A fistulectomy is where they cut open the fistula tract -- they lay the whole track open and let it heal from the inside out. They can do this for "low" fistulae, meaning without a lot of sphincter involvement. Cutting too much sphincter muscle with level you incontinent.
The advancement flap procedure is done on "high" fistulae because it doesn't cut sphincter muscle. It does done in the rectum around the fistula hole. They cut a horseshoe flap of tissue, fold it over the fistula hole, and sew it closed. This seals the fistula form the rectum. I think they rough up the fistula too and it heals/closes once it isn't getting drainage from the rectum.
Maybe some else knows differently?
Diagnosed with Crohn's in early 2007. Several peri-rectal abscesses and two fistulae with setons. Allergic to Remicade and Humira. Currently on 6MP, and vitamins D and B-12.