A gastrointestinal fistula (GIF) is an abnormal opening in your digestive tract that causes gastric fluids to seep through the lining of your stomach or intestines. If you have a GIF, you’re more at risk for infection when these fluids leak into your skin or other organs.

GIF usually happens after intra-abdominal surgery, which is surgery inside your abdomen. But if you have chronic digestive problems, you also have a high risk of developing a fistula.

There are several different causes of GIFs. They include:

Surgery complications

About 85–90 percent of GIFs develop after intra-abdominal surgery. You’re more likely to develop a fistula if you have:

  • cancer
  • radiation treatment to your abdomen
  • a bowel obstruction
  • surgical suture problems
  • incision site problems
  • an abscess
  • an infection
  • a hematoma, or blood clot under your skin
  • a tumor
  • malnutrition

Spontaneous GIF formation

A spontaneous GIF forms in about 10–15 percent of cases, often as a result of things like inflammatory bowel disease, malignant tumors, or bowel infections like diverticulitis.

Inflammatory bowel diseases, such as Crohn’s disease, can also cause GIFs. As many as 40 percent of people with Crohn’s disease develop a fistula at some point in their lives.

Vascular insufficiency (inadequate blood flow) is another cause.


Physical trauma, such as gunshot or knife wounds that penetrate the abdomen, can also cause a GIF to develop.

External fistulas cause discharge through the skin. They’re accompanied by other symptoms, including:

  • abdominal pain
  • painful bowel obstruction
  • fever
  • elevated white blood cell count

People who have internal fistulas may experience:

  • diarrhea
  • rectal bleeding
  • a bloodstream infection or sepsis
  • poor absorption of nutrients and weight loss
  • dehydration
  • worsening of the underlying disease

There are four main types of GIFs:

  • Intestinal fistula. With this form of fistula, gastric fluid leaks from one part of the intestine to the other where the folds touch.
  • Extraintestinal fistula. This type of fistula occurs when gastric fluid leaks from your intestine to your other organs, such as your bladder, lungs, or vascular system.
  • External fistula. In this case, gastric fluid leaks through the skin. It’s also known as a “cutaneous fistula.”
  • Complex fistula. This type of fistula occurs in more than one organ.

The most serious complication of GIF is sepsis, a medical emergency in which the body has a severe response to bacteria. This condition may lead to dangerously low blood pressure, organ damage, and death.

Since surgery or underlying disease usually cause a GIF, the condition itself can be a complication.

Your prevention strategy will depend on the cause and the type of fistula. When the cause is a serious illness or injury, prevention is immediate treatment.

If the cause is another underlying condition, prevention may be about finding the best treatment or management strategies for the condition itself.

The reality is that you may not always be able to predict a gastrointestinal fistula before it develops. However, you can take steps to prevent GIF before surgery.

In this case, doctors will likely want you to eat healthy before the surgery in the appropriate timing, take medications to reduce acid in the stomach, take antibiotics as a precaution to prevent surgical infections, and empty the stomach before the procedure.

Another important prevention strategy is treating all surgical complications immediately as they happen.

Contact your doctor if you experience any of these symptoms:

  • a significant change in your bowel habits
  • unusual or severe weight loss
  • fever
  • severe diarrhea
  • fluid leakage from an opening in your abdomen or near your anus
  • unusual abdominal pain

There may be many causes for these symptoms. If your doctor doesn’t already suggest it, tell them if you’re at risk for a gastrointestinal fistula. If you have a history of inflammatory bowel problems, or you’ve recently had surgery, you’re at a higher risk.

Your doctor will first review your medical and surgical history and assess your current symptoms. After that, they might do the following:

  • Run blood tests. These will assess your serum electrolytes and nutritional status, which measures the levels of albumin and pre-albumin. These are both proteins that play an important role in wound healing.
  • Perform an upper and lower endoscopy. Your doctor may use this test to view possible problems in your digestive or gastrointestinal tract with an endoscope.
  • Perform an upper and lower intestinal X-ray. This may include a barium swallow if your doctor thinks you might have a stomach or intestinal fistula, or a barium enema if your doctor thinks you have a colon fistula.
  • Perform a fistulogram. This involves injecting a contrast dye into the opening of your skin in an external fistula and then taking X-ray images.

Fistulas are classified based on how much gastric fluid is seeping through the opening. Low output fistulas produce less than 200 milliliters (mL) of gastric fluid per day. High output fistulas produce about 500 mL per day.

Fistulas close on their own when:

  • your infection is controlled
  • your body is absorbing enough nutrients
  • your overall health is good
  • only a small amount of gastric fluid is coming through the opening

Doctors will treat most fistulas nonsurgically because 70–90 percent of fistulas will close on their own within 5 weeks of treatment. Treatment focuses on keeping you well-nourished and preventing wound infection.

Treatments may include:

  • replenishing your fluids
  • correcting your blood serum electrolytes
  • normalizing an acid and base imbalance
  • reducing the fluid output from your fistula
  • controlling infection and guarding against sepsis
  • protecting your skin and providing ongoing wound care

Your doctor may recommend surgically closing your fistula if you haven’t improved after 3 to 6 months of treatment.

Fistulas close on their own about 70–90 percent of the time without surgery in people who are otherwise healthy and when they produce small amounts of fluids.

GIFs most often develop after abdominal surgery or as a result of chronic digestive disorders. Talk with your doctor about your risks and how to spot symptoms of a developing fistula.