Crohn's / IBD GastroIntestinal / Gastroenterology

What is a gastrointestinal fistula and what causes one?

A gastrointestinal fistula occurs when an abnormal connection forms between part of the gastrointestinal tract and the skin or another organ, resulting in stomach acid leaking out. Doctors may also call a gastrointestinal fistula an enterocutaneous fistula or an intestinal fistula.

A gastrointestinal fistula is a severe medical condition that may require long-term care. This article will describe the most common causes, treatments, and complications of gastrointestinal fistulae.


Intestinal fistula
An infection may cause an intestinal fistula.

Around 85–90 percent of all gastrointestinal fistulae occur as a complication of surgical procedures.

In a study of 1,148 people undergoing abdominal surgery, researchers noted that 5.5 percent of participants developed fistulae after their operation. Most fistulae appeared during the first week after surgery.

A doctor should always discuss the risks of fistulae with a person before they have abdominal surgery. They should also check in with the individual after the surgery in case they have any symptoms of a fistula, as a prompt diagnosis is likely to improve the outcome.

Other possible causes of gastrointestinal fistulae include:

  • a history of radiation to the abdomen
  • infection, such as diverticulitis
  • inflammatory bowel diseases, including Crohn’s disease
  • an ulcer in the gut
  • physical injury to the abdomen
  • cancer


When a person has a gastrointestinal fistula, digested food material cannot move properly through the body. The fistula also causes fluid to leak out, reducing levels throughout the body. Symptoms can include:

  • abdominal pain
  • dehydration
  • diarrhea
  • fever
  • malnutrition
  • raised heart rate
  • vomiting

A person with a gastrointestinal fistula can become very ill and may develop a condition known as sepsis. This is where a person’s body attacks itself as a reaction to a severe infection.

Sepsis causes a range of symptoms, such as low blood pressure, high fever, high heart rate, and organ failure. In some cases, it can even be fatal.

Doctors classify fistulae into four main categories, which may cause different symptoms:

  • Complex: This type of fistula has multiple channels that affect more than one organ.
  • External: An external fistula is one that connects a portion of the gastrointestinal tract to the skin.
  • Extraintestinal: This fistula connects part of the intestine to another organ in the body, such as the bladder.
  • Intestinal: This fistula involves the connection of one area of the intestine to another.

A person with an external gastrointestinal fistula will have an area of skin that is open. This means that acid and other contents from the stomach will leak onto the skin through the wound opening. This can be very harmful to the skin.


Barium swallow image highlighting intestine.
Barium imagining techniques can highlight the presence of a fistula.

A doctor will consider a person’s medical history when diagnosing a gastrointestinal fistula. If a person has had specific surgical procedures, including gynecologic surgery, they have a higher risk of getting a fistula.

The doctor will also ask about the person’s symptoms, including when they presented and whether anything relieves or worsens them.

If the doctor suspects a gastrointestinal fistula, they will order medical tests to confirm the diagnosis. These tests may include:

  • Imaging scans, such as a CT scan, to identify the fistula and determine its size. This is essential so that surgeons can decide where to place drains and operate.
  • Barium studies, in which the doctor will administer barium to the individual orally or by enema before taking an X-ray. If the barium reveals signs of leaking in the intestines, this will confirm the fistula’s presence.
  • Fistulogram, a diagnostic test that involves injecting dye into the area of the gastrointestinal fistula where the skin is open and leaking. This should reveal any blockages in the fistula.


Treatment for a gastrointestinal fistula depends on its severity and location.

Fistulae that are small and not infected will often close on their own.

Fistulae in the colon can take 30–40 days to close while fistulae in the small intestine are likely to take 40–50 days.

Doctors also define fistulae as high- or low-output. High-output fistulae drain more than 500 milliliters (mL) of gastric fluid a day. Low-output fistulae will drain lower quantities.

A fistula is generally more severe the more it drains because the leaking fluid can damage and infect the skin and organs that it reaches.

Surgical interventions

If a person has sepsis, a doctor will usually recommend surgery to repair the areas of drainage.

Surgery may involve special drains, negative-pressure therapy systems, or other therapies to allow the fistula to drain while healing. Negative-pressure therapy uses a vacuum to increase blood flow to an area and help drain excess fluid.

A surgeon can sometimes correct the areas of drainage using endoscopic techniques. These involve inserting a scope, which is a thin, lighted instrument, into the rectum and up to the abdominal area. It may be possible to use clips or glue to close the leaking areas of the fistula.

While this approach is less invasive than surgery, it is not possible to reach all fistulae in this manner.


Doctor handing pharmaceutical prescription of drugs or pills in bottle to patient.
A doctor may prescribe medication to reduce the amount of fluid in the gut.

The presence of food in the gut triggers the additional secretion of gastric juices, preventing a person with a fistula from getting enough nutrients.

A lack of nutrition will make it difficult for a person’s body to heal. Therefore, alongside surgical treatment, a doctor will often recommend alternative forms of nutrition while the gut heals.

For example, they may recommend total parenteral nutrition (TPN), which involves administering nutrients via a central intravenous (IV) line.

A doctor may also prescribe medications to reduce stomach fluid and saliva. This will reduce the amount of fluid in the gut. Examples include:

  • glycopyrrolate or scopolamine to decrease saliva production
  • proton-pump inhibitors, such as omeprazole (Prilosec), which reduce acid secretions
  • H2-receptor antagonists, such as famotidine (Pepcid) or ranitidine (Zantac), which also reduce stomach acid
  • anti-diarrheal drugs, such as loperamide or codeine phosphate

A doctor will sometimes give medications that are chemically similar to the hormone somatostatin, such as octreotide and lanreotide. This hormone can significantly reduce gastrointestinal secretions, which can help the fistula to heal.

While this therapy is not right for everyone, it can help some people reduce their symptoms without experiencing as many side effects.


A gastrointestinal fistula can lead to various complications, which include:

  • infection
  • malnutrition
  • electrolyte imbalances
  • poor wound healing

Around 25 percent of fistulae will heal within 30–40 days with correct nutrition and some medical management. However, the mortality rate for all gastrointestinal fistulae can be as high as 40 percent. As such, it is important for people to seek immediate treatment for this condition.


A gastrointestinal fistula can be a severe condition that may spontaneously resolve but can sometimes require treatment.

When a fistula does occur, it can take a significant amount of time to get better. However, with medications and nutrition management, most people will be able to heal the affected area.

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