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 performed with voiding cystourethrography in 16 male and 21 female infant siblings 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 the female infants. In those without vesicoureteral reflux unstable bladder contractions 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 to 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 infants (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 had increased activity during voiding, which was also present intermittently in all subjects. Conclusions: Our study of asymptomatic siblings of children with vesicoureteral reflux has provided results that may be used as reference data for normal urodynamics in early infancy. Instability was rare. Bladder capacity was lower than expected with a predicted capacity at birth of approximately 20 mi. Maximum voiding pressure was high, especially in male subjects. The urodynamic voiding pattern suggests physiological dyscoordination, probably due to immature detrusor-sphincter function.