Purpose: Urinary tract infections and vesicoureteral reflux are more common in male than female infants. Since these problems can result from voiding dysfunction, we obtained a detailed history of voiding patterns and urodynamic testing in infants with urinary tract infections in the first year of life.
Materials and methods: We evaluated 39 male and 22 female infants, including 40 with primary vesicoureteral reflux and 21 with no reflux or obstruction.
Results: Voiding abnormalities were noted in 97% of the male and 77% of the female infants, including high voiding detrusor pressure of greater than 40 cm. water in 92% of the male and 66% of the female infants, residual urine greater than 2 ml./kg. in 13% of the male and 23% of the female infants, and detrusor hyperreflexia with filling pressure greater than 40 cm. water in a third of the male infants. Voiding detrusor pressure was significantly higher in male than female infants and in male infants with grade IV to V reflux than those with lower grades of reflux or no reflux. Followup urodynamic testing in 15 infants with high voiding detrusor pressure revealed resolution of detrusor hyperreflexia and improvement in post-void residual in all and decreased voiding detrusor pressure in 14.
Conclusions: We coined the term transient urodynamic dysfunction of infancy to describe this constellation of abnormalities, which predisposes infants to urinary tract infections and vesicoureteral reflux but improves spontaneously. The higher incidence of urinary tract infections and reflux in male infants may be related to higher intravesical pressures.