An anal fistula is a tract that connects the inside of the lower bowel or anus to the skin of perineum. A fistula is most commonly the result of an abscess around the anus which has either been surgically drained or burst. It can also occur in patients with Crohn’s disease or more rarely in patients having surgery that involves a join low down on the bowel, such as after rectal cancer surgery or following ileal pouch surgery.
An anal fistula can lead to recurrent abscesses in the same area, or an ongoing creamy discharge from around the anus. During a flare of symptoms there may be pain around the anus which may become worse when opening your bowels.
Fistulas can be broadly classed as simple or complex. Simple fistulas do not usually involve much thickness of the anal muscles and can usually have tract opened up under a general anaesthetic. It will normally take a couple of months for the wound to completely heal, but will usually result in complete cure of the fistula.
A complex fistula typically involves a greater thickness of anal muscles. It is common to insert a thread, known as a seton, through the tract to help drain any infection before an attempt at curative surgery.There are a number of different procedures for complex fistulas including the LIFT procedure and advancement flaps. Unfortunately, these complex fistulas are at higher risk of recurring and may require several procedures to achieve this. The best approach will vary depending on the complexity of the fistula.
In patients with Crohn’s disease, surgical intervention is best kept to a minimum. This is to try and minimise the risk of damage to the anal muscles. Fistulas are more commonly managed with setons to drains any infection together medical management with biological drugs (e.g. infliximab). This requires a joint approach from a gastroenterologist and a surgeon with an interest in inflammatory bowel diseases.