Anal Sphincter Reconstruction After High Recurrent Anorectal Fistula Excision

A retrospective analysis of patients treated for recurrent posterior anorectal fistula, who previously had undergone radical excision of fistula-in-ano, was performed. Three types of surgical reconstruction were compared: fistulectomy with primary sphincteroplasty, muco-muscular advancement flap and full-thickness low rectum posterior semicircular mobilization.

Radical surgical treatment of anorectal fistulas implies removal of the tract, which ideally should be followed by complete wound healing and good anal sphincter function. A big variety of techniques to restore the anal canal after fistula excision have been developed, however, none of them demonstrates excellent results in difficult clinical situations. Treatment of high anorectal fistulas, as well as recurrent fistulas, has always been the most challenging task even for expert colorectal surgeons, considering the need to safely restore the anal sphincters after surgical trauma in the presence of severe postoperative fibrosis and inflammatory changes.

In high recurrent anorectal fistulas, fistulotomy isn't a method of choice as division of a big portion of anal sphincter muscles leads to postoperative incontinence. Muco-muscular advancement flap is an accepted technique for the treatment of high transsphincteric fistulas, showing the best efficacy in unchanged anal canal. Whereas in recurrent disease, due to severe fibrotic deformation of the anal canal, creating an advancement flap can be technically difficult and lead to a complication high rate and postoperative incontinence.

Creation and safe fixation of an endorectal advancement flap (ERAF) in the setting of postoperative fibrosis and perifistular inflammation can be technically difficult. Thus, mobilizing a full-thickness flap is preferred.

After coring out a high transsphincteric or suprasphincteric fistula, the wound from the inside of the anal canal is located close to the anorectal junction, where internal and external anal sphincter fuse with the levator ani muscles. When a full-thickness ERAF is created in this situation, first the surgeon enters the intersphincteric plane, and upward dissection brings him straight to the supralevator space.

This maneuver has much in common with mobilising the distal part of rectum as a part of intersphincteric resections or transanal mesorectal excision for rectal cancer \[35\] , \[36\] . After the upper part of the rectum has been mobilized, a surgeon from the perineal team makes a circular incision of the anal canal above the dentate line, enters the intersphincteric space and continues dissection in cranial direction following the surface of the mesorectal fascia, thus separating the lower part of mesorectum from the levator ani muscles.

Being an expert in intersphincteric resections, the leading surgeon utilized this approach in three patients after excision of a high recurrent anal fistula. Sphincteroplasty and standard ERAF creation were not possible due to severe fibrosis, so mobilizing the posterior semicircle of the rectum the same way as in intersphincteric rectal resection was deemed to be the last resort in order to close the wound. In fact, a wide well-vascularized posterior ERAF was created. The upward dissection was continued until the Waldeyer's septum was reached and divided to ensure tension-free fixation of the flap in the anal canal.

Eligibility Criteria:
Inclusion Criteria:

* recurrent posterior anorectal fistula
* previously had undergone radical excision
* contrast-enhanced MRI performed preoperatively
* colonoscopy preoperatively

Exclusion Criteria:

* Crohn's disease
* superficial fistulas
* low intersphincteric fistulas
* infections (anorectal sepsis, tuberculosis, HIV)