DETRUSOR HYPOCONTRACTILITY IN CHILDREN WITH POSTERIOR URETHRAL VALVESARISES BEFORE PUBERTY

Objectives To assess prepubertal boys with posterior urethral valves ( PUV) using an analysis of pressure-flow studies to evaluate the voidin g phase and thus determine if myogenic failure (hypocontractility) ari ses before puberty and if it can be detected early. Patients and metho ds Eleven boys (8-13 years old) with PUV underwent urodynamics and the results were analysed using pressure-flow mathematical analysis (PFA) of the following variables of detrusor activity: contraction velocity (V-det), detrusor contractile power expressed as power factor (MIF) a nd Schafer's diagram, which differentiates a 'strong','normal' and 'we ak' detrusor. V-det and WF were compared with normal values previously determined in boys of similar age and considered 'low' if more than 2 SDs below the mean. The results of PFA were compared with standard pr essure-flow studies and the three classical urodynamic patterns in boy s with PUV, as determined by voiding symptoms. The subsequent PFA of s even of the 11 boys were also assessed as they had undergone previous urodynamics when <8 years old. Results As assessed by the three patter ns of dysfunction, two boys had bladder instability, two had low compl iance and three had hypocontractility, with four boys being normal. Fr om the PFA, the V-det and WF were lower than normal, respectively, in seven and nine of the 11 boys; Schafer's nomogram showed a 'weak' detr usor in seven boys. The PFA suggested a pathology in four of five boys with symptoms and in three of six with no symptoms (two of the six sh owing a 'low' WF). Moreover, in older (11-13 years) boys, all five had a 'weak' detrusor, a 'low' WF and four a 'low' V-det. Of the seven pa tients who underwent repeat PFA, three had a stable WF 3 years later, one (normal) worsened slightly and two were clearly worse, while one, who underwent late (at 3 years old) valve ablation, had an increased W F, Conclusions The PFA showed hypocontractility in two-thirds of prepu bertal boys with PUV, including asymptomatic patients. These findings confirm the hypothesis that bladder dysfunction in boys with PUV event ually causes detrusor myogenic failure and finally a postpubertal over distended bladder.