Hemolytic Disease of the Fetus and Newborn (HDFN) is an alloimmune disease which develops in a fetus when a women’s immune system is sensitized, developing antibodies which cross the placenta and attack fetal RBCs. 

While there is a spectrum of the disease, in severe cases the fetus can ultimately develop hydrops fetalis which is often fatal.

As Emergency Physician’s we are classically taught that we can help to prevent HDFN by recognizing sensitizing events in Rh-negative women and subsequently providing RhoGAM. But which patients really need RhoGAM? The evidence seems to be lacking and recommendations are often inconsistent.