RENAL AND AMNIOTIC-FLUID RESPONSES TO UMBILICOPLACENTAL EMBOLIZATION FOR 20 DAYS IN FETAL SHEEP

We determined the effects of placental insufficiency induced by umbili coplacental embolization on fetal. renal function and amniotic fluid v olume and composition. Pregnant ewes underwent surgery at 115 +/- 2 da ys after mating (term similar to 147 days) for implantation of fetal v ascular, bladder, and amniotic sac catheters. We studied five fetuses from 120 to 140 days during umbilicoplacental embolization and six con trol fetuses. Umbilicoplacental embolization reduced fetal arterial pa rtial pressure of oxygen from 24.1 +/- 0.5 mmHg (pretreatment) to 14.6 +/- 0.2 mmHg. Fetal body weights were reduced to 80% of control value s. Urine production and glomerular filtration rate in treated fetuses were significantly lower than in controls at 135 days of gestation. Am niotic fluid volume was not different between embolized and control an imals. Fetal urine production in Created fetuses, when adjusted for bo dy weight, was not different from that in control fetuses. We conclude that, in fetal growth restriction, reduced kidney weight, rather than hypoxemia per se is responsible for reduced urine production, which, if severe and prolonged, may contribute to oligohydramnios.