Fetal Hydrops

Fetal Hydrops is when the uterus is too large for dates (large-for-date fetus) and is caused by the following features: fetal edema or skin thickness (macrosomia), polyhydraminous, ascites (liver, abdomen), pericardial effusion, pleural effusion, and abnormally large placenta. In ultrasound, the large placenta would appear homogenous and echogenic. This would occur during Rh incompatibility (mixing of maternal blood and fetal blood btw Rh- and Rh+).

When the mother has Rh- blood and the fetus has Rh+, the blood mixes together and this is termed immune hydrops. However, the mixing of Rh blood will not damage the fetus in the first pregnancy. During the second pregnancy, the anti-bodies produced in the first will attack the fetal red blood cells thereby harming the baby and is called erythroblastosis fetalis. In non-immune hydrops, the two of the six features of fetal hydrops previously mentioned are seen (ie. polyhydraminous, ascites).