Anal fistula is an infected tunnel connecting the skin on the buttock to an internal part of the anus. This fistula usually forms as a result of an inflammation of one of the glands in the anus.
- The most common cause of anal fistula is an infection of an anal gland or an anal abscess.
- Less commonly, it can occur as a complication of Crohn’s disease which affects the intestines, or diverticulitis (is small, bulging sacs of the inner lining of the intestine that become inflamed or infected)
- It may be seen in tuberculosis, a sexually transmitted infection or after trauma.
- The opening on the skin will most likely be red, inflamed and oozing blood or pus.
- There may be pain or swelling or bleeding while passing stools.
- There may be a history of having anal abscesses in the past.
- Fever, chills and fatigue may be present.
A history of pain, swelling and discharge from the skin near the anus combined with a thorough examination including an anoscopy (examination of the anal canal using an instrument called proctoscope and a light source) confirms the diagnosis.
All routine blood, urine, stool tests including a chest X ray, ECG and bloods sugars if you are diabetic are done before the surgery.
A colonoscopy is advised if your doctor suspects that you have Crohn’s disease.
An ultrasound or MRI may be needed to determine the exact location of the fistula.
Surgery is the only method to treat an anal fistula. Antibiotics will help control the infection but the infection will recur as long as the tunnel or tract is left open. Fistula surgery is done as an outpatient procedure but very deep fistulas may require a short hospital stay.
The fistula has to be opened so that healing can occur. The two ends of the tunnel, namely the skin end and the anal end, have to be identified. The skin end is easy to locate while the anal opening is sometimes difficult to find. It is important not to cut the muscles which form the anal sphincter, otherwise incontinence of stool may occur after the surgery.
Fistulotomy – The tissue has to be dissected continuously at the roof of the tunnel from one end and it must be laid open so that it is no more a tunnel. Then, the tract must heal from inside. Complete healing after surgery may take a few weeks. A scar will be visible at the site of the fistula
Ligation of the Intersphincteric Tract Surgery (LIFT) – If the fistula is complex, a special drain called seton is inserted into the tunnel and another surgery is scheduled for a later time. In the second surgery, the infected tunnel is opened and the internal opening in the anus is closed.
Advancement rectal flap – A flap is created from the tissue of the rectum higher up. This flap is then used to cover the anal opening. This reduces the cuts to the anal musculature.
Muscle flap – In this procedure, the fistula is stuffed with healthy tissues from the thigh or buttock. This is done in complex cases.
After the operation, you will be advised to soak the area in a warm bath a few times a day. Painkillers are given to ease discomfort in the area. Laxatives or stool softeners may be required for the first few days for easy passage of stools.