Urinary tract reconstruction in children undergoing renal transplantation

Urologic Evaluation and Management of Pediatric Kidney Transplant Patients

Urologic causes of end-stage renal disease are estimated between 25% and 40% of causes. The goal of renal transplantation in chronic kidney disease patients is to provide renal replacement therapy with less morbidity, better quality of life, and improved overall survival compared with dialysis. A patient's urologic history can be a significant source of problems related to infections, recurrence of disease, and surgical complications. Many of the urologic risks are modifiable. Proper evaluation and management can mitigate the potential problems after transplantation, and these patients with complex urologic problems are seen to have similar graft function outcomes.

Outcome of renal transplantation in children with low urinary tract abnormality

INTRODUCTION

Patients with end-stage renal disease and lower urinary tract abnormality are often considered high risk for renal transplantation.

METHODS AND SUBJECTS

To examine the degree of risk, we studied patients who received renal transplants between 1985 and 2003. Forty eight patients had congenital lower urinary tract anomalies and 168 patients comprised a control group without these anomalies.

RESULTS

Mean age and distribution of sex were not significantly different between the case and the control group. Among patients with anomalies, 8% had delayed graft function; 75%, acute rejection; and 39.5%, chronic rejection. Among the controls 2.3% had delayed graft function; 59%, acute rejection; and 35%, chronic rejection. None of these differences was significant. Mean survival time was 6 years in affected patients and 7.3 years in the control group (P = .7). Among patients with anomalies the rate of graft survival in the first year after transplantation was 90%; and those in the third, fifth, and seventh years, 76%, 65%, and 40%, respectively. For the controls, the graft survivals were 88% at 1 year; 73% at 3 years; 70% at 5 years; and 49% at 7 years after transplantation.

CONCLUSION

This study showed that a history of lower urinary tract anomalies had no effect on graft function. Graft survival was not different among these patients compared with patients free of these anomalies.

A new, unique and simple method for ureteral implantation in kidney recipients with small, defunctionalized bladders

BACKGROUND

Major, almost insurmountable, deterrents exist to the use of the small capacity, defunctionalized, nonneurogenic urinary bladder in renal transplantation, namely, the technical difficulty in performing a satisfactory ureteral implantation with conventional methods and the potential secondary problems with high grade ureteral reflux and obstruction. Alternatives are less than ideal and include transplantation into a bowel-augmented urinary bladder with intermittent self-catheterization, ileal conduit urinary diversion, or avoidance of transplantation and relegating the patient to life-long dialysis.

METHODS

Eight consecutive patients (ages 13 months to 29 years) with small, defunctionalized urinary bladders underwent a new method of intravesical implantation of the transplant ureter. The mean capacity of these bladders was 18.5+/-13.1 ml (range 6 to 45 ml), with the bladders defunctionalized for a mean 81.6+/-24.3% of the patients' total lifetime. The technique involved placement of the transplant ureter into a shallow, mucosa-denuded, rectangular trough extending from a superiorly placed ureteral hiatus distally to the trigone. We hypothesized that the mucosal margins on the two lateral aspects of the rectangular trough would grow over the anterior surface of the ureter until they met the advancing mucosal edges from the contralateral side to form a natural neosubmucosal tunnel.

RESULTS

Posttransplantation cystoscopic examination demonstrated bladder mucosal regeneration and growth over the ureter, confirming the spontaneous development of a good length neosubmucosal tunnel. All patients demonstrated no evidence of ureteral reflux or ureteral obstruction, whereas an immediate prior cohort of four consecutive patients with bladder capacities < or =30 ml showed that three of four had ureteral reflux (P=0.02) and four of four developed hydronephrosis (P=0.002). All urinary bladders in the present cohort enlarged to expected normal or nearnormal capacities. Serum creatinines were stable throughout the entire follow-up period, with the exception of one patient who had rejection episodes. Two patients had urinary tract infections posttransplantation, but there were no episodes of acute pyelonephritis.

CONCLUSIONS

This novel technique for ureteral implantation successfully capitalizes on the regenerative potential of the bladder mucosa, resulting in a physiological, anatomically natural, and very effective neosubmucosal tunnel. It appears to guarantee success against both ureteral reflux and obstruction, no matter how small the urinary bladder, and offers no hindrance to enlarging the bladder to near normal capacity posttransplantation. The implantation technique is simple and safe, and its use should eliminate the reluctance to use these bladders. Moreover, this procedure offers a major incentive for the successful rehabilitation of small, defunctionalized, nonneurogenic bladders after kidney transplantation.

Kidney transplantation in patients with neurovesical dysfunction

BACKGROUND

Five renal recipients with neurovesical dysfunction (NVD) were retrospectively reviewed focusing on anatomical and urodynamic abnormalities of the lower urinary tract and their management prior to kidney transplantation.

METHODS

The underlying anomalies in these 5 patients were a posterior urethral valve (1 with an imperforate anus; n = 2), meningomyelocele (n = 2) and a congenital short urethra with an imperforate anus (n = 1). Their urinary tracts were evaluated prior to transplantation with voiding cystourethrography, urethrocystoscopy, cystometrography and electromyography of the external urethral sphincter to identify a possible focus of urinary tract infection, urine storage and voiding function.

RESULTS

All 5 patients had NVD proven by urodynamic studies or by documentation of urinary retention in the absence of mechanical outlet obstruction. Bilateral high grade vesicoureteral reflux was noted in all patients, requiring ureteroneocystostomy. Clean intermittent catheterization (CIC) was ultimately employed for bladder emptying in all patients. Two patients with poor bladder compliance underwent augmentation cystoplasty before transplantation. The Mitrofanoff procedure was used in 2 patients with structural urethral abnormalities to access the bladder for catheterization. After eradication of possible sources of infection and establishment of a low-pressure urine storage system with bladder emptying by CIC, kidney transplantation was performed. Following kidney transplantation, all of the recipients were asymptomatic for urinary tract infections using CIC. Although 1 patient lost his graft due to chronic rejection, the other 4 other patients have good renal function.

CONCLUSION

Kidney transplantation in patients with NVD can be performed provided that their urinary tract problems are properly resolved.