Videourodynamic findings in young infants with severe primary reflux

We investigated bladder function on videourodynamic studies in infants with severe primary vesicoureteral reflux (VUR) and analyzed the relationship between VUR and intravesical detrusor pressure during the micturition cycle.

From 1999 to 2001, 3 female and 9 male infants with a median age of 9 months with VUR underwent conventional filling videourodynamics at our institution. Four cases were diagnosed by prenatal detection and 8 were diagnosed after symptomatic urinary tract infections. Reflux was bilateral in 5 cases and unilateral in 7 (grades III to V in 7, 7 and 3, respectively). Controls included 10 age matched infants (median age 4 months) studied with the same urodynamic methodology.

Median cystometric bladder capacity expected for age +/- SD was 50% +/- 58% (range 20% to 240%). Bladder capacity was low (less than 80%) in 10 patients. Detrusor overactivity during filling was found in only 1 patient. In all except 1 case voiding alternated with peaks of high detrusor pressure (median 87 +/- 25 cm water), associated with intermittent external sphincter contractions with normal coordinated micturition (median 36 +/- 7 cm water). Cystometric residual urine (30% or greater) was noted in 3 cases. In 5 patients VUR occurred with an increase in bladder pressure, while in 7 it occurred during stable filling. No significant cystometric differences were found between patients with reflux and controls.

Most infants with VUR had decreased cystometric bladder capacity and normal detrusor activity during filling. High voiding pressure with concomitant sphincteric overactivity coexisted with normal micturition. This voiding pattern might represent a developmental stage of normal urine control and it may have a role in the etiology of reflux in some infants.