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What is a fistula?

Fistula is a word we hear closely connected to stoma surgery, but only a small number of ostomates will be affected by them.

Some may develop them in their gastro-intestinal tract following stoma surgery and others may have them specifically formed by their surgeon alongside their stoma, as part of the surgery itself known as a mucus fistula.

Here is some more information for you to understand the types of fistulas which can affect ostomates, symptoms to look out for and what can be done to treat them.

What is a fistula?

A fistula is an abnormal passageway or tunnel in the body. An internal fistula is an abnormal tunnel between two organs and an external fistula is abnormal tunnel between an internal organ and the outside of the body.

Fistulas are usually the result of an injury or surgery, and infections or inflammation can also cause a fistula to develop.

They sound scary, but the good news is, if they are managed, they can often be treatable. Fistulas close on their own about 70–90 percent of the time without surgery in people who are otherwise healthy and if they produce small amounts of fluid.

Gastro-intestinal fistulas most often develop after abdominal surgery or as a result of chronic digestive disorders. Talk with your doctor about your risks, how to spot symptoms of a developing fistula and get support from your stoma care nurse if you have a fistula which needs monitoring.

Fistulas can often be quite tricky to manage due to their acidic output and therefore the skin around them needs to be cared for to make sure it doesn’t not get sore.

Causes of fistulas

Fistulas form when inflammation causes sores or ulcers to form on the inside wall of the intestine or nearby organs. Those ulcers can extend through the entire thickness of the bowel wall, creating a tunnel to drain the pus from the infected area.  An abscess or a collection of pus, can also cause one to develop.

Most gastro-intestinal fistulas develop after intra-abdominal surgery. You’re more likely to develop one if you have:

  • Abdominal and stoma surgery
  • Inflammatory bowel disorders such as Crohn’s disease
  • Medical conditions such as ulcers, pancreatitis, or cancer
  • Radiation treatment in the abdomen
  • Abdominal trauma such as a stab wound


Different types of fistulas associated with stomas

There are different types of fistulas. It is important to understand that some are developed intentionally by the surgeon during stoma formation surgery such as a mucus fistula.

Other types associated with stoma surgery are gastro-intestinal fistula, which develop on their own and result in an abnormal opening in your digestive tract which causes gastric fluid to seep through the lining of your stomach and intestines.

What is a mucus fistula

When surgery is performed to remove part of the bowel and a stoma is formed, the disconnected part of the bowel will continue to produce gas and mucous. A mucus fistula allows this gas and mucous to leave the body and be collected in a stoma bag. This means there will be two stomas, this being known as a distal mucus fistula.

When an ostomate has a loop ileostomy or colostomy, then a mucous fistula will not be required as one side of the loop discards food from your body and the other loop discards the mucus.

What is a gastro-intestinal fistula

A gastro-intestinal fistula is an abnormal opening in your stomach or intestines. Fluids from your stomach and intestines leak into other parts of your body through the opening. They can leak into other organs or through your skin to the outside of your body. These can lead to infections, malnutrition (not enough calories or nutrients), or dehydration.

A spontaneous gastrointestinal fistula forms in about 10–15 percent of cases, often because of inflammatory bowel disease, malignant tumours, or bowel infections like diverticulitis.

Inflammatory bowel diseases, such as Crohn’s disease, can also cause gastro-intestinal fistulas. As many as 40 percent of people with Crohn’s disease develop one at some point in their lives.

Symptoms of a fistula

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

  • Abdominal pain
  • Painful bowel obstruction
  • Fever
  • Elevated white blood cell count

People who have internal fistulas may experience:

  • Diarrhoea
  • Rectal bleeding
  • A bloodstream infection or sepsis
  • Poor absorption of nutrients and weight loss
  • Dehydration
  • Worsening of the underlying disease



 Doctors will treat most fistulas non surgically 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 for gastro-intestinal fistula may include:

  • Antibiotics
  • Immune suppressing medicines if the fistula is a result of Crohn’s disease
  • Surgery to remove the fistula and part of the intestines if the fistula is not healing
  • Nutrition through a vein while the fistula heals (in some cases)

Speak to your stoma nurse for support. You will be given guidance on whether a small stoma bag or dressing is required depending on the amount of output from the fistula. Skin hygiene and protection of the surrounding skin is important to prevent soreness.  Often barrier sprays or wipes can be used in order to protect the skin from the acidic output.

For more information and advice, visit out stoma care advice centre.

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