Urodynamic dysfunction in infants with vesicoureteral reflux

Patients and Methods: Vesicoureteral reflux (VUR) may result from inadequate length of the intravesical ureter ic tunnel and from urodynamic dysfunction. VUR and symptomatic urinary tract infection (UTI) are both more common in male infants and may be related to urodynamic dysfunction and functional intravesical obstruction. We therefore conducted urodynamic studies in 75 infants with primary VUR and retrospectively evaluated their voiding cystourethrogram (VCUG) for evidence of inadequate sphincteric relaxation. Results: High voiding detrusor pressure (>70 cm H2O), increased postvoid residual (>2 mL/kg body weight), or detrusor-sphincter dyssynergy were observed in 79% of infants with primary VUR without significant differences between male and female infants or in infants with or without UTI, Infants with bilateral grade IV-V VUR showed a higher prevalence of detrusor hyper-reflexia and higher voiding detrusor pressure than infants with lower grades of VUR or unilateral grade IV-V VUR. On VCUG, inadequate external urethral sphincter relaxation during voiding was noted in 10 of 47 male infants. Conclusions: The findings suggest that high intravesical pressures contribute to the development and severity of VUR, and that high voiding detrusor pressure in some infants with primary VUR may be related to inadequate relaxation of the external urethral sphincter.