Urodynamics in the prune belly syndrome.

Urodynamic studies have been carried out in 10 boys with the prune belly syndrome. In spite of gross radiological changes the condition is compatible with normal voiding dynamics. Filling cystometrograms show a marked shift to the right. Pressure/flow studies may demonstrate an unbalanced voiding mechanism which can be treated by urethrotomy. Following urethrotomy urethral pressure profiles showed a significant fall, flow rates increased and residual urine volumes were reduced. Urological treatment in the prune belly syndrome should be directed at producing a bladder which empties well: a balanced voiding mechanism. Urodynamic investigations are helpful in achieving this aim. Residual urine determination and flow rates should be used in routine follow-up. Urethrotomy to lower bladder outflow resistance is advocated as one of the first steps in treating the unbalanced voiding mechanism that is often found in the prune belly syndrome.