Urodynamic pattern in asymptomatic infants: Siblings of children with vesicoureteral reflux

Purpose: We studied the urodynamic pattern in asymptomatic infants who are siblings of children with vesicoureteral reflux. Materials and Methods: Cystometry and perineal electromyography were perfor med with voiding cystourethrography in 16 male and 21 female infant sibling s screened for reflux at age 0.2 to 7.3 months (median 1.1). Results: Vesicoureteral reflux was present in 25% of the male and 10% of th e female infants. In those without vesicoureteral reflux unstable bladder c ontractions were noted in 8% of the male and 16% of the female subjects. In these infants median maximum voiding detrusor pressure was 127 (range 84 t o 211) and 72 cm. water (range 42 to 240), respectively, and median bladder capacity was 20 mi. (range 10 to 49 and 10 to 120, respectively). Maximum voiding detrusor pressure was significantly higher in male than in female i nfants (p <0.01). Perineal electromyography was interpretable in 13 of the 16 male and 16 of the 21 female infants overall. All but 1 female subject h ad increased activity during voiding, which was also present intermittently in all subjects. Conclusions: Our study of asymptomatic siblings of children with vesicouret eral reflux has provided results that may be used as reference data for nor mal urodynamics in early infancy. Instability was rare. Bladder capacity wa s lower than expected with a predicted capacity at birth of approximately 2 0 mi. Maximum voiding pressure was high, especially in male subjects. The u rodynamic voiding pattern suggests physiological dyscoordination, probably due to immature detrusor-sphincter function.