Medically reviewed by Meghan Maynard Harlan. Last updated on July 5, 2025
General Illness Information
Common Name:
ANAL FISTULA
Medical Term: None Specified.
Description: An abnormal channel from the anus or rectum to the skin near the anal opening but may occasionally be to another organ such as the vagina. Most fistulas begin from a deep gland in the wall of the anus or rectum. However, fistulas may sometimes result from drainage of an ano-rectal abscess. The fistula may be painful and it may discharge pus. Fistulas in infants are usually congenital and are more common in boys than girls.
Causes:
- Anal fistula can be caused by an infection, which starts in the anorectal crypts forming an abscess.
- Abscess bursts, leaving behind a tract from the interior to the anal opening.
- Other causes include injury to the anus or rectum, inflammation of the bowel (e.g. crohn’s diverticulitis) or cancer of the bowel.
Prevention: No particular preventive steps.
Signs & Symptoms
- Constant or intermittent purulent discharge.
- Firm-tender lump.
- Pain during or after bowel movement.
- Discoloration of skin surrounding fistula.
Risk Factors
- Inflammatory bowel disease, such as crohn’s disease.
- Infection (e.g. tuberculosis, diverticulitis)
- Puncture wound in anal canal lining or injury from an enema tip, injury during childbirth.
- Cancer of the bowel.
- Injection treatment for internal hemorrhoids.
Diagnosis & Treatment
- Examination may reveal one or more openings around the anus and the doctor may be able to palpate a cord-like tract. A probe may be inserted to determine the depth and the direction of the fistula.
- Anoscopy (examination of the anus with an instrument) with probing may help reveal the primary opening. Sigmoidoscopy is also required to rule out concurrent bowel disorder.
General Measures:
- Minor surgical procedure to excise fistula. Usually with local anesthetic (occasionally general anesthetic required).
- Warm sitz baths after surgery to help relieve any discomfort.
Medications:
- Stool softeners may be prescribed to prevent constipation.
- Antibiotics may be prescribed if an infection is present.
Activity:
Resume work and normal activity as soon as possible.
Diet:
Regular diet, high in fiber.
Possible Complications :
- Constipation.
- Post-surgical bowel sphincter incompetence.
- Delayed wound healing in cases of underlying bowel disorder such as crohn’s disease.
Prognosis
This condition is usually effectively treated by surgery unless underlying bowel disorder complicates it.
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