Anti-Fya causing indirect Coombs test positive in an RhD-negative mother: A case that highlights the importance of rare donor registry

This case report shows a rare occurrence of hemolytic disease of the fetus and newborn caused by anti-Fy(a) antibodies in a RhD-negative pregnant woman. Although the indirect Coombs test (ICT) was positive, initial screening did not detect the specific antibody, as routine follow-up often focuses only on anti-D. Crossmatch incompatibility during preoperative blood preparation led to extended antibody screening, which identified anti-Fy(a) antibodies. All the RhD-negative units (a total of 13) were found incompatible. O-negative Fya-negative individuals were searched from rare donor registry and their blood became compatible. The mother delivered twins via elective cesarean section, both of whom showed signs of hemolysis and jaundice, with positive direct Coombs tests and elevated bilirubin levels. Duffy phenotyping confirmed the presence of Fy(a) antigen on the neonate’s red blood cells. Both infants recovered following phototherapy. This case emphasizes the need for broader antibody screening beyond anti-D in ICT-positive pregnancies to detect clinically significant non-D antibodies and prevent avoidable neonatal complications.