Objectives: To determine the late complications and consequences for renal function, vitamin and acid-base metabolism after application of the Mainz Pouch I (MZP-I) technique in children and young adults.
Patients and methods: To November 1994, the MZP-I procedure was carried out in 463 patients at our institution, 91 of whom were children and adolescents (< or = 20 years old) using bladder augmentation in 21 and a continent cutaneous stoma in 70. A minimum follow-up of 1 year was possible in 87 patients or 163 renal units (RUs) with a mean of 5.5 years (range 1-10.5).
Results: At the last examination, 23 of 55 (42%) preoperatively dilated RUs had improved. 131 of the 163 RUs (80%) were stable and nine RUs (5.5%) showed a slight clinical asymptomatic increase in the upper tract dilatation. Through an extraperitoneal flank incision, 11% of the RUs which developed stenosis at the ureterocolic anastomosis were successfully reimplanted (16% in patients with neurogenic disorders, 17% with pre-operative irradiation and 5% in the remaining patients). Two of 32 patients with an intussuscepted and invaginated ileal nipple required re-operation due to incontinence, but none of the patients with an appendiceal stoma were incontinent. Open revision of a stomal stenosis was performed in three and endoscopic treatment in nine patients. In 54 patients, the levels of vitamins A, B1, B2, B6, E, folic and bile acid were within normal ranges. There was no significant decrease in vitamin B12 levels after operation. In none of the patients with normal pre-operative creatinine values had the levels increased and none developed severe acidosis or bowel neoplasm.
Conclusion: The MZP-I is recommended as a technique for bladder augmentation or continent urinary diversion in children and young adults, with an acceptable complication rate which offers long-term protection of the upper urinary tract.