The changing urodynamic pattern in valve bladders during infancy.

Bladder dysfunction in boys with posterior urethral valves is well documented in studies of long-term followup. These reports suggest that dysfunctional bladders can be divided into 3 main types, including unstable, low compliant and over distended. To our knowledge urodynamic findings at presentation during infancy have not been described previously. We report on 16 male patients born between 1989 and 1993 who presented with symptoms of posterior urethral valves between birth and age 5 months, and who were followed with repeated urodynamic evaluations for a mean of 19 months. At presentation the bladder was hypercontractile with low capacity. During the first 3 years of life, the urodynamic pattern changed with vanishing hypercontractility and increasing bladder capacity, although instability remained unchanged with emptying difficulties. Thus, the 3 patterns of bladder dysfunction reported in older boys after resection of posterior urethral valves could not be found in infants and small children.