Unusual markedly-dilated chorionic vessels with placentomegaly

We reported a very rare case with placentomegaly and markedly-dilated chorionic vessels. A 23-year-old Japanese pregnant woman was referred to our hospital at 32 weeks of gestation because of suspected dilatation of the umbilical vein. Ultrasound revealed fetal growth restriction with no fetal anomalies. The placenta was thick. The umbilical cord had two arteries and one vein, and marginal insertion of the umbilical cord in the placenta was suspected. A lot of remarkably tortuous tubular structures were observed on the surface of the placenta. Slow blood flow, indemonstrable with color Doppler, was observed within them. Labor started suddenly and progressed very rapidly at 33 weeks of gestation. A female infant weighing 1524 g was delivered. The infant had no malformations. However, she showed hypotension, anemia and DIC and required blood transfusion. The placenta was very large, weighing 1416 g. On the fetal surface, numerous dilated and tortuous vessels were observed, arising from a vein that was connected to the umbilical vein. These venous channels were dilated and tortuous and led into the placenta. In conclusion, prenatal diagnosis of placentomegaly and markedly-dilated chorionic vessels requires assessment of growth, anemia and DIC of the fetus and the newborn infant.