Clinical Presentation

Fistula-In-Ano

Outcomes

Treatment

Clinical Presentation

There is an overwhelming male preponderance in perianal abscess. The majority occur in children less than 2 years old (usually before the age of 6 months) with a high incidence of fistula formation. Parents frequently report the presence of a perianal mass and sitting intolerance. Examination of the anus reveals a tender, erythematous mass lateral to the anus. Perirectal abscesses are frequently associated with fever and malaise in addition to sitting intolerance.

Careful digital examination can detect even deep perirectal abscesses as a fluctuant mass. Crohn's disease may present as a perirectal abscess and must be considered. Rarely, infected rectal duplications or dermoid cysts can present clinically as perirectal abscesses. Type III saccrococcygeal teratomas have been mistakenly identified and treated as perirectal abscesses. CT scan of the abdomen and pelvis with oral, rectal and IV contrast will identify most perirectal abscesses not found on physical examination.

The traditional management of perianal abscess is incision and drainage. This is associated with a significant recurrence rate. Conservative management includes sitz baths. Antibiotics are typically not required. Deeper infections require immediate drainage under general anesthesia with concurrent intravenous antibiotics. Because of the high incidence of associated fistula with perianal abscess, treatment includes a search for a coexisting fistula and subsequent treatment by fistulotomy.

One-third of superficial perianal abscesses resolve with conservative management; the remainder require surgical drainage. One-third of abscesses recur. Deeper infections heal well after incision and drainage. As with the superficial lesions, recurrence is not uncommon.

Nearly 30-50% of infants presenting with perianal abscesses actually have fistula-in-ano. Although crypt abscesses are the usual cause of a fistula-in-ano, perianal abscesses may be the inciting infection. In patients with perianal abscesses, up to 50% will develop a fistula.

Again, the history and physical examination are adequate to make the diagnosis. Children with fistula-in-ano have pain with bowel movements and frequently have recurrent perianal infections that drain mucus. Once the mucus stops draining, a small, indurated pustule will become evident. Occasionally dark stool may be seen inside the tract.

Image 7.12 A classification of fistula-in-ano according to Parks et al. (1976).

Classically, the cause of fistula-in-ano is a crypt abscess that extends to the perianal skin. The fistula tract is usually intersphincteric (tracking between the internal and external sphincters) or transsphincteric (penetrating through the external sphincter muscle tissue) connecting the crypt to the external perianal skin (Image 7.12). In infants, the fistula almost always extends straight radially from the involved crypt and opens on the skin laterally. Goodsall's rule (relates the external opening of an anal fistula to its internal opening) does not apply in infants.

Дата добавления: 2014-10-15