Fistula Plug Treatment for High (Complex) Anal Fistulae

 
An anal fistula is an abnormal tunnel with an internal (“primary”) opening in the rectum and an external (“secondary”) opening in the skin surface near the anus.  Anal fistulae typically arise from an abscess developing in glands adjacent to the anus; these abscesses sometimes form a passage connecting the anal canal to the skin.  Other conditions that predispose to fistulae include malignancy, Crohn’s disease, inflammatory bowel diseases, radiation therapy and also as a complication of surgery. 

 

Guy Nash (pictured on right) with other RSOs at St Marks (The Fistula Hospital) London

Most anal fistulae are simple low fistulae arise from peri-anal abscesses and their tracts involve 50% of the length of the internal anal sphincter and 30% or less of the external anal sphincter.  Complex fistulae are those that:  (a) involve more than 30% of the external sphincter; and/or (b) are anterior in females; and/or (c) have multiple tracks: and/or (d) are recurrent; and/or(e) arise from some other aetiology such as Crohn’s disease.  Treatment of complex fistulae can be difficult, and typically presents a higher risk of incontinence since the fistula tract enters the bowel higher (thus high fistula). The treatment goals are to clear infection but also maintain continence.  These goals can be satisfactorily reached in low fistulae [see figure] by “laying open” of the fistula, allowing for secondary healing.  Healing rates are typically over 90% but even this procedure carries a small risk of incontinence.

Many options have existed for treating high fistulae [see figure], including cutting out the tunnel (fistulectomy) with repair of the sphincter, setons, and fibrin glue injections.  Each of these options offers a trade-off between healing and maintaining a functional sphincter; those with the highest healing rates result in the highest rate of incontinence.

 

The Fistula plug is derived from porcine small intestinal submucosa (SIS).  SIS is an acellular biomaterial that has been used extensively in various applications and configurations for hernia and pelvic floor repair.  SIS allows in-growth of the body’s native tissue and, over time, becoming completely resorbed by the body.

Clinical results of anal fistula plug repairs report 30 - 80% healing rates for complex anal fistulae in both the Crohn’s and non-Crohn’s population, with no evidence of incontinence or infection.^{1, 2, 3}  The procedure is typically performed under general anesthesia as day surgery.  It is well-tolerated by patients who can return to normal daily functions other than heavy straining. In patients that whose fistulae are not successfully treated, further episodes of sepsis may occur but they are no worse off than prior to the surgery.