Rectosigmoid Pouch (Mainz Pouch II) in Children

Abstract

Continent anal urinary diversion is a therapeutic option in bladder exstrophy. We report our long-term results with the rectosigmoid pouch (Mainz pouch II), a modification of the classic ureterosigmoidostomy. A total of 38 children with a mean age of 5 years (range 0.5 to 17) underwent a Mainz pouch II procedure between 1991 and 2004. Most patients (33) had bladder exstrophy or incontinent epispadias. In 14 children (37%) urinary diversion was performed after failed primary reconstruction. In 6 children conversion was performed from an incontinent type of urinary diversion. Renal function, continence and metabolic changes were analyzed. A total of 35 children were followed for a mean of 112 months (range 5 to 147). All children were continent during the daytime but 3 (8.6%) suffered from nighttime incontinence requiring pads. With respect to the upper urinary tract, 6 children (15.8%) had development of pyelonephritis, mostly with stenosis of the ureterointestinal anastomosis. Reimplantation of the ureter was required in 10 of 69 RU (14.5%), of which 7 (10.1%) were due to ureterointestinal stenosis and 3 (4.3%) were due to reflux. Serum creatinine was within normal limits in all children. During followup acid-base balance was monitored, and early alkali supplementation was initiated in 24 of 35 children (69%) when the base excess was less than -2.5 mmol/l. One child had development of clinical acidosis requiring hospitalization. After followup of more than 10 years annual rectosigmoidoscopy was performed in 16 children/young adults without pathological findings. The Mainz pouch II procedure for children with genitourinary anomalies promises excellent continence rates. However, periodic followup studies are important to check the upper urinary tract and prevent metabolic acidosis. Due to the risk of malignancy at the ureterointestinal anastomosis, endoscopy should be performed annually beginning at postoperative year 10. The Mainz pouch II procedure is safe in the long term. Without stoma, appliance or catheterization this type of continent urinary diversion is specifically suitable for children.