Advancement Flaps

Steven R Brown, Consultant Colorectal Surgeon

Powerpoint File

Although the majority of anorectal fistulae may be treated with laying open of the fistulous tract (fistulotomy) patients with higher lying fistulae or women with anterior fistulae where fistulotomy may threaten continence present a management dilemma. Preservation of the sphincters by 'core out' of the tract (fistulectomy), closure of the internal opening and protection of the repair from the faecal stream and the high intraluminal pressures of defaecation by means of an advancement flap may provide a solution for these more complex fistulae.

From the first description of this procedure over 100 years ago, most would agree that the important components of the procedure include excison of the internal opening, excision or curettage of the primary tract, formation of the flap and drainage or closure of the external opening. Variations are usually in the construction of the flap and include mobilisation of different thicknesses of rectal wall (mucosa only, partial and full thickness rectum) caudad. Critics of this rectal advancement technique have suggested a significant incidence of incontinence (partially related to division of a portion, if not all, of the internal sphincter and partially related to the dilation of the anal canal required to obtain adequate surgical access) and problems with ectropion. An anocutaneous flap (V-Y, Y-V, house or diamond) is advocated as a way of avoiding such problems.

Whatever the technique the success is difficult to gauge. Although almost universally excellent in the literature for all techniques (including simple closure!) , it is difficult to compare results due to the varied complexity of the fistulae treated and the follow up period. There may also be an element of publication bias. Basic principles include sorting out sepsis before attempting a flap and repeating the procedure if there has been a previous failure. Although the chances of success for repeat procedures may be reduced, there are still significant healing rates.

Patients with high fistulae associated with Crohn's disease present an even more complex challenge. Advancements flaps have been described as potential therapies, albeit with less success that non-inflammatory fistulae. Diseased rectal mucosa in some of these cases necessitates an ano-cutaneous approach. Rectovaginal and pouch vaginal fistulae are other challenging management dilemmas occasionally requiring more novel approaches to flap construction. The utilisation of techniques such as labial fat pad transposition (Martius graft) and gracilis interposition are described.

Recommended reading

Anal fistula. Surgical evaluation and management. Eds Phillips RK, Lunniss PJ. Chapman & Hall Medical.