Rectosigmoid pouch (Mainz Pouch II) in children.

Area of Science:

• Pediatric Urology
• Surgical Reconstruction
• Genitourinary Anomalies

Background:

• Continent anal urinary diversion is a critical therapeutic option for bladder exstrophy.
• The rectosigmoid pouch (Mainz pouch II) is a modification of ureterosigmoidostomy, aiming for improved outcomes.

Purpose of the Study:

• To evaluate the long-term results of the Mainz pouch II procedure in children with genitourinary anomalies.
• To assess continence, renal function, and metabolic changes following the Mainz pouch II procedure.

Main Methods:

• A cohort of 38 children underwent the Mainz pouch II procedure between 1991 and 2004.
• Follow-up included renal function tests, continence assessment, metabolic monitoring, and rectosigmoidoscopy.
• Mean follow-up duration was 112 months for 35 children.

Main Results:

• Excellent daytime continence was achieved in all patients; 8.6% experienced nighttime incontinence.
• 15.8% developed pyelonephritis, primarily due to ureterointestinal anastomosis stenosis or reflux, necessitating reimplantation in 14.5% of renal units.
• Serum creatinine remained normal; 69% required alkali supplementation to prevent metabolic acidosis.

Conclusions:

• The Mainz pouch II procedure demonstrates high continence rates and long-term safety for children with genitourinary anomalies.
• Regular monitoring of the upper urinary tract and acid-base balance is essential.
• Annual endoscopy is recommended from postoperative year 10 due to malignancy risk at the ureterointestinal anastomosis.