David J. Maron
Fistula in ano is a relatively common problem encountered by the colorectal surgeon. While cryptoglandular infection represents the most common cause, inflammatory bowel disease, anorectal trauma or obstetric injury, and mycobacterial infections may also lead to anal fistulas. Surgical management is based on the location and complexity of the fistula, the underlying disease process, and the potential for sphincteric compromise.
Fistulotomy remains the optimal treatment for patients with symptomatic low-lying fistulas involving minimum sphincter musculature. In patients with Crohn’s disease without active proctitis, fistulotomy may also be useful in low (distal) fistulas. In patients with rectovaginal fistulas, or high and complex fistulas where fistulotomy involving division of the anal sphincter would result in compromise of fecal continence, other modalities may be instituted. These procedures involve the use of cutting setons, fibrin glue, collagen fistula plugs, and endorectal advancement flaps. Use of these procedures is described elsewhere in this book.
Anal sleeve advancement is based on the same principles as an endorectal advancement flap. It involves the resection of a cylinder of the diseased portion of the anal canal, with mobilization of the distal rectum and advancement to the dentate line for anastomosis. Anal sleeve advancement was initially described by Whitehead for the treatment of hemorrhoids and subsequently by Delorme for the treatment of prolapsing rectal mucosa. In recent years, it has been used in complex anorectal fistulous disease.
Anal sleeve advancement flaps should be reserved for patients with complex anorectal or vaginal fistulas. Patients with a single internal fistulous opening or several openings in the same quadrant are probably best treated with a vertical or semilunar-type advancement flap. For patients with multiple internal openings involving more than one quadrant, patients with complex anorectal Crohn’s disease, or patients with anorectal stricture, sleeve advancement offers an alternative to proctectomy or permanent fecal diversion.
Careful patient selection is critical to success and important to reduce the risk of a nonhealing wound and worsening perianal disease. Patients with concomitant perianal sepsis need to undergo drainage of any abscess, with the judicious use of draining setons to prevent further sepsis. The author prefers to leave draining setons in place for a minimum of 3 months to allow for resolution of underlying inflammation. In patients with ongoing sepsis despite the use of draining setons, a diverting stoma may be used.
In patients with Crohn’s disease, sleeve advancement should be avoided in the setting of active proctitis. It is recommended that patients undergo an endoscopic evaluation of the colon and potentially a barium small bowel series to evaluate for Crohn’s disease elsewhere in the intestine, as optimal control of proximal Crohn’s disease may improve the success of the sleeve advancement flap. Assessment should also be made of the mobility and pliability of the rectal wall; this may require an examination under anesthesia in the operating room.
Preoperatively, the patient undergoes a standard mechanical bowel preparation. Oral antibiotics are not generally given, however the patient receives broad-spectrum intravenous antibiotics prior to incision. Either general or regional (spinal) anesthetic can be used, depending on the patient and surgeon preference. The procedure can be performed in either the lithotomy or prone jackknife position. The author prefers the prone jackknife position under general anesthesia.