Rh incompatibility

Maternal antibodies produced in response to paternally derived D antigens on fetal red blood cells are the leading cause of severe haemolytic disease of the fetus and newborn (erythroblastosis fetalis).

Effective immunoprophylaxis of rhesus D-negative at-risk mothers is key to primary prevention.

Intrauterine fetal transfusion is a life-saving treatment for severely affected fetuses.

Survival rates are more than 90%.

Rhesus (Rh) incompatibility is caused by destruction of fetal red blood cells (RBCs) from transplacental passage of maternally derived immunoglobulin G (IgG) antibodies. IgG antibodies are produced by the maternal immune system, usually against the RhD antigen. These antibodies can freely cross the placenta, binding to and destroying RBCs. More than 50 known RBC antibodies potentially cause Rh incompatibility. The consequence is progressive fetal anaemia, which, untreated, may ultimately lead to hydrops fetalis (collection of fluid in serous compartments) and death.[1]Hadley AG. In vitro assays to predict the severity of hemolytic disease of the newborn. Transfus Med Rev. 1995 Oct;9(4):302-13. http://www.ncbi.nlm.nih.gov/pubmed/8541713?tool=bestpractice.com [2]Bromilow IM, Downing I, Walkinshaw SA, et al. A case of unexplained mild Rh (D) haemolytic disease in utero. Transfus Med. 1995 Mar;5(1):31-5. http://www.ncbi.nlm.nih.gov/pubmed/7767395?tool=bestpractice.com [3]Brennand J, Cameron A. Fetal anaemia: diagnosis and management. Best Pract Res Clin Obstet Gynaecol. 2008 Feb;22(1):15-29. http://www.ncbi.nlm.nih.gov/pubmed/17904904?tool=bestpractice.com