UMBILICAL VENOUS-PRESSURE IN NORMAL, GROWTH-RETARDED, AND ANEMIC FETUSES

OBJECTIVE: Our purpose was to establish a reference range with gestati on for umbilical venous blood pressure and to examine possible changes in intrauterine growth retardation and red blood cell isoimmunization . STUDY DESIGN: Umbilical venous pressure was measured at cordocentesi s in pregnancies complicated by intrauterine growth retardation (n = 2 0) and red blood cell isoimmunization (n = 61) both before and after i ntravascular fetal blood transfusion. The values were compared with a reference. range that was constructed from the study of 111 pregnancie s undergoing prenatal diagnosis at 18 to 40 weeks' gestation. RESULTS: In the control group the mean umbilical venous pressure increased sig nificantly with gestation. In the growth-retarded fetuses umbilical ve nous pressure was higher, normal, or decreased, and there was no signi ficant association between umbilical venous pressure and either fetal size or degree of acidemia. In the pregnancies complicated by red bloo d cell isoimmunization umbilical venous pressure increased with anemia but decreased to normal in the most severely anemic and hydropic fetu ses. After intravascular blood transfusion umbilical venous pressure i ncreased in proportion to the improvement in fetal hemoglobin concentr ation. CONCLUSION: Umbilical venous pressure is not the equivalent of central venous pressure but reflects both left and right heart functio n and placental resistance.