Bariatric Program

Risks of Bariatric Surgery

Bariatric surgery presents risks similar to any abdominal surgery. These risks vary depending on the medical history of each patient.

The following are some of the problems that can occur during and after bariatric surgery.

Risk of Infection and Bleeding

There are various risks of infection and bleeding that can be caused during or after bariatric surgery, such as:


Obesity causes a very deep layer of fat beneath the skin. This layer is susceptible to infection. In most cases, infection is not serious and can be resolved by reopening the incision. Less than 1.7% of bariatric surgery patients experience infection in the incision after the procedure.


After your procedure, a pocket of fluid can develop. Bacteria can cause the fluid to become infected, creating an abscess. Treatment involves draining the fluid and giving antibiotics.

Infected Bladder

In some cases, a urinary catheter is put in place to manage urine buildup, and is usually left in place for the first night after the procedure is completed. The presence of the catheter can lead to infections in the bladder, which are usually treated with antibiotics.

Hemorrhaging (Internal Bleeding)

During bariatric surgery, blood vessels are cut then stitched back together to prevent bleeding. A procedure called electrocautery is sometimes used to create a clot over the cut blood vessel. In some cases, the vessel will continue to bleed inside the abdomen or under the skin. Excessive bleeding is a risk after any surgery. Bariatric surgery has a low risk of less than 3%. If bleeding occurs, the treatments to control bleeding vary from conservative to aggressive procedures.

Risk to Your Digestive System

Because bariatric surgery makes a significant change to your digestive system, there are various risks involved, including:

Dumping Syndrome

After surgery, you may experience dumping syndrome, a condition where food passes quickly from the stomach to the intestine. Symptoms include:

  • Lightheadedness
  • Abdominal cramping and pain
  • Rapid heart rate
  • Profuse sweating
  • Nausea
  • Diarrhea

What you can do to prevent dumping syndrome:

  • Always eat your protein first.
  • Try not to eat too much at one meal.
  • Do without sweets and fried, fatty or greasy foods.
  • Avoid drinking fluids with meals.
Gastroesophageal Reflux Disease (GERD)

Gastroesophageal reflux disease, or GERD, is when food and stomach acid move back up into the esophagus, causing symptoms such as heartburn, sore throat, trouble swallowing, chronic cough and chest pain.

Weight loss following Roux-en-Y gastric bypass can help resolve GERD symptoms. Gastric sleeve can worsen symptoms in some cases. A thorough evaluation is required in patients with GERD.

Stomach Ulcers

Gastric ulcers — painful sores in the lining of your stomach or intestine — can occur after Roux-en-Y gastric bypass. The most common symptom is pain, but you may also have nausea and vomiting, trouble swallowing or bleeding.

Gastric ulcers may be treated with medications.


Internal hernias – which occur when an organ or tissue protrudes through a weak spot in surrounding tissue – can be a serious complication of bariatric surgery and may occur many months after your surgery. The main symptom is abdominal pain and tenderness.

Risk to Your Bowel

By reducing the size of your stomach and how it functions with your bowel, some complications may occur, such as:

Anastomotic Stricture

The opening between your stomach and bowel is reduced in size during Roux-en-Y gastric bypass surgery. When scar tissue forms during the healing process, this opening can become even smaller, restricting the passage of food. This condition is called anastomotic stricture, and occurs in 5 to 10 percent of cases. Treatment is usually via an endoscopy to dilate the stricture. This is done without a hospital stay.

Anastomotic Leak

When forming a connection in the gastrointestinal tract, this connection could leak and is called an anastomotic leak. Fluid may leak out of the bowel into the abdominal cavity, causing infection or abscess.

For smaller leaks, a drain may be inserted. Until the leak seals, you may not eat or drink. You would receive nutrition in alternate routes.

Bowel Obstruction

Adhesions, which bind two parts of your bowel together, can occur during any abdominal procedure. As a result, your bowel can become kinked around the adhesion, causing a blockage. In some cases, surgery may be required.

Risk to Your Lungs

Bariatric surgery has a small risk of also affecting your lungs in the following ways:

DVT and Pulmonary Embolism

Obesity paired with decreased activity and slowed blood flow from bariatric surgery increases your chance of developing a blood clot in your leg. This is called deep venous thrombosis, or DVT. Pulmonary (lung) embolism can occur when a blood clot in the leg breaks free and travels to your lungs.

Treatment includes blood-thinning medicines to help prevent clotting and compression stockings to increase the speed of blood flow in your veins. Walking is also recommended, as it improves circulation. You will be advised to walk on a regular basis beginning the night after your surgery.


Following surgery, you may develop a condition called atelectasis, when breathing may not be enough to fully inflate your lungs. This causes the tiny air passages of the lungs to close.

To help reduce the risk for atelectasis, you will learn deep breathing and coughing exercises and participate in a walking program. You will learn how to do these exercises before weight-loss surgery, and with the use of an incentive spirometer. Using an incentive spirometer helps you take slow deep breaths to avoid lung complications after surgery.


Blockages in the lungs, such as those caused by atelectasis or mucous secretions, can result in a lung infection known as pneumonia. You can help prevent pneumonia by following the breathing and coughing exercises you learn before surgery, using your incentive spirometer 10 times an hour while awake after surgery, and by walking.

Additional Risks

Other risks involved include:

Nutritional Deficiency

Your body may need help absorbing nutrients following bariatric surgery to prevent conditions such as anemia and gallstones. It’s important to follow your dietitian’s recommendations regarding vitamins and supplements after surgery, and for the rest of your life.

Low Blood Sugar

Some people develop episodes of low blood sugar, or hypoglycemia, in the years following weight-loss surgery. The episodes occur 2-3 hours after eating and may be related to a release of excessive insulin.

Symptoms of low blood sugar include feeling shaky, sweating and feeling lightheaded.


Gallstones — hard pieces of material that develop in your gallbladder — can occur following both gastric sleeve and Roux-en-Y gastric bypass. You may not have any symptoms, or may feel pain in the upper area of your abdomen.

Gallstones can block your bile duct and may cause intense pain, which is an emergency.

Skin Separation

If your wound incision is not yet healed, it may break open, causing skin separation. Your doctor may decide to let the wound heal on its own or may close the incision.

Be sure to follow your discharge instructions regarding wound care. Talk to your doctor if you notice any unusual discharge, swelling or bleeding from your incision site.

Page medically reviewed by:
Rohit Soans, MD
October 19, 2021