Randomized controlled trial of primary fistulotomy with drainage alone for perianal abscesses

Primary fistulotomy may be advantageous for perianal abscesses because unlike ischiorectal abscesses, fistulas are more commonly found and can be laid open with full preservation of the external anal sphincters. Therefore, a randomized, controlled trial was conducted to compare primary fistulotomy with incision and drainage alone, specifically for perianal abscesses.

Fifty-two consecutive patients (43 males; mean age, 40 (standard error of mean, 2) years) with perianal abscesses were randomized to treatment by either incision and drainage (controls; N = 28) or fistulotomy (N = 24). Patients were followed up clinically for a mean of 15.5 (standard error of the mean, 0.7) months. Anorectal manometry was also performed before, six weeks, and three months after surgery.

Persistent fistulas developing after surgery were significantly more common after incision and drainage (N = 7; 25 percent) than after fistulotomy (N = 0; P = 0.009). One patient in each group was also found to have a residual abscess, which required repeat drainage. All patients remained fully continent. The anal pressures after incision and drainage and fistulotomy were not significantly different. Operative time, hospital stay, and time for the wound to heal completely were the same in both groups.

Primary fistulotomy at the time of drainage for perianal abscesses results in fewer persistent fistulas and no added risk of fecal incontinence.