Definition

Refers to the abnormal accumulation of fluid in the skin, body cavities, umbilical cord, and placenta of an unborn baby. Hydrops fetalis (HF) can result from many different diseases and structural defects. HF is traditionally divided into two major categories: immune HF and nonimmune HF. Immune hydrops fetalis is caused by Rh incompatibility, and was the most common cause of HF until the advent of anti-Rh antibody treatment (RhoGAM®) during pregnancy. All other causes of HF are termed nonimmune HF. Nonimmune hydrops fetalis may be caused by chromosomal aberrations, other genetic disorders, infections, anemias, structural birth defects such as congenital heart disease, and many other conditions. Currently in the United States nonimmune HF consists of about 90% and immune...