RESUMO
ABO incompatibility has emerged as the premier reason for hemolytic disease of the fetus and newborn (HDFN). It always occurs in the offspring of blood group O mother. We present a rare case that the fetus of group A got HDFN caused by the anti-group A immunoglobulin G from a group B mother. The direct Coombs test of the fetus blood was negative, but the indirect Coombs test on A1 standard blood cells was strong positive (4+). The acid release test of antibody on the membrane of red blood cells to A1 standard blood cells was also strong positive (4+). Bilirubin of the fetus reached the threshold of exchange transfusion, but she just received 4 days' phototherapy and 2.2 g albumin intravenous injection, with no packed blood cells transfusion, because her family refused, and came to a favorable outcome. This case reminds us not to ignore the possibility of HDFN in offspring of mothers with non-O blood group.