Despite the development and implementation of Rh(D) immune globulin prophylaxis, maternal rhesus (Rh) alloimmunization is still a cause of hemolytic disease of the fetus and newborn. However, with appropriate monitoring and intervention, this disorder can be treated successfully in almost all cases, with no long-term sequelae in offspring.
This topic will provide an approach to management of pregnant women with Rh(D) alloimmunization. Alloimmunization to other Rh antigens (c, C, e, E, G) is managed in a manner similar to that described below for Rh(D) alloimmunization, although data supporting this approach are sparse and primarily consist of case reports and small series [1-3]. Related topics, including a discussion of the Rhesus system, diagnosis and prevention of Rhesus alloimmunization, in utero transfusion, and neonatal issues, are reviewed in detail separately:
Ideally, alloimmunized pregnant women should be monitored by a Maternal-Fetal Medicine specialist with experience managing this now rare complication and who is credentialed to perform the invasive diagnostic and therapeutic procedures that may be needed. An algorithm describing our approach to managing pregnancies complicated by alloimmunization is provided in the figure (algorithm 1) .
An Rh(D)-negative fetus is not at risk of complications from maternal anti-D antibodies; therefore, the first step in antenatal management of maternal alloimmunization is to test paternal blood, which will help predict the fetal Rhesus type.