Urodynamic studies in prune belly syndrome. A case report.

Urodynamic studies were carried out in a 14-year-old boy with Prune Belly Syndrome and terminal renal failure prior and after successful renal transplantation. Increased bladder capacity, nonprovocative detrusor instability and a high compliance were the most characteristic findings during the filling phase of the bladder. During the voiding phase an increased detrusor pressure was demonstrated. Outflow resistance and maximum urinary flow rate were within normal range before and after transplantation. In contrast to the findings before renal transplantation, however, micturition was imbalanced after transplantation (residual urine 100 ml). Urodynamics revealed that the bulging of the posterior urethra, observed in the early voiding phase, was due to a congenital insufficiency of the posterior urethral musculature (megalourethra) and not caused by mechanical obstruction leading to urethral dilatation. It is suggested that detrusor-bladder-neck-dyssynergia is the primary cause of the imbalanced micturition and its consequences (bladder distention, reflux, urinary tract infection, hydronephrosis, pyelonephritis) in patients with Prune Belly Syndrome. The findings of a normal, respectively increased detrusor activity are in contrast to the observations of some authors, describing attenutation and absence of detrusor muscle fibres. The indications and effects of transurethral resection and internal urethrotomy, proposed by some authors, are discussed.