The changing urodynamic pattern from infancy to adolescence in boys with posterior urethral valves

Objective To determine whether bladder dysfunction in boys with posterior urethral valves (PUV) changes from a uniform pattern of hypercontractility during infancy to the hypocontractility found in adolescence, by reviewing serial urodynamic studies. Patients and methods Thirty boys with PUV and no voiding symptoms underwent a total of 86 urodynamic tests (mean 2.8 each). The first urodynamic study was undertaken at 1-4 years of age in 15 boys and at 5-13 years in 15. They were re-evaluated at least 3 years later; 15 patients underwent the first and last urodynamic study, respectively, at a mean age of 2.8 and 7.7 years (group A), 10 boys at 6.2 and 8.5 years (group B) and five at 9.4 and 15.2 years (group C). In 10 boys aged >5 years the first and last pressure-flow studies (PFS) were analysed using an advanced analysis (PFA) to better identify hypocontractility. Results Bladder dysfunction was found in 21 of 30 (70%) boys at the first evaluation and in 18 (60%) at the last. In 25 boys the urodynamic pattern changed. Of the 15 boys in group A, 10 of 12 who had hypercontractility changed to normal (seven), low compliance (one) or hypocontractility (two), and two remained stable; two of the remaining three with normal urodynamic studies changed to hypocontractility, while one was unchanged. Among the 10 boys in group B, six with hypercontractility changed hypocontractility (three); to normal (three) or hypocontractility (three); two with normal urodynamic findings and one with low compliance changed to hypocontractility. Of the five boys in group C who showed severe hypocontractility after puberty, three had a normal pattern, one low compliance and one hypercontractility before puberty. The PFA showed a 'weak' detrusor in four of the seven boys who were considered normal on standard PFS. At the urodynamic follow-up, the PFA pattern changed to a 'weak' detrusor in four boys who had a normal (two) or strong (two) detrusor at the first evaluation. Conclusions Bladder dysfunstion in boys with PUV changes during childhood and through adolescence. The urodynamic pattern of hypercontractility generally found soon after valve ablation gradually changes to hypocontractility in many boys and this pattern seems to be the rule after puberty. The evidence from this series supports the hypothesis that long-term detrusor hyperactivity in boys with PUV leads to detrusor failure, but a longitudinal 15-year follow-up from birth to puberty is needed to validate this concept.