Weight Loss Surgery

The Top 3 Mortality Risks Associated with Bariatric Surgery & How to Avoid Them

As with any major surgery, risks exist but are potentially avoidable. Your level of risk depends on many factors, ranging from hereditary issues to what type of drugs you are taking, and varies according to the type of weight loss surgery you choose.

This page focuses specifically on mortality risk (risk of death) and how to reduce it. Our Bariatric Surgery Complications page reviews all bariatric surgery risks, complications and side-effects for each type of weight loss surgery.

Note that this page reviews the mortality risk of the more invasive procedures including gastric bypass, gastric sleeve, gastric banding (Lap Band) and duodenal switch. It does not pertain to the gastric balloon procedure which is non-invasive and therefore carries a lower mortality risk.


Click on any of the topics below to jump directly to that section

  1. Mortality Risks
  2. Complete List of Risks & Complications
  3. Patient Experience and Expert Advice
  4. Find a Weight Loss Surgeon
Bariatric Surgery Source

Mortality Risks Associated with Bariatric Surgery


  • 3 complications (pulmonary embolism, anastomotic leaks, and respiratory failure) are responsible for 80% of deaths (read details below)

“About 80% of the deaths that occur within 30 days of surgery are the result of pulmonary embolism, anastomotic leaks or respiratory failure.”

Obesity-related health problems are far riskier than bariatric surgery: morbidly obese patients who receive bariatric surgery are 89% less likely to die than morbidly obese individuals who don’t have surgery (1).

Still, as with any major surgery the risk of death is rightfully the biggest fear for every bariatric surgery patient. Of the less than 0.135% of patents who die within 30 days of surgery (2), about 80% of them are the result of pulmonary embolism, anastomotic leaks or respiratory failure (3).

  • Pulmonary embolism as a result of bariatric surgery is usually caused by deep vein thrombosis (DVT). DVT occurs when a person develops a blood clot in one of the body’s deep veins. If the clot breaks free from the vein, it can travel to the lungs and block a pulmonary artery or one of its branches. DVT can cause labored breathing, chest pain, fainting, rapid heart rate, cyanosis, shock and sometimes death.
  • To avoid blood clots (and therefore DVT which can lead to pulmonary embolism), doctors will use blood thinners and special equipment that squeezes the lower legs to keep the blood flowing. Your surgeon will also try to get you up and walking around as soon as possible after surgery.
  • Be sure to tell your doctor whether you or anyone in your family has a history of clotting, as either can increase your risks.
  • Smoking also increases the risk of blood clots (in addition, if you are having laparoscopic gastric bypass surgery smoking can cause painful ulcers). The effects of smoking on your surgery risks in general – including blood clots – can last more than 6 weeks after your last inhalation of smoke, so the sooner you quit before surgery, the better.

For more information, see our Blood Clot Symptoms, Treatments & Prevention page.

  • Anastomotic leaks – anastomotic leaks happen when the surgical connection made during bariatric surgery leaks digestive contents into the abdomen which can cause infection and abscess (a localized collection of pus surrounded by inflamed tissue that is drained through surgery or percutaneously (through the skin)). This serious complication occurs in as many as 5% of patients and can be repaired as long as it is caught early. Symptoms include fever, severe pain and a high heart rate.
  • In order to prevent them, your surgeon should check the 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 occasionally surgery is required to repair them.
  • Respiratory failure is another rare but serious complication. It occurs when oxygen and carbon dioxide levels fall too far outside of their normal ranges. Your bariatric doctors will keep an eye on this and, if necessary, will treat you with drugs and ventilation, among other techniques.

Certain conditions and drugs can also increase your bariatric surgery risks (mortality risks), including…

  • NSAIDs (non-steroidal anti inflammatory drugs including ibuprofen, Aleve, etc.) which are often taken for arthritis
  • Crohn’s disease (an inflammatory disease of the intestines)
  • Ulcerative colitis (another type of inflammatory bowel disease)
  • High blood pressure
  • Diabetes, chest pain or both high blood pressure and high cholesterol. If you have any of these, you’ll most likely need cardiac clearance before the surgery will be approved.
  • Excessive scar tissue from previous intestinal or hernia surgeries could make the operation more difficult. Be sure to let your doctor know about all previous surgeries.
  • The higher your body mass index, the higher your risk. Lose as much weight as possible prior to surgery with an appropriate bariatric diet and weight loss surgery exercise program.

Good bariatric doctors will review each of the above with you to outline your specific risks and to help you choose the surgery that best fits your situation (complications by procedure are reviewed on our Bariatric Surgery Complications page).

Your surgeon may also have access to the Obesity Surgery Mortality Risk Score (OS-MRS), a test developed by a weight loss surgery program director from North Carolina. The OS-MRS evaluates a number of factors to determine your weight loss surgery risk level. In addition to a few of the points above, the test’s developers also determined that being male and being over the age of 46 increase your risks (4).


Complete List of Risks & Complications Associated with Bariatric Surgery


  • Overall complication rate is about 9%

A recent study by the Department of Health & Human Services’ (HHS) Agency for Healthcare Research and Quality (AHRQ) found that overall complications following bariatric surgery dropped 9% in 4 years (5).

For a complete list of complications by surgery, treatments, risk factors and how to reduce your risk of complications see our Bariatric Surgery Complications page.

Bariatric Surgery Source

Patient Experience and Expert Advice


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