances…

Comparing gastric bypass surgery deaths to deaths caused by other bariatric procedures

Taking the weighted average of the following 7 studies shows the gastric bypass surgery mortality rate to be 0.24%…

Study # of gastric bypass
patients in study
Mortality Rate Year
Gastric bypass surgery deaths - References for this chart: A, B, C, D, E, F, G
Study A 1,364 0.15% 2008
Study B 111 0.9% 2007
Study C 494 0.6% 2006
Study D 70 0% 2006
Study E 25,759 0.25% 2006
Study F 925 0% 2004
Study G 5,644

The 0.24% mortality rate can be further broken down into open vs laparoscopic surgery:1

Open Surgery Mortality Rate Laparoscopic Surgery Mortality Rate
Note: The overall 0.24% mortality rate is closer to the 0.2% laparoscopic rate because this type of surgery is more common
2.1% 0.2%

While open surgery is a bit more dangerous as a procedure, the difference between these two rates may be due to the fact that many patients undergoing open surgery are heavier and sicker than those receiving laparoscopic surgery. 

So how do gastric bypass deaths relate to other procedures?

In general, lap band surgery is less risky while more complicated procedures like the duodenal switch carry more risk.

Following is the weighted average mortality rate of other procedures from studies referenced throughout our site…

Bariatric Surgery Procedure # of studies included Total # of patients from combined studies Weighted Average Mortality Rate
* Need more long term studies to confirm their effectiveness.
** Gastric bypass surgery deaths may be higher after duodenal switch surgery because tends to be a better procedure for patients at higher risk (i.e. higher BMI).
Mini Gastric Bypass Surgery* 4 744 0.13%
Gastric Banding (Lap band surgery) 4 1,945 0.16%
Vertical Banded Gastroplasty 4 993 0.2%
Gastric Bypass Surgery** 6 28,763 0.24%
Gastric Sleeve Surgery 4 732 0.27%
Duodenal Switch 4 3,433 1.0%**
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Bariatric Surgery Mortality vs. Mortality Without Surgery

It’s one thing to worry about the likelihood of dying during surgery, but what about the likelihood of dying if you don’t have surgery? And how do the two compare?

"...a morbidly obese person is much more likely to die from not having bariatric surgery than from having it."

Two studies explored these questions directly and found that…

  1. Bariatric surgery patients were 29% less likely to die than morbidly obese people who didn’t have surgery. Cancer and cardiovascular disease were the main killers of those who didn’t have surgery, both of which were less prevalent in the bariatric surgery group.2
  2. Mortality rate decreases by 40% following bariatric surgery. Those having bariatric surgery were 56% less likely to die from coronary artery disease, 92% less likely from diabetes and 60% less likely to die from cancer.3

So we now understand that gastric bypass surgery deaths are in the “middle of the road” among other bariatric procedures and that a morbidly obese person (body mass index of 35 or more) is much more likely to die over the long-term from not having surgery than from having it.

But bariatric surgery does carry a risk, so let’s get into the causes and how to minimize your chances of experiencing them…

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3 most common causes of gastric bypass surgery deaths & other risks of gastric bypass

In a meta-analysis (a study that combines many previous studies) done by the University of Iowa, 93 patients died within 30 days of surgery out of 38,501 bariatric surgery patients studied).4 The 3 leading culprits of gastric bypass surgery deaths were…

  1. Pulmonary embolism (0.078% of patients from the study) is an embolism (the sudden obstruction of a blood vessel by an abnormal particle, such as a bubble, circulating in the blood) of a pulmonary artery or one of its branches that is produced by foreign matter and most often a blood clot originating in a vein of the leg or pelvis. Its symptoms/effects include labored breathing, chest pain, fainting, rapid heart rate, cyanosis, shock and sometimes gastric bypass surgery deaths.
  2. Leaks (0.036% of patients from the study) happen when the surgical connections or staple lines made during gastric bypass surgery leak digestive contents into the abdomen. This can cause infection and abscess. This serious complication is usually repaired as long as it is caught early. Symptoms include fever, severe pain and a high heart rate. In order to prevent leaks, your surgeon should check the surgical connections made during surgery a number of different ways, including (1) blowing air into the connection and observing whether any gets through and (2) using a dye to check for a leak. Leaks not discovered right away are usually treated by resting the stomach (being fed through an IV), but sometimes surgery is required fix them.
  3. Small bowel obstruction (0.02% of patients from the study) also called an “internal hernia”, can happen anywhere from 1 to 7 years following surgery and occurs when the intestines twist and prevent the flow of food and digestive fluids. Patients with this condition usually experience abdominal pain, abdominal swelling or vomiting. A doctor will confirm the diagnosis with a CAT scan or through surgery, and surgery may or may not be needed to treat it.

Additional risks of gastric bypass include…

For more on the above along with a full list of gastric bypass complications, definitions, treatments and how they compare to other procedures, see our Bariatric Surgery Complications page.

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Minimizing the Risks of Gastric Bypass Surgery

There are 10 important steps you should take to improve your chances for a successful surgery. Click the following links for more information about each step…

  1. Educate yourself about all angles of bariatric treatment. Be mentally prepared by knowing exactly what to expect before, during and after surgery.
  2. Educate your family and close friends with a summary of your research. If they are uneducated, they are more likely to steer you off-course before or after surgery (i.e. eating tempting foods around you, not encouraging you when you need it, etc.) which can lead to complications.

    If you find that anyone is vehemently opposed to your decision, it is best to distance yourself from them, at least temporarily. Their negative influence could lead you down the wrong path during the all-important preparation, recovery and post-surgery-routine-developing stages.
  3. Lose as much weight as possible prior to surgery. The lower your body mass index before surgery, the lower your risks. (See our BMI Formula page for more about body mass index.)
  4. Eat a healthy bariatric diet both after surgery and in the months prior to surgery.

***Most Important Step***

  1. Choose good bariatric doctors and a good bariatric weight loss clinic by finding the right candidates and interviewing them with the right questions. This is the most important step by far. In fact, there is evidence that a surgeon's reoperation and rate of conversions to an open (and more dangerous) procedure drops as his total number of surgeries performed increases...
    1. Click here to find a qualified surgeon in your area
    2. Click here to learn how to evaluate and interview your bariatric doctors
  1. Stay close to your bariatric surgery center and surgeon for at least 10 days (preferably 2 weeks) after surgery. (Especially applies if you don’t have surgery near your home.)
  2. Exercise after gastric bypass surgery. Start walking as soon as possible and as your fitness level improves, work your way towards a more robust program that incorporates strength, flexibility and endurance routines.
  3. Use tools and/or medication to keep the blood flowing in your legs. See our Blood Clot Symptoms page for more details.
  4. Follow your doctor and nutritionist’s/dietitian’s advice to the letter.
  5. Have and use an effective support system before and after surgery.  In addition to friends and family, working with a good in-person weight loss surgery support group and the right online weight loss support is essential.

Go to our Complications to Bariatric Surgery page to learn more about these factors along with the ones that may be out of your control.

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References for Gastric Bypass Surgery Deaths

  1. National Institutes of Health Press Release: NIH Study Finds Low Short-term Risks After Bariatric Surgery for Extreme Obesity. July 2009. Available at:
  2. Sjöström L, Narbro K, Sjöström CD, Karason K, Larsson B, Wedel H, Lystig T, Sullivan M, Bouchard C, Carlsson B, Bengtsson C, Dahlgren S, Gummesson A, Jacobson P, Karlsson J, Lindroos AK, Lönroth H, Näslund I, Olbers T, Stenlöf K, Torgerson J, Agren G, Carlsson LM; Swedish Obese Subjects Study.
    Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007 Aug 23;357(8):741-52.
  3. Adams TD, Gress RE, Smith SC, Halverson RC, Simper SC, Rosamond WD, Lamonte MJ, Stroup AM, Hunt SC. Long-term mortality after gastric bypass surgery.
    N Engl J Med. 2007 Aug 23;357(8):753-61.
  4. Mason EE, Renquist KE, Huang YH, Jamal M, Samuel I. Causes of 30-day bariatric surgery mortality: with emphasis on bypass obstruction.
    Obes Surg. 2007 Jan;17(1):9-14.

[ 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