Intraperitoneal fetal transfusion: paralysis inhibits red cell absorption.

This study was undertaken to determine whether differences in fetal activity could account for the unpredictability of absorption of red blood cells from the peritoneal cavity of fetuses with alloimmune hydrops. The absorption of red cells from the peritoneal cavity of fetal lambs was studied in 7 pregnant ewes. In 3 nonparalyzed fetuses, uptake of donor red cells was complete by 80 h. In 4 fetuses given pancuronium for 4 days to abolish breathing and body movements, the absorption of red cells was markedly diminished at 92 h, but was complete 3-4 days after fetal movement resumed. This study demonstrates that fetal movements are essential in ensuring the normal absorption of red cells from the peritoneal cavity. Variability in fetal movements, particularly fetal breathing movements, may explain the unpredictability of absorption of red cells from the peritoneal cavity in fetuses with hydrops fetalis.

Normal values for human umbilical venous and amniotic fluid pressures and their alteration by fetal disease.

Umbilical venous and amniotic fluid pressures were measured in 68 human pregnancies at the time that cordocentesis was performed. Normal umbilical venous pressure was unrelated to gestational age and remained within a tight range (5.3 +/- 2.3 mm Hg, mean +/- SD). Fetuses with an elevated umbilical venous pressure had disorders consistent with either hepatomegaly or congestive heart failure. Umbilical venous pressure was significantly increased before treatment in two fetuses with immune hydrops; it rapidly declined with treatment. Neither gestational age nor umbilical venous pressure was significantly different in the groups that received and did not receive pancuronium. There was a strong relationship between amniotic fluid pressure and gestational age in normal pregnancy (r = 0.54, p less than 0.0001). Women with hydramnios had amniotic fluid pressures greater than control subjects (p = 0.0007). This investigation documents normal human amniotic fluid and fetal umbilical venous pressures. These measurements are altered by disease and may prove to be of diagnostic and therapeutic value in the future.