Fistulas are a common complication of Crohn’s disease. These are atypical tunnels which form on the intestinal walls or other organs. People with Crohn’s disease may experience fistulas forming in different parts of the intestines, with another organ, such as the bladder, or through to the skin surface.

Individuals with fistulas may experience undesirable side effects, such as:

  • diarrhea
  • pain
  • discomfort

An anal fistula is the most common type of fistula. Symptoms include a tender swelling or lump around the anus that may drain and pain that gets worse with movement.

Read this article to learn more about the different types of fistulas, including symptoms, causes, and treatment options.

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Fistulas are very common in people with Crohn’s disease, affecting 1 in 3 individuals with the condition.

A fistula is a narrow passage that occurs when inflammation causes sores, or ulcers, to form. These passages can connect one organ to another or to the outside surface of the body.

Various types of fistulas can occur in different places in the body. These include:

  • Anal (perianal): This fistula connects the anal canal or rectum to the surface of the skin close to the anus.
  • Vaginal: There are different types of vaginal fistulas, which can atypically connect the vagina to the bladder, rectum, colon, or small intestine.
  • Colovesical (bowel to bladder): A rare tract between the colon and bladder, which may allow fecal matter to appear in the urine.
  • Gastrointestinal (bowel to bowel): This fistula connects the intestine to an adjacent organ or surface.
  • Enterocutaneous (bowel to skin): An atypical tract between the intestinal tract or stomach and the skin.

Diagnosing types of fistulas

Diagnosing fistulas vary according to their type. A doctor will have to gather information, such as:

  • where the fistula opens
  • the route of the fistula
  • how many tunnels are present
  • if the fistula goes through sphincter muscles
  • if there is an infection

Read more from our IBD hub on the effects of Crohn’s.

An anal fistula is a small tunnel that develops between the end of the bowel and the skin near the anus.

Symptoms of an anal fistula include:

  • skin irritation around the anus
  • a throbbing pain that may worsen with movement, a bowel movement, or coughing
  • smelly discharge near the anus
  • passing pus or blood
  • swelling and redness around the anus
  • difficulty controlling bowel movements

These symptoms are more likely to occur in people with Crohn’s disease. Other causes may include:


To diagnose this type of fistula, a doctor will conduct a physical examination of the skin surrounding the anus, as fistulas often present as small holes or red bumps. They may also press on the skin to determine if there is a leak of puss or feces.

Medical professionals may perform the diagnosis under a general anesthetic so that the area is fully relaxed.

Sometimes, doctors use a probe to determine where the fistula travels and if it goes through sphincter muscles. Several tests can also attempt to determine this, including:

  • a pelvic MRI
  • endoanal ultrasound
  • fistulography, which involves using a dye in the anus to find signs of leakage

Often, healthcare professionals use a combination of these techniques to assess a fistula.

A vaginal fistula is a tract or hole that has opened up from the vaginal wall and connects with another organ in the body. The most common types of vaginal fistula are:

  • vesicovaginal, a tract connecting the vagina and the bladder
  • rectovaginal, a fistula connecting the vagina and the rectum
  • colovaginal, a tract that connects the vagina and the colon
  • enterovaginal, a fistula that connects the vagina and the small intestine

Symptoms can include fluid leaking from the vagina, a smelling discharge of gas from the vaginal area, or an infection in the genital area.

The fistula itself may not cause a person to experience any pain or discomfort.

However, urine, feces, or wind may pass through the vagina which can lead to incontinence issues. The continuous leakage in the vaginal area can also lead to infection or soreness.

A fistula usually develops after trauma occurs in the area, such as:


Symptoms are the most helpful for doctors to assist with diagnosing a vaginal fistula. A doctor will discuss the symptoms and any surgery, trauma, or disease that could have caused it. For a physical exam, a healthcare professional will use a speculum to look at the vaginal walls.

Similar to an anal fistula, diagnostic tests include an MRI, ultrasound, and fistulography, which involves adding dye to the vagina.

Doctors can also perform a urinalysis or blood test to check for signs of infection.

A bladder fistula, or colovesicular fistula, occurs when an opening forms between the bladder and another organ or the skin.

The most common types of bladder fistulas occur between the bladder and the bowel or between the bladder and the vagina.

Symptoms include:

This type of fistula can occur as a result of Crohn’s, injury or trauma to the bladder, bowel or gynecologic cancer, or radiation therapy.


To detect this type of fistula, a urologist will perform a physical exam and gather medical history.

Doctors may place a long and thin camera in the urethra to see the bladder — a procedure known as cystoscopy.

They may also use a test called a poppy seed test. This involves individuals eating poppy seeds — if they end up in the urine, it shows there is a fistula from the bowel to the bladder.

X-rays or CT scans can also check the bladder and surrounding areas.

A gastrointestinal (GI) fistula, or bowel to bowel fistula, connects the intestine to an adjacent organ or surface.

Digested food cannot move properly through the body if a person has a GI fistula. The fistula also may cause fluid to leak out. Symptoms can include:

Around 85–90% of GI fistulas occur due to complications with surgery. Other possible causes include:


A doctor may perform an upper and lower intestinal X-ray. They will administer barium orally or by enema before taking any X-ray images. If there are signs of leaking in the intestines, this will confirm the presence of a fistula.

A fistulogram, which involves injecting dye into the fistula area where the skin is open and leaking, can help reveal any blockages.

Read more about gastrointestinal fistulas.

An enterocutaneous fistula, or bowel to skin fistula, is an atypical connection between the intestinal tract or stomach and the skin.

As a result of this connection, contents of the stomach or intestines may leak through to the skin. Symptoms include diarrhea, dehydration, and malnutrition.

These fistulas usually occur after bowel surgery, but other causes may include:

  • perforated peptic ulcer
  • Crohn’s disease
  • abdominal injury or trauma, such as a stabbing or gunshot


Tests, such as CT scans or a fistulogram, can also help doctors diagnose this type of fistula.

A barium test, which involves individuals swallowing barium or taking it as an enema before an X-ray, can help confirm the presence of a fistula.

Treating a fistula depends on the type of fistula present and whether the individual is receiving treatment for another bowel condition. People can manage most fistulas with medication, surgical procedures, or a combination of the two.


There are different medications that doctors will prescribe to individuals with fistulas. These include:


Fibrin glue is currently the only nonsurgical treatment for anal fistulas. It involves the surgeon injecting glue into the fistula while under a general anesthetic. The glue helps seal the fistula and encourages it to heal.

This treatment is generally less effective than surgical procedures, and the results may not be long lasting. It may be a useful option for fistulas that pass through the anal sphincter muscles because they do not require cutting.


Doctors can remove fistulas can via different surgical procedures, including:

  • Fistulotomy: This is an effective strategy for treating most fistulas. However, doctors cannot perform the procedure when the fistula crosses the anal sphincter muscles.
  • Transanal mucosal advancement flap: This method involves removing the fistula and covering the hole with a flap of tissue from inside the rectum. However, this procedure has a lower success rate than a fistulotomy.
  • Ligation of the intersphincteric tract (LIFT): Doctors make a cut in the skin above the fistula and move apart the sphincter muscles. While LIFT has had some promising results so far, with fistula closure rates of 57–94%, more research is necessary to determine its short- and long-term success.
  • Plug: This is a cone-shaped plug consisting of animal tissue that blocks the internal opening of the fistula. It is a suitable alternative for simple fistulas but has a high failure rate when doctors perform this procedure in individuals with complex fistula or Crohn’s disease. The plug also has a lower risk of postoperative impairment and complications.
  • Laser surgery: This treatment involves using a small laser beam to seal the fistula. There are uncertainties around how well it works, but there are no major safety concerns.
  • Seton placement: A common treatment for anal fistulas that involves placing a seton, a thin rubber drain, in the fistula, which allows the tunnel to slowly heal. Often, doctors place a series of these over time for gradual healing.

What to expect from the procedures

Currently, none of the procedures for fistulas have a guaranteed success rate. However, the success rate of many of these procedures is generally high, with 1 in 3 of people having a fistula relapse. This means that individuals may need more than one operation to try to treat their fistula.

If a person has a fistula and is considering a surgical option, they should consult a doctor. The following are questions to ask a healthcare professional about procedures to correct fistulas.

  • What is the success rate of each surgical option?
  • What are the side effects?
  • If there is a fistula relapse, what would be the next step?
  • About how much time passes between a surgical option and a fistula relapse?
  • What can I do to help ensure the procedure is successful?

If treatment fails, a person should make an appointment with their doctor so that they can plan for alternative treatment options. Doctors may recommend another procedure or recommend allowing some time between each procedure.

They will also suggest certain lifestyle changes — according to the type of fistula a person has — to help minimize symptoms and improve quality of life.

Fistulas are not life threatening, but they can negatively impact the quality of life of those who have one.

A person should acknowledge any symptoms they may have and try to prepare in advance for their daily activities to make management easier. For example, they can try sitting on cushions or pillows if they have pain when sitting. Another option is wearing loose-fitting clothes and cotton underwear.

If a person has any questions or is in need of suggestions, they should speak with their doctor.

Atypical tunnels, called fistulas, are a common complication of Crohn’s disease.

Fistulas may go unnoticed, or they may present with symptoms, including pain, discomfort, malabsorption, diarrhea, and more.

There are many treatments to help individuals with fistulas, so if a person thinks they have one, they should schedule an appointment with a doctor so they can help diagnose and treat the condition.