Royal Prince Alfred Hospital
Royal Prince Alfred Hospital
Department of Colorectal Surgery

Colorectal Surgery

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Mucosal advancement flap

A mucosal advancement flap (MAF) is a treatment for anal fistulas that are not suitable for a fistulotomy due to the amount of anal muscle below the fistula. The procedure helps to treat fistolotomy while conserving anal muscle function to help avoid anal or faecal incontinence.

In this procedure a flap of the inner lining of the bowel wall known as mucosa and the layer under the mucosa is developed so that the internal fistula opening can be closed with sutures and covered by the flap, but closed in such a way that the edges of the stitched flap are away from the internal opening and effectively the internal opening and cause for the fistula in the first place has been obliterated.

Depending on the type of fistula success rates of between 50 and 70% for are reported. This is why there are many procedures for complex fistula involving more than about 30 to 50% of the anal muscle below, anterior (vagina side) fistula in females, and those with multiple tracts and those associated with Crohn's disease.

A drain is commonly placed in the excluded fistula tract during surgery, and is removed later. Following surgery there are risks of bleeding and infection, and longer term risks of a mucous leakage from the anus, and the risk of fistula recurrence, but it is best to discuss these with your doctor for more specific details related to your fistula and your planned surgery.

 

Reviewed 2017