Conversion from colonic conduit into recto-sigmoid pouch (Mainz pouch II)

To report our long-term results of conversion from conduit conversion into a continent anal urinary diversion, as after conduit urinary diversion in childhood, some patients wish to have a later conversion to a continent diversion to avoid external appliances and to improve their quality of life.

Between 1992 and 2003, 139 patients had a urinary diversion with a recto-sigmoid pouch (Mainz pouch II), of whom four had a conversion from a colonic conduit diversion to a recto-sigmoid pouch. The mean (range) age at conduit diversion was 5.5 (3-14) years and the mean interval between conduit diversion and conversion to a continent anal diversion was 8 (4-18) years. The mean age at conversion into a Mainz pouch II was 13 (8-32) years and the follow-up afterward was 11.5 (1-13) years. The conversion was done by incorporating the pre-existing colonic conduit into the recto-sigmoid pouch with no ureteric reimplantation.

There were no early complications; one nephrectomy was required 5 years after conversion because of uretero-intestinal obstruction and pyelonephritis. All other reno-ureteric units remained stable and renal function was maintained. All patients are continent day and night; three require substitution with alkali at a base excess of < -2.5 mmol/L to prevent hyperchloraemia and acidosis.

The recto-sigmoid pouch is a therapeutic option when patients desire conversion from an incontinent type of urinary diversion to a continent type.