Ileocolic Continent Urostomy (Miami Pouch)

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Ileocolic Continent Urostomy
(Miami Pouch)

Continent urostomy of the ileal or ileocolic variety (Miami pouch) has become an essential part of urinary diversion in oncology patients. The mechanical engineering phenomenon of a pouch that has pressure lower than the ureteral pressure entering it and pressure lower than the efferent bowel limb leaving it, has the advantage of having no urinary reflux. That, in turn, should reduce the incidence of chronic subclinical pyelonephritis among these patients, and consequently, reduce the loss of upper renal units. The continent efferent system allows a better quality of life for a patient and avoids the social disadvantages of a urinary ostomy bag.

Physiologic Changes. The continent urostomy should be a low pressure pouch with pressures in the range of 30 cm of water. At the same time, there should be a nonrefluxing ureteral anastomosis into the pouch. If the normal ureter has pressures of approximately 60 cm of water, there should be little reflux from the pouch to the kidney. The combination of these pressure differentials should allow the patient to be continent and have little or no urinary reflux to the kidney.

Removal of a large portion of the right colon, a significant portion of the transverse colon, and a portion of the terminal ileum can cause various physiologic phenomena in the gastrointestinal tract. Removal of the right colon and some of the transverse colon may produce a watery diarrheal stool. Removal of the terminal ileum results in problems with bowel salt metabolism, and absorption of fat-soluble vitamins and vitamin B12. Loss of the ileocecal valve may involve reflux of contaminated stool back into the proximal ileum, which, in turn, can lead to problems with chronic small bowel infection and various metabolite changes.

Points of Caution. The blood supply to the Miami pouch is dependent on the ileocolic artery, particularly the right colic branch of the ileocolic artery, and the middle colic artery. These arteries connect with the marginal artery of the colon. Extreme care must be exercised so that the ileocolic or middle colic artery is not compromised. When performing the anastomosis, the surgeon must be careful to place the ureter into the colonic pouch. The ureter must prolapse 3 cm into the pouch to reduce urinary reflux. We have changed the point of exteriorization of the efferent limb onto the abdominal wall from the right lower quadrant to the umbilicus. This gives a better cosmetic effect and also reduces incontinence of the efferent bowel limb.

Technique

An outline of the colon and the small bowel is shown with the key anatomical points: the ileocolic artery, the superior mesenteric artery, the avascular plane of Treves between the superior mesenteric artery and the ileocolic artery, the terminal ileum, and the right and transverse colon. The line of Toldt is outlined in the pericolic gutter (dotted line). The dotted line shows the incisions to be made to create the pouch. In these cases, the larger portion of transverse colon is used to create a larger pouch. In radiated bowel, a large pouch will have a lower pouch pressure because irradiated bowel lacks compliance and, therefore, larger volumes of urine create excessive pouch pressure.

The midileum is anastomosed to the transverse colon in a functional end-to-end anastomosis using the stapler.

The transverse colon is brought along the side of the right colon and sutured with several interrupted 3-0 synthetic absorbable sutures. The colon is then opened in the midline with the cautery.

After opening the colon down to the cecum, the surgeon sutures the posterior wall of the pouch with interrupted 3-0 synthetic absorbable sutures.

The posterior wall of the colon can be either sutured or stapled. It is faster and easier to staple it with a TA-55 Polysorb staple using multiple bites and suturing in between each application of the stapler.

The right and left ureters have been mobilized and are brought through the posterior wall of the pouch via Leadbetter anastomotic technique. The ureters must prolapse 3 cm inside the colon after being anastomosed to allow protection from urinary reflux. Finney double-J Silastic catheters are inserted up the ureters into the kidney and brought out into the pouch.

The Leadbetter anastomosis is demonstrated by a mucosa-to-mucosa anastomosis after spatulating the ureter to prevent iris contracture postoperatively.

The pouch is folded over on itself, point A is brought alongside point A', and point B is brought alongside point B'. The segment of terminal ileum that will eventually become the efferent bowel limb is shown.

The ureters have been anastomosed to the pouch. The TA-55 polysorb stapler is used to close the margins of the pouch.

The ureters have been implanted. The margins of the pouch have been stapled with a polysorb stapler. Small areas that are awkward for the stapler to anastomose can be sutured with 3-0 synthetic absorbable suture.

Attention is turned to the efferent bowel limb. A No. 14 French catheter is inserted down the terminal ileum into the pouch. Two parallel pursestring sutures 1 cm apart are placed at the ileocecal junction with delayed synthetic absorbable suture.

The pursestring sutures have been placed. The No. 14 French catheter is seen traversing the efferent bowel limb into the pouch.

The GIA stapler with 4.8 staples is used to taper the terminal ileum on its antimesenteric border to narrow the lumen of the efferent bowel limb to the size of a No. 14 French catheter. This dramatically raises the pressure inside the lumen, such that the pressure in the lumen of the efferent bowel limb is more than twice the pressure in the pouch.

The efferent bowel limb has been tapered with the stapler. Excessive ileum is discarded.

The inferior rim of the umbilicus is excised enough to allow the efferent bowel limb to be pulled through the abdominal wall at that site.

The efferent bowel limb has been brought through the inferior rim of the umbilicus, and the excessive ileal length has been excised. The remaining stump is sutured with 3-0 synthetic absorbable suture.

In this transverse view of the completed Miami pouch, the ureters are implanted and prolapsed into the pouch. Finney J Silastic stents are placed in the pouch, and the efferent bowel limb has been sutured to the umbilicus. It is best to leave an indwelling Medena catheter inserted through the efferent bowel limb into the pouch for at least 2 weeks to allow complete healing of all suture lines. The pouch should be protected by a Jackson-Pratt closed suction cannula and irrigated every four hours with 30 mL of warm saline.