Histometric case report of a placenta following intra-uterine therapy of rhesus incompatibility

In Rh-incompatibility the human placenta shows a prominent retardation of maturation. The placental insufficiency caused by these changes, combined with the existing hemolysis, represents an additional danger to the fetus. In a patient with severe Rh-incompatibility several Rh-negative blood transfusions were performed between the 26th and 30th weeks of gestation via sonographically guided puncture of the umbilical vein. Morphometric studies of the placenta were performed and the results compared with data already obtained from normal mature placentas and placentas from pregnancies complicated by Rh-incompatibility. Small terminal villi with a surface area identical to normal mature placentas were found. There was no improvement in vascularization when compared with other placentas from Rh-incompatible pregnancies. Nevertheless, isolated rebuilding of epithelial plates was found. The authors interpret these morphological phenomena as a "partial postmaturation" of the placenta as regards the development of the terminal villi. The absence of reproliferation of the villous vessels as well as the lack of any extensive regeneration of the epithelial plates could be due to the short time which elapsed between transfusion therapy and the inevitable indication for caesarean section. Intensive intrauterine therapy reduces the risk to the fetus due to immunologic complications, as well that due to placental insufficiency, as evidenced by the additional differentiation of villi.