Posterior urethral valves after infancy–urodynamic consequences

Abstract

This study describes a subset of patients with posterior urethral valves (PUV) who presented late in childhood. The objective was to identify factors that lead to back-pressure effects on the upper tracts, which persist in spite of adequate valve ablation in some patients, and seek factors that may preserve the upper tracts despite untreated obstruction in other patients. Six children with PUV diagnosed after infancy were evaluated. The pre-operative work-up included renal biochemistry, ultrasonography, voiding cystourethrography, and uroflowmetry. Detailed urodynamic studies, including uroflowmetry and slow-fill cystometry, were performed in all cases 6 months after surgery. Adequacy of valve fulguration was confirmed by urethroscopy. Three of the six patients had normal upper tracts; in these, there was marked improvement in peak urine flow rates after fulguration and bladder pressures were normal. The other three patients had bilateral hydroureteronephrosis, and two had chronic renal failure. This group had markedly decreased functional bladder capacity with loss of compliance at low bladder volumes and significant residual urine volumes in spite of adequate valve fulguration, suggesting myogenic detrusor failure. We conclude that in patients with PUV presenting beyond the age of 5 years, upper-tract deterioration may accompany high storage pressures in the bladder. In some boys with long-standing obstruction the upper tracts may escape damage; in our series this was associated with normal bladder dynamics and appeared unrelated to the severity or duration of outflow obstruction.