The voiding pattern of healthy preterm neonates.

PURPOSE

To elucidate further the maturation of voiding habits from gestation to infancy we investigated the free voiding pattern of healthy preterm neonates.

MATERIALS AND METHODS

We evaluated 11 male and 8 female healthy preterm newborns at a mean of 32 weeks after cessation of menstrual flow (postmenstrual age). Assessment was done in the neonatal ward using 4-hour voiding observation, a method described previously in studies of free voiding pattern of full-term newborns.

RESULTS

The voiding pattern of male and female preterm neonates was characterized by 1 void per hour and a mean voided volume of 53% of bladder capacity with 58% frequency of interrupted voiding. Residual urine was increased but varied during observation (mean 11% bladder capacity) and was 0 after at least 1 void during 4 hours in 14 of the 19 subjects. Two-thirds of all voiding occurred during sleep, whereas a third of the newborns showed signs of arousal with a mean awake time of only 17 minutes.

CONCLUSIONS

The voiding pattern of preterm versus full-term subjects is characterized by an increased number of interrupted voidings, further indicating that these voidings represent immature behavior of detrusor-sphincter coordination. Also, the high number of voidings during sleep suggest a more immature pattern for preterm newborns.