The suprasphincteric fi stula originates, as usual, in the mid-anal canal in the intersphincteric space, where its internal opening can generally be found. The fi stula extends upward in the intersphincteric plane above the puborectalis muscle into the supra­levator space, where it often causes a supralevator abscess. The fi stula then penetrates the levator dia­phragm and continues downward in the ischiorectal space to its external orifi ce in the perineal skin (Fig. 20–4). This type of supralevator infection must not be drained through an incision in the rectum. Parks and Stitz (1958) recommended an internal sphincter­otomy from the internal opening of the fi stula distally and excision of the abscess in the intersphincteric space, if present. They then divide the lower 30–50% of the external sphincter muscle and continue this incision laterally until the lower portion of the fi stu­lous track has been opened down to its external opening in the skin. This maneuver leaves the upper half of the external and internal sphincter muscles and the puborectalis muscle intact. Insert a seton of heavy braided nylon through the fi stula as it sur­rounds the muscles. Tie the seton with fi ve or six knots but keep the loop in the seton loose enough so it does not constrict the remaining muscles at this time. Insert a drain into the supralevator abscess, preferably in the intersphincteric space between the seton and the remaining internal sphincter muscle. Once adequate drainage has been established, remove this drain, as the heavy seton prevents the lower portion of the wound from closing prema­turely. Parks does not remove these setons for at least 3 months. It is often necessary to return the patient to the operating room 10–14 days following the initial operation to examine the situation care­fully and to ascertain that no residual pocket of infec­tion has remained undrained. Examination under anesthesia may be necessary on several occasions before complete healing has been achieved. In most cases, after 3 months or more has passed the supra­levator infection has healed completely, and it is not necessary to divide the muscles enclosed in the seton. In these cases simply remove the seton and permit the wound to heal spontaneously. If after 3–4 months there is lingering infection in the upper reaches of the wound, it is possible to divide the muscles contained in the seton because the long­standing fi brosis prevents signifi cant retraction and the muscle generally heals with restoration of fecal continence.

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