Fistula-in-ano is a relatively common condition usually occurring between the ages of 30-60 years. Males tend to be more susceptible than females.
What is an ano-rectal fistula?
An ano-rectal fistula is a track between the rectum and perineum with an opening at each end, and is usually caused by an abscess beside the anus. After the abscess discharges pus, a track remains from inside the anus to the skin through the gland and abscess cavity.
Causes of ano-rectal fistula
- The most common cause of ano-rectal fistula is the penetration of pus from an infected anal gland. An abscess from an infected anal gland presents as a painful red swollen lump, like a boil next to the anus which may spread into the buttock.
- Perineal injuries such as those received during a fall, from a road traffic injury or from a tear during childbirth may also result in the formation of an ano-rectal fistula.
Management of the fistulous track
- Insertion of a Seton for drainage: A Seton is a narrow silicone band which is passed through the fistulous track and tied outside the anus. The Seton then acts as a drain to allow pus to escape and therefore help settle infection. When successful this method may avoid the need for surgical intervention, but often a further procedure is required to heal the fistula after infection has settled.
- Laying open of the fistulous track: The track is excised and the lining is scraped away leaving new healthy tissue to promote the healing process.
- The formation of a rectal mucosal flap: The fistula is excised and a flap of healthy rectal mucosa is stitched over the internal opening to close it off. This method occasionally requires the formation of a temporary colostomy to rest the bowel while healing takes place.
- Ligation (tying off) of the fistulous track between the sphincter muscles (LIFT procedure).