Journal of Ultrasound in Medicine, Vol 17, Issue 9 539-544, Copyright © 1998 by American Institute of Ultrasound in Medicine
Effect of maternal hydration on mild fetal pyelectasis
C. J. Babcook, M. Silvera, C. Drake and D. Levine
Department of Radiology, The University of Utah Medical Center, Salt Lake City 84132, USA.
The aim of our study was to determine whether maternal hydration status
prior to prenatal sonography affects fetal renal pelvic diameter. The renal
pelvic diameters of fetuses from two different institutions were compared
prospectively. At one institution 74 women were asked to drink 32 to 48
ounces of water prior to undergoing sonography (hydration group), whereas
at the second institution, no specific hydration regimen was requested of
176 subjects. The inclusion criteria were as follows: greater than 15
weeks' gestation, otherwise normal obstetrical sonogram, normal amniotic
fluid volume, and negative family history for renal disease. Renal pelvic
diameter, degree of maternal bladder fullness, and gestational age were
compared between the two groups using logistic regression analysis and
log-linear analysis. A P value < 0.01 was considered significant.
Bladder fullness in the two groups differed significantly (P < 0.001).
Logistic regression analysis showed a very strong effect of maternal
bladder fullness on fetal renal pelvic diameter (P < 0.001). The
log-linear analysis model showed a highly significant association between
maternal bladder fullness and fetal renal pelvic diameter (P < 0.001).
We conclude that maternal hydration influences fetal renal pelvic diameter.
The larger fetal renal diameters seen in the hydrated group support
physiologic theories that the effects of maternal hydration on amniotic
fluid volume are partially mediated via fetal urine production.
