An anal fistula is a small channel (or tract) that develops between the end of the bowel, known as the anal canal, and the surrounding tissue (near the anus. The end of the fistula can appear as a hole in the skin near the anus.

Anal fistulas are usually classed as either:

•  Simple or complex – depending on whether there is a single fistula tract or interlinking connections
• Low or high – depending on its position and how close it is to the sphincter muscles (the rings of muscles that open and close the anus)

What causes an anal fistula?

An anal fistula usually develops after an anal abscess (a collection of pus) but can occur spontaneously. A fistula can also be caused by conditions that affect the intestines, such as inflammatory bowel disease (IBD) or diverticulitis. An anal fistula may also develop as a result of:

• A growth or ulcer (painful sore)
• A complication of surgery
• A health problem you were born with.

Symptoms of an anal fistula

There are several common symptoms of an anal fistula.

Symptoms include:

• Skin irritation around the anus
• A throbbing, constant pain that may be worse when you sit down, move around, have a bowel movement or cough
• A discharge of pus or blood when you have a bowel movement 

If your fistula was caused by an abscess that you still have, you may have:

• Fever
• Fatigue
• A general feeling of being unwell.

Treating an anal fistula

Surgery is needed to heal a fistula, the course of the tract between the anus and the skin has to be identified and debrided. This tract may be treated using one or a combination of three methods according to its complexity.

• Fistulotomy opens the length of the tract to the skin’s surface allowing the open wound to heal slowly. Some sphinter muscle is divided.
• A Seton is a loop of flexible material placed along the tract to maintain drainage for a period of time and allow inflammation to settle and the area to soften so that a repair may be attempted.
• Fistula repair closes the internal opening of the tract and preserves anal sphinter muscle. During surgery, the fistula tract is debrided (unhealthy tissue removed). A flap of healthy anal tissue is then attached to the internal opening of the fistula. Fistula repair is a delicate procedure and successful healing is achieved in about 60% of operations.

If the flap repair fails the fistula may require further management with a Seton and or repeat flap repair.

Recovering from surgery 

If the fistula is relatively simple to operate on, you may be able to go home on the same day as the surgery or discharge the next day. You can take regular panadol for pain and will be given a stronger analgesic to take as needed.

You may need 1-2 weeks off work depending on comfort level.

Looking after the wound

There may be some bleeding or a discharge from the wound for the first couple of weeks. You may wish to wear a pad, such as a sanitary towel, inside your underwear to avoid staining your clothes. This advice applies to both men and women. You should contact us if you have:

• Persistent bleeding
• Increasing pain, not relieved with analgesia
• Fever
• Nausea or vomiting (that doesn’t settle)
• Constipation – being unable to empty your bowels for more than three days, despite using a laxative
• Difficulty passing urine

The following tips help keep the area around the fistula clean, prevent irritation and promote healing;

• Have a warm bath (sitz bath), a tablespoon of salt can be added to bath, pat the skin dry rather than rubbing it, or use a hairdryer on a low setting
• Have a sitz bath or shower 2-4 times a day (timing after bowel motions)
• Avoid perfumed products and talcum powder as these can irritate the skin around the fistula
• Avoid excessive physical activity and sitting for prolonged periods in the first few weeks post operatively
• Avoid constipation and straining, you can take regular benefiber to prevent constipation and the laxative macrogol as needed to get bowels moving.