Usefulness of Fetal Urine Production Measurement for Prediction of Perinatal Outcomes in Uteroplacental Insufficiency

Objectives: To evaluate whether fetal urine production measurement is useful for predicting adverse outcomes in patients with uteroplacental insufficiency.

Methods: We enrolled patients with uteroplacental insufficiency at 24 to 40 weeks' gestation and normal pregnancies matched for gestational age and divided them into 3 groups according to perinatal outcomes: group 1 (n = 141), a control group of normal pregnancies; group 2 (n = 29), uteroplacental insufficiency without adverse outcomes; and group 3 (n = 18), uteroplacental insufficiency with adverse outcomes. An adverse outcome was defined as 1 or more of the following: (1) cesarean delivery because of fetal distress; (2) admission to the neonatal intensive care unit; (3) cord arterial pH less than 7.15 at birth; and (4) low 5-minute Apgar score (<7). The fetal urine production rate was obtained by serial bladder volume measurement using virtual organ computer-aided analysis. For bladder volume determination, we scanned the bladder in the 3-dimensional mode and defined the bladder surface contour in the reference plane, repeating the rotation of the reference plane with an angle of 30° and determining the surface contour on each plane. Statistical methods, including the Mann-Whitney U test, Fisher exact test, χ(2) test, and Kruskal-Wallis analysis of variance, were used.

Results: Group 3 had a lower mean fetal urine production rate than groups 1 and 2, whereas the urine production rate was not different between groups 1 and 2 (group 1, 49.0 mL/h; group 2, 59.4 mL/h; group 3, 20.7 mL/h; P < .001 between groups 1 and 3 and between groups 2 and 3). This difference between groups 2 and 3 remained significant after adjusting for the amniotic fluid index, umbilical artery Doppler pulsatility index, and presence of fetal growth restriction.

Conclusions: Uteroplacental insufficiency cases with adverse perinatal outcomes had a lower fetal urine production rate than those without adverse outcomes. This difference might be used to predict adverse perinatal outcomes in uteroplacental insufficiency.