Renal transplantation in children with abnormal lower urinary tract.

OBJECTIVE: This retrospective study reports the outcomes as well as pre- and posttransplant urologic treatments of renal transplantation for children with an abnormal lower urinary tract (LUT). METHODS: Between March 1981 and December 2001, 195 children (< or =18 years of age) received live-donor kidney transplants. The 15 recipients (14 boys and 1 girl, mean age 13.5 +/- 3 years) who had lower urinary tract disorders included posterior urethral valves (PUV) with valve bladder (n=12) and neuropathic bladders secondary to meningomyelocele (n=3). These children were evaluated by voiding cystourethrogram, cystourethroscopy, and cystometry. The children with PUV were maintained on clean intermittent catheterization (CIC) and a detrusor relaxant at least 3 months before transplantation. Augmentation ileocystoplasty or continent cutaneous diversion were used in three patients. The graft and patient survivals as well as complications in this cohort was compared with a group of children with normal LUT, who underwent renal transplantation during the same period. RESULTS: One child died in the early posttransplant period due to rupture of the external iliac artery. Follow-up ranged from 6 months to 16 years (mean=4.5 years). During the same period the graft and patient survival rates were comparable between the group of children with versus without abnormal LUT. Furthermore, mean serum creatinine and creatinine clearance values were also comparable. The group with an abnormal LUT showed a higher incidence of urinary fistula (3/14) and recurrent UTI and/or bacteremia (4/14). CONCLUSIONS: Renal transplantation is feasible with good results for children with abnormal LUT. Pre- and posttransplant urologic management is critical for a successful outcome. However these children display a high incidence of urologic and infectious complications.

Bladder substitutes controlled by the anal sphincter: a comparison of the different absorption potentials.

A comparative study of the absorption potentials of the simple rectal bladder (10 patients), modified rectal bladder (20) and ureterosigmoidostomy (10) was done with intrarectal instillation of 22sodium. Results indicate that absorption is significantly greater among patients with ureterosigmoidostomy. The emptying patterns of ureterosigmoidostomy and the modified rectal bladder were also studied by ascending scintigraphy with 99mtechnetium. Evidence was provided that in cases with ureterosigmoidostomy the isotope is distributed throughout the entire colon. These studies proved the role of the colorectal valve in preventing reflux of urine from the rectum to the proximal colon. Consequently, the surface area of colonic mucosa exposed to urine is decreased and the rate of reabsorption is limited.

Evolution of the rectal bladder as a method for urinary diversion.

A critical analysis of previous reports reveals 2 main drawbacks of the rectal bladder: 1) recurrent pyelonephritis with subsequent loss of renal function (30 per cent) and 2) nocturnal urinary leakage (40 per cent). In a randomized prospective study the role of a submucosal tunnel for prevention of reflux was evaluated. We demonstrated objectively that this technique could provide a patent unidirectional flow of urine in the majority of cases (82.5 per cent). Urodynamic measurements, including flowmetry, rectal pressure and anal electromyography activities, indicated that the driving force for voiding is the voluntary increase of the intra-abdominal pressure rather than the intrinsic contractions of the smooth muscles of the rectum. Accordingly, attempts at control of nocturnal urinary leakage were directed towards increasing the resistance offered by the pelvic floor. The efficiency of imipramine hydrochloride to achieve this goal was tested against a placebo in a clinical trial performed in a prospective randomized fashion. This treatment was effective in the control of enuresis in a significant number of patients (75 per cent). We conclude that the rectal bladder with a terminal colostomy is a highly recommended method for permanent urinary diversion when these 2 modifications are used.