Aliments – Anal Abscess, Anal Fistula

An anal abscess is a cavity found near the anus or rectum that has been infected and filled with pus. The pus may discharge if the skin over the abscess breaks. This is often confused with haemorrhoids (piles).

An abscess typically results from a severe infection of a small gland, located just inside the anus. This occurs when bacteria or foreign matter enters the tissue through the gland. Certain conditions (e.g. inflammation of the intestine or colitis) can make these infections more likely.

An anal fistula is a small tunnel under the skin that connects a previously infected anal gland to the skin on the buttocks outside the anus. It is almost always the result of a previous abscess.

After draining an abscess, a tunnel may persist in connecting the anus or rectum to the skin. Persistent drainage of mucous or pus may suggest the presence of this tunnel. If the opening on the outside of the tunnel heals while the cavity on the inside remains, a recurrent abscess may form.

Symptoms of either ailment include constant pain, occasionally accompanied by swelling that may not be related to bowel movements. Other symptoms include fever and discharge of pus, which usually relieves the pain.

No. A fistula develops about half the time, but there is no way to predict if this will occur. Occasionally, the fistula is already present at the time of presentation of the abscess, but cannot be located owing to the swelling of tissue in the area.

The treatment for an abscess is a minor operation, which involves making an opening in the skin over the abscess to drain the pus from the infected cavity. The skin opening is left to heal after the operation, and the wound needs to be cleaned daily.

A deep or large abscess may require surgery under general anaesthesia and hospitalisation. Antibiotics are a poor alternative in treating the abscess, because its effects cannot reach the fluid within an abscess.

To cure an anal fistula, surgery is required. Although fistula surgery is fairly straightforward most of the time, the likelihood for complications exists. Preferably, it should be performed by a colorectal surgery specialist.

Fistula surgery normally involves cutting a small section of the anal sphincter muscle, so as to open the tunnel and convert it into a groove that will then heal outwards. If a large section of the muscle is involved, your surgeon may opt to first leave a suture (stitch) in the fistula, leaving till a second operation to cut the muscle. The surgery needs to be performed with care, as cutting too much muscle will lead to loss of bowel control (faecal incontinence). Fistula surgery can be performed on an outpatient basis in the day surgery centre, or with a short hospital stay most of the time.

Patients can usually be discharged on the same day, or one day after surgery. Discomfort may range from mild to moderate in the first week, but this can be controlled with painkillers.

Patients may need to rest at home for a period of time, visiting a family clinic daily to dress the wound initially. To prevent soiling of clothes, patients can opt to wear a gauze pad or mini-pad. While bowel movements will not affect healing, stool softeners may be recommended.

The problem will usually not return if the wound heals properly. It is important to follow your doctor’s directions to prevent recurrence.