Simple fistulas may be approached through the vagina, perineum, or rectum. Vaginal approaches are most often used by gynecologists and include the inversion technique and the layered closure. With the patient in the lithotomy position, the inversion technique involves exposure of the fistula by pressure on the rectal side. The vaginal mucosa is incised circumferentially around the fistula. A purses-tring suture is placed in the fistula tract and the needle is passed to the rectal side. Tying of the suture at this point inverts the fistula to the rectal side. Muscle layers and the vaginal mucosa are reapproximated over the repair. The layered closure is the more common vaginal approach and involves a longitudinal elliptical incision around the fistula. A mediolateral episiotomy may be performed for better exposure. The vaginal mucosa is circumferentially dissected for 2 to 3 cm and the fistulous tract excised. The rectal mucosa is closed followed by reapproximation of the rectal muscle, rectovaginal septum, and vaginal mucosa in separate layers. The success rate for both is 84% to 100% and complications include bleeding, hematomas, cellulitis, urinary retention, and fistula at the episiotomy site.6
Perineal approaches include fistulotomy, cutting setons, conversion to perineal laceration with layered closure, and sphincteroplasty. The use of fistulotomy and cutting setons is mentioned only to be condemned because of the high risk of postoperative incontinence from sphincter damage. Conversion of the fistula to a perineal laceration with layered closure is more often used although not widespread because of the inherent division of the sphincter and the unknown rate of subsequent incontinence (Figure 12-2.3). For this technique, the patient is placed in the prone position after antibiotic and mechanical bowel preparation. The bridge of skin and muscle distal to the fistula are divided and the fistula tract is excised. The rectal mucosa is closed and the levators and the external anal sphincter are mobilized and reapproximated. The perineal body is reconstructed and the vaginal mucosa closed. This technique has been evaluated in small studies and demonstrates close to a 100% success rate.6 The complications include hematoma, fever, and urinary tract infection. The disadvantage with this approach is the division of the sphincter mechanism and unknown long-term incidence of fecal incontinence.
Sphincteroplasty is considered a perineal approach to the correction of low rectovaginal fistulas, particularly those that are transsphincteric and result from obstetric trauma. The symptoms of rectovaginal fistula may mask true fecal incontinence that may manifest once the fistula is repaired. In addition, the sphincter muscle is the most vascular tissue between the rectum and vagina such that its absence diminishes success of local repair and its use in local repair predisposes to a higher success rate and functional outcome.7 Consequently, patients with either an occult or symptomatic sphincter defect are candidates for this technique. The technique of overlapping sphinctero-plasty is explained in detail in the chapter on anal sphincter repairs. Briefly, it involves placing the patient in the prone position under general anesthesia after mechanical and antibiotic bowel preparation. A curvilinear incision is made between the anus and vagina. A flap of anoderm and
rectal mucosa and submucosa is raised off the internal anal sphincter. The external and internal anal sphincters are dissected free. The levators and the internal anal sphincter are separately plicated. The external anal sphincter is divided in the midline and the ends are overlapped and sutured in place. The endorectal flap is sutured to the reconstructed sphincter. The vaginal wall is reefed and the perineal body reconstituted before closure of the wound. The success rate with this technique is 78% to 100%.6
The most popular approach and the procedure advocated at our institution is the sliding endorectal advancement flap (Figure 13-2.4). The patient undergoes mechanical and antibiotic bowel preparation and is placed in the prone position with either local or general anesthesia after placement of a urinary catheter. A rectal flap is created with a base that is twice the length of the apex to ensure vascularity. The flap is composed of mucosa, submucosa, and circular muscle and is mobilized at least 4 cm to minimize the risk of tension. The fistulous tract is curetted of granulation and unhealthy tissue. The vaginal opening is closed with interrupted Vicryl sutures. The internal anal sphincter is mobilized bilaterally and reap-proximated midline. The portion of the tract containing the fistulous opening is excised and the new edge of the flap brought distally and sutured in place using Vicryl sutures. Perioperative antibiotics are administered for 24 hours. Bulking agents are advocated to prevent trauma from stool to the repair. Tampons and sexual intercourse are prohibited for 6 weeks postoperatively. Success rates are reported between 71% to 100%.6
In knowledgeable hands,simple rectovaginal fistulas can be successfully repaired in any one of several ways. The advantage of the endorectal advancement flap is that the repair is directed at the high-pressure side of the fistula and an associated defect in the external anal sphincter can be concomitantly undertaken. In general, the advantage of the transanal and vaginal approaches is the lack of sphincter mechanism disruption, whereas perineal repairs involve transection of the sphincters and the unnecessary risk of permanent damage.
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