The voiding pattern of healthy preterm neonates

Purpose: To elucidate further the maturation of voiding habits from gestati on to infancy we investigated the free voiding pattern of healthy preterm n eonates. Materials and Methods: We evaluated 11 male and 8 female healthy preterm ne wborns at a mean of 32 weeks after cessation of menstrual flow (postmenstru al age). Assessment was done in the neonatal ward using 4-hour voiding obse rvation, a method described previously in studies of free voiding pattern o f full-term newborns. Results: The voiding pattern of male and female preterm neonates was charac terized by 1 void per hour and a mean voided volume of 53% of bladder capac ity 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 ch aracterized by an increased number of interrupted voidings, further indicat ing that these voidings represent immature behavior of detrusor-sphincter c oordination. Also, the high number of voidings during sleep suggest a more immature pattern for preterm newborns.