About Anal Fistula
An anal fistula is a track between the skin on the outside and the anal canal on the inside. There are many different types of fistula, from relatively simple to a complex branching network of tracks. Some involve the muscles responsible for bowel control. Each one is individual but is almost always the result of a previous abscess.
What causes a fistula?
After an abscess has been drained, a tunnel or track may persist, connecting the anal gland from which the abscess arose to the skin. If this occurs, persistent drainage from the outside opening may indicate the persistence of this tunnel. If the outside opening closes, recurrent abscesses may develop.
Does an abscess always become a fistula?
No. A fistula develops in about 50% of all abscess cases, and there is really no way to predict if this will occur. Dr Renaut will see you at about a week 4 weeks to assess whether this has occurred.
What are the symptoms of a fistula?
Sometimes nothing, but usually persistent minor discomfort, irritation and drainage of pus or blood form the external opening. Occasionally a recurrent abscess can develop.
What about treatment for a fistula?
Surgery is necessary to cure an anal fistula. Fistula surgery usually involves laying open the whole length of the fistula tract (fistulotomy) effectively joining the external and internal openings, and converting the tunnel into a shallow wound that will then heal from the base. This is only permissible if the fistula is "low" ie it involves only a minimal amount of the sphincter muscle. If it is "high" then too much of the muscle is involved rendering a fistulotomy unsafe ie there is a significant risk of incontinence. Under these circumstances a special fine drainage tube, called a seton, is placed through the tract that allows proper drainage to take place. Whether a fistula is suitable for a fistulotomy or whether it requires a seton can often only be assessed at the time of surgery.