When can persistent hydroureteronephrosis in posterior urethral valve disease be considered residual stretching?

Persistent hydroureteronephrosis (HUN) is often seen in boys with a history of a posterior urethral valve even years after valve ablation and it is often assumed to represent residual stretching. We determined the association of HUN with urodynamic abnormalities, the effect on HUN of treating these abnormalities and when persistent HUN could be considered residual stretching.

Of 71 patients with a posterior urethral valve evaluated after valve ablation 20 (28.2%) had persistent HUN in a total of 32 renal units (RUs). The degree of HUN was graded as mild, moderate or severe. Videourodynamics were performed in all patients with persistent HUN and abnormal urodynamic findings were aggressively treated. HUN was then reassessed and categorized as resolved, improved or unchanged.

Abnormal urodynamic findings, primarily hypocompliance and instability, were noted in all 20 patients with HUN. All patients compliant with treatment showed dramatic improvement or complete resolution of abnormal urodynamic parameters. The 32 RUs with persistent HUN were initially graded as mild (8), moderate (13) and severe (11). HUN resolved in 15 RUs and improved to a lower grade in 11 in 26 of the 27 RUs (96.3%) in the 17 patients compliant with treatment. The 3 boys (5 RUs) who were noncompliant with treatment had neither decreased HUN nor improved urodynamic parameters. The 12 of 27 RUs (44.4%) in the treatment group in which HUN failed to resolve completely had no distal ureteral obstruction or identifiable persistent urodynamic abnormality and, thus, they can be labeled as having residual stretching.

Persistent HUN following valve ablation should not be considered residual dilatation until a thorough urodynamic evaluation has been done and any abnormal parameters are addressed. With correction of these abnormal parameters one can expect significant lessening of HUN and hopefully improved long-term preservation of renal function.