Anal fistula is the medical term for an infected tunnel that develops between the skin and the muscular opening at the end of the digestive tract (anus). Most anal fistulas are the result of an infection in an anal gland that spreads to the skin. Surgery is usually needed to treat anal fistula.
Knowing the complete path of an anal fistula is important for effective treatment. The opening of the channel at the skin (external) generally appears as a red, inflamed area that may ooze pus and blood. This external opening is usually easily detected.
Finding the fistula opening in the anus (internal opening) is more complicated.Endoscopic ultrasound uses high-frequency sound waves to produce detailed images of the sphincter muscles and other structures of the pelvic floor.Fistulography is an X-ray of the fistula after a contrast solution is injected.Magnetic resonance imaging may be used for fistulas that are very difficult to find.
Fistula probe, an instrument specially designed to be inserted through a fistula. Anoscope, a small endoscope used to view the anal canal. Flexible sigmoidoscopy, a procedure to rule out other disorders such as ulcerative colitis and Crohn’s disease.
Treatment of anal fistula depends on the fistula’s location and complexity. The goals are to repair the anal fistula completely to prevent recurrence, and to avoid damaging the sphincter muscles, which can lead to fecal incontinence.
The options include:
The surgeon cuts the fistula’s internal opening, scrapes and flushes out the infected tissue, then flattens the channel and stitches it in place. To treat a more complicated fistula, the surgeon may need to remove some of the channel. Fistulotomy may be done in two stages if a significant amount of sphincter muscle must be cut or if the entire channel can’t be found.
The surgeon creates a flap from the rectal wall before removing the fistula’s internal opening. The flap is then used to cover the repair. This procedure can reduce the amount of sphincter muscle that is cut.
The surgeon places a silk string (seton) into the fistula to help drain the infection.
The surgeon clears the channel and stitches shut the internal opening. Special glue made from a fibrous protein (fibrin) is then injected through the fistula’s external opening. The anal fistula tract also can be sealed with a plug of collagen protein and then closed.
LIFT is a two-stage treatment performed for more complex or deep fistulas. LIFT allows the surgeon to access the fistula between the sphincter muscles and avoid cutting them. A seton is first placed into the fistula tract, forcing it to widen over time. Several weeks later, the surgeon removes infected tissue and closes the internal fistula opening.
The surgeon creates a temporary opening in the abdomen to divert waste into a collection bag, to allow the anal area time to heal.
In very complex anal fistulas, the channel may be filled with healthy muscle tissue from the thigh, labia or buttock.