FETAL URINE PRODUCTION-RATES FOLLOWING INTRAUTERINE TRANSFUSION

This study investigates the hypothesis that following an intrauterine, intravascular transfusion (IVT), one of the physiologic adaptations m ight be an increase in the fetal urine production. The hourly fetal ur ine production rate (HFUPR) was measured for the first hour following 12 transfusions and for 24 h following 5 transfusions in anemic isoimm unized fetuses. The HFUPR was also measured in 5 control fetuses who u nderwent fetal blood sampling without transfusion. Fetal hemoglobin, h ematocrit and blood viscosity were measured before and after each tran sfusion. The HFUPR fell significantly from a mean (SEM) of 19.2 (2.85) to 7.4 (2.2) ml/h, and remained low for at least 4 h posttransfusion returning to pretransfusion rates by 24 h. There was no change in the HFUPR in the control fetuses. The study suggests that in human fetuses the rapid excretion of excess fluid via the renal tract is not an acu te adaptive response to an IVT.