(See also Evaluation of Anorectal Disorders Evaluation of Anorectal Disorders The anal canal begins at the anal verge and ends at the anorectal junction (pectinate line, mucocutaneous junction, dentate line), where there are 8 to 12 anal crypts and 5 to 8 papillae. The... read more .)
Fistulas arise spontaneously or occur secondary to drainage of a perirectal abscess. Most fistulas originate in the anorectal crypts. Other causes include
Fistulas in infants are congenital and are more common among boys.
Rectovaginal fistulas may be secondary to Crohn disease, obstetric injuries, radiation therapy, or cancer.
Symptoms and Signs of Anorectal Fistula
A history of recurrent anorectal abscess Anorectal Abscess An anorectal abscess is a localized collection of pus in the perirectal spaces. Abscesses usually originate in an anal crypt. Symptoms are pain and swelling. Diagnosis is primarily by examination... read more followed by intermittent or constant discharge is usual. Discharge material is purulent, serosanguineous, or both. Pain may be present if there is infection. On inspection, one or more secondary openings can be seen. A cordlike tract can often be palpated. A probe inserted into the tract can determine the depth and direction and often the primary opening.
Diagnosis of Anorectal Fistula
Sometimes anoscopy, sigmoidoscopy, or colonoscopy
Diagnosis of anorectal fistula is by examination. Anoscopy or sigmoidoscopy may be used to visualize the internal opening of the fistula. Colonoscopy should follow if there is suspicion of Crohn disease (see diagnosis of Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more ).
Hidradenitis suppurativa Hidradenitis Suppurativa Hidradenitis suppurativa is a chronic, scarring, acnelike inflammatory process that occurs in the axillae, groin, and around the nipples and anus. Diagnosis is by examination. Treatment depends... read more , pilonidal sinus Pilonidal Disease Pilonidal disease refers to an acute abscess or chronic draining sinus in the sacrococcygeal area. (See also Evaluation of Anorectal Disorders.) This photo shows a midline pilonidal cyst with... read more , dermal suppurative sinuses, and urethroperineal fistulas must be differentiated from cryptogenic fistulas.
Treatment of Anorectal Fistula
Various surgical procedures
Medical treatment if caused by Crohn disease
(See also the American Society of Colon and Rectal Surgeons' clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula.)
In the past, the only effective treatment was surgery, in which the primary opening and the entire tract are unroofed and converted into a “ditch.” Partial division of the sphincters may be necessary. Some degree of incontinence may occur if a considerable portion of the sphincteric ring is divided. Alternatives to conventional surgery include advancement flaps, biologic plugs, and fibrin glue instillations into the fistulous tract. More recently, the ligation of intersphincteric fistula tract (LIFT) procedure, where the fistula tract is divided between the sphincter muscles, has gained acceptance as an alternative more likely to preserve continence.
If diarrhea or Crohn disease is present, fistulotomy is inadvisable because of delayed wound healing. For patients with Crohn disease, metronidazole, other appropriate antibiotics, and suppressive therapies can be given (see treatment of Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more ). Infliximab is effective in closing anal fistulas caused by Crohn disease Fistulas Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more .
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Society of Colon and Rectal Surgeons: Clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula