The Mitrofanoff principle is based on implantation of a supple tube within a submucosal tunnel with firm muscular backing. Reservoir pressure during filling coapts the catheterizable channel to prevent leakage and provide continence. Although this principle has been applied most commonly for procedures in the appendix, other substitutes have included transversely tubularized bowel segments (Yang-Monti), ureteral remnants, or even müllerian structures. Careful patient selection is critical in that these channels have a high rate of continence, and failure to catheterize regularly may cause infection, hydronephrosis, or reservoir perforation.
The patient will require a formal bowel preparation, appropriate preoperative antibiotic coverage, and a latex-free environment when indicated. A balloon catheter is placed transurethrally.
Make a lower midline or transverse incision (Pfannenstiel) ( Fig. 56.1 ). Develop the prevesical space and mobilize the right colon along the white line of Toldt to gain adequate mobilization of the appendix and mesoappendix.
Remove the appendix with a cuff of cecum to provide length and a wider stoma to help minimize stenosis at the skin level. Close the cecum in two layers with 3-0 self-absorbable suture (SAS) in a similar fashion as for an open appendectomy. Preserve the appendiceal artery at all times; however, the mesoappendix should be mobilized until the desired stomal location can be reached without tension ( Fig. 56.2 ).
An alternative to a short appendix is to incorporate some tubularized cecal wall with the appendix. This can be done in a uniform fashion using a stapler ( Fig. 56.3 ), which is a useful maneuver in obese patients. Care should be taken not to injure the blood supply.
Typically, the appendix is tunneled into the bladder into a posterolateral position ( Fig. 56.4 ). However, the ultimate location should be determined by appendiceal length, stoma location, and mobility of the bladder. Open the bladder in a clamshell configuration. Alternatively, if the stomal location is to be the umbilicus, a superiorly based U -shaped bladder flap can be used that is similar to a Boari flap (see Chapter 34 ).