Acrobat
MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Antibody Screen Positive: Rh Disease and Other Atypical Antibodies
Sponsored by The Indian Health Service Clinical Support Center
4. Rh Disease and Other Atypical Antibodies
Step 4. How does Rh sensitization occur? Why fetal anemia
How does Rh sensitization occur and why does it cause fetal anemia?
The process resulting in hemolytic disease of the newborn begins as a result of feto-maternal hemorrhage, most of which are subclinical, and which are increasingly common events as pregnancy advances. (Jabara)
As little as 0.1 mL of fetal erythrocytes containing the RhD antigen may stimulate the maternal immune system and result in subsequent Rh alloimmunization. The maternal antibody (anti-D) is of the IgG class that can cross the placenta. (Jones)
It may thereby affect the Rh positive fetus if a new antigenic exposure occurs in a subsequent pregnancy. Rhesus hemolytic disease results when maternal antibody attaches to D-antigens on Rh positive fetal red cells, resulting in red cell lysis and fetal anemia. The greatest admixture of maternal and fetal cells occurs during placental separation at birth, but sensitization can occur from more minor events.
