What is a fistula?

A fistula is an irregular passageway or connection between an organ, vessel or part of the intestine and another structure, which may be caused by injury or develop as a result of surgery. There are different types of fistula and they can develop all over the body. Fistula affecting the digestive system can be internal or external. Internal fistula develop between two parts of the digestive system, while external fistula develop between an organ in the digestive system and the exterior of the body. Fistula can be simple, involving just a single tract, or much more complex, involving several tracts which may spread out.

Types of fistula

Fistula can develop in many areas of the body, and include:

  • Biliary: these connect the bile ducts to the skin.
  • Arteriovenous: these occur between arteries and veins.
  • Umbilical: these occur between the tummy button (the naval) and the gut.
  • Anal (also known as faecal): this causes faeces to be discharged through a different opening to the anus.
  • Cervical: this can mean an abnormal opening in the cervix or a fistula in the neck area.
  • Gastric: this type of fistula occurs from the stomach to the surface of the skin.
  • Craniosinus: this occurs between the skull and sinus in the nasal area.

Most commonly fistula develop in the anus, small bowel and colon. The most widespread forms of fistula include:

  • Ileosigmoid: between the ileum and the sigmoid portion of the colon.
  • Anorectal: between the anal canal and anus.
  • Cutaneous: between the small bowel or colon and the surface of the skin.
  • Colovesical: between the bladder and the colon.
  • Anovaginal: between the anus and the vagina.
  • Ileocecal: between the ileum and the caecum.

What causes a fistula?

Fistula can develop during gestation, which means a baby will be born with a congenital fistula. Congenital fistula is more widespread in boys than girls.

Fistula can also develop as a result of injury or following surgery. Fistula can also be caused by illnesses and infections; for example, the most common cause of anal fistula is an anal abscess. Fistula in the intestine can develop as a result of inflammatory bowel disease, Crohn’s disease (around 25% of people with Crohn’s disease develop fistula) and ulcerative colitis, irritable bowel syndrome and diverticulitis. Other conditions, including HIV and AIDS, tuberculosis, cancer and sexually transmitted infections, such as Chlamydia and syphilis, can also increase the risk of developing a fistula.

Symptoms of a fistula

Symptoms of a fistula include:

  • Pain.
  • Fever (high temperature).
  • Itching.
  • Tenderness around the area.
  • Generally feeling unwell.
  • Draining pus.

The symptoms tend to vary according to the severity of the fistula and the affected area of the body. In some cases an individual may not experience symptoms if they have a fistula, with the condition being diagnosed during tests for another condition.

How is a fistula diagnosed?

There are various tests that can be used to diagnose a fistula. These include a physical examination for an external fistula and a colonoscopy or CT scan for an internal fistula. A colonoscopy is a test used to allow doctors to see the inside of the body and involves passing a thin, flexible tube called an endoscope through a natural opening of the body (such as the mouth or the anus) and passing it into the area of the body which is being examined. The colonoscope has a light and a camera, which sends images to a monitor and allows doctors to see any abnormalities, obstructions or signs of health conditions. A CT (computerised tomography) scan uses computer technology and X-rays to generate very detailed mages of the inside of the body.

Treatment for a fistula

In some cases fistula heal of their own accord but there are treatments available, including medication (usually antibiotics) and surgery. Surgery is usually carried out if other treatments do not work, with the aim of surgery to heal the fistula. If a fistula develops in a section of the bowel, a procedure may be carried out to remove the diseased portion of the bowel and reconnect the remaining parts, which may also require a temporary ileostomy or colostomy procedure.

In most cases a fistula heals fully with the right treatment and should not recur. It is rare for complications to develop as a result of a fistula and complications are usually caused by surgery to treat the fistula. Possible complications of surgery include:

  • Infection: all surgical procedures carry a risk of infection, although doctors and nurses do everything they can to make the risk as low as possible.
  • Incontinence: in the case of surgery for anal fistula the operation can cause incontinence.
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