Treatment of anal stenosis will vary depending on the location, severity, and cause of the stenosis (Tables 13.2 and 13.3). Patients with stenosis from infectious causes or inflammatory bowel disease should undergo appropriate medical treatment for the underlying condition.

For patients with mild/moderate low stenosis, nonoperative treatment should be instituted, with stool softeners/bulking agents and dilation. Dilation is appropriate for stenoses from coloanal or ileoanal pull-through procedures, from crohn’s disease and radiation [19]. In children, dilation is routinely performed after pull-through procedures for Hirschsprung’s disease and anorectal malformations in order to prevent the development of anastomotic stenosis [20, 21].

For strictures from coloanal or ileoanal anastomoses, dilation may be successful, and should be initiated within the first several weeks after surgery, and digital dilation by the examiner may be all that is required [22].

In adults, there are few published standardized methods for dilation as there are in children [3, 20]. Several authors advocate performing the first dilation in the operating room using Hegar dilators followed by daily dilation at home [3, 19]. Success will therefore require a compliant and motivated patient. For those patients with mild stenosis from Crohn’s disease, about half will respond to dilation [19]. Shorter strictures will respond better to dilation than longer strictures [14].

For anastomotic strictures or those from stapled hemorrhoidopexy procedures that are located slightly higher, endoscopic balloon dilation can also be performed. Dilation for stricture is relatively safe, however, complications such as perforation can occur [23, 24]. Pain from repeated dilation may lead to decrease in success of treatment, especially in children [21]. Sphincter damage leading to fecal incontinence is also a concern with repeated dilations [1, 24].

Operative treatment is indicated for patients with moderate to severe stenosis, with stenosis associated with ectropion, and for those with mild stenosis who fail non-operative treatment.

A variety of operative procedures has been described for the treatment of anal stenosis. These should be tailored to the individual patient and the surgeon’s familiarity with the procedures. Preoperative workup prior to surgical repair is typically minimal as many patients will not tolerate an exam in the clinic. Adjuncts such as endoanal ultrasound or manometry, although helpful in determining the status of the sphincters, will not be tolerated by most patients. Examination under anesthesia in the operating room is the most important for preoperative planning [3, 19].

There are a several flaps that have been described in the treatment of anal stenosis (Table 13.3) which are described below. Flaps can be sliding (mucosal advancement, V-Y), island (Diamond, U, House), or rotational (S-plasty).

Mucosal Advancement flaps are best for mid- or high stenosis [19]. The procedure is performed laterally, and can be performed bilaterally if necessary. A radial incision is made through the scar and extending to the anal verge. The scar is excised, sphincterotomy performed, and a mucosal flap raised for 2–5 cm in length. The flap is then sutured to the intersphincteric groove, with a resultant small external wound [1]. Advantages of the mucosal advancement flap are minimal morbidity [25], small perianal wounds, and the ability to perform bilateral flaps if needed. Disadvantages include mucosal ectropion if the suture line is too distal and a higher rate of restenosis in treating distal severe disease [25].

Y-V anoplasty is another sliding flap which involves the use of a Y-shaped incision which is then sutured as a V [26]. See Fig. 13.1. The base of the Y incision (medial most aspect) should be shorter than the top of the Y (lateral aspect) to ensure that the flap has enough mobility to cover the entire defect. Care must be taken to raise a full thickness flap, as the blood supply is maintained from the most lateral aspect of the flap. Ischemia of the flap can occur if there is tension or if the flap is not the full thickness, with resultant dehiscence or restenosis [10, 27]. Benefits of this flap are its ease of performance, and no open wounds.

Island flaps are fully mobilized from the surrounding skin, which can allow further mobilization into the anal canal, making them useful in the treatment of higher stenoses. The blood supply to these flaps is through the subcutaneous tissue and allows for full mobilization and a tension-free anastomosis [28–30]. The diamond flap as described by Caplin and Kodner [4] begins with release of the scar via a lateral incision, and internal sphincterotomy can be performed if needed. This results in a diamond-shaped defect (Fig. 13.2). The flap is then drawn laterally to the incision, with the half of the flap closest to the anus being the size of the previously made incision. The full thickness flap is then created, with care taken to avoid undermining the flap, which can result in ischemia. The flap is then sutured into place and all the defects closed. This flap can also be performed bilaterally if necessary, and can be performed after failed Y-V.