Hemolytic disease of the fetus and newborn (HDN) is a condition in which the lifespan of an infant's red blood cells (RBCs) is shortened by the action of specific IgG antibody (ies) derived from the mother directed against Rhesus or other blood group antigens on fetal RBCs that are inherited from the father but are not expressed by the mother. The widespread use of Rh immune globulin has dramatically decreased the occurrence of anti D-HDN among D negative pregnant women, but has not eliminated the problem. No measures are available to prevent sensitization to other blood groups, most notably other Rhesus (C,c,E,e), Kell and Duffy antigens. In this article, a case of anti-c incompatibility is presented and the issue of risks involving Rh negative blood transfusion in aloimmunized patients with anti-c is discussed.

Twin live babies named newborn1, sex female, and newborn2 were born from the 8th pregnancy of a 38 year-old brazilian mother from Pinhão-Paraná-Brazil through a normal vaginal route. Medical report of newborn1 during twenty days described levels of indirect bilirubin oscillating between 7 to 11 mg/dl and hemoglobin dropping from 13,9 to 10,1 g/dl without jaundice, phototherapy or transfusion registered. Thirty days postnatal, newborn1 had hemoglobin 7,7 g/dl and indirect bilirubin 11,3mg/dl and a blood transfusion was required. Antibody screen of the mother was positive and crossmatching with O negative blood was not compatible. Other tests, performed at Hemocentro Regional de Guarapuava-Paraná, identified mother's blood as A positive, phenotype C(+)c(-)E(-)e(+)K1(-), antibody screen detected anti-c antibodies with 1:256 titre. Baby's blood sample was identified as O positive, phenotype C(+)c(+)E(-)e(+)K1(-) with the direct anti-globulin test (DAT) positive (2+). After centrifugation with saline solution baby's sample after showed yellowed supernatant. A blood transfusion with 30 ml of O positive, c antigen negative blood, match compatible with the mother's serum, was transfused without reactions. At the hospital the mother revealed that these were her 8th and 9th children. Also, she said to be illiterate and that ignored her pregnancy until the 8th month and for it she simply did not have antenatal care. Unfortunately details about her other pregnancies could not be got.

Anti-c is an important Rh antibody that may cause severe HDN, and in some cases may be as severe as anti-D HDN. In a series of 1022 cases of non Rh D aloimmunization Kenneth found that only anti-c was associated with severe HDN that ended in hydropic stillbirth or necessitated intrauterine blood transfusion[1]. This was not the case presented in the article. Nevertheless, an important aspect embedded issue along with anti-c that goes unnoticed by many refers to the matter of Rh negative blood available for transfusion, including aloimmunized anti-c patients. The stereotype held by Rh negative blood as universal blood not applies to anti-c. If ones take into account the high incidence of c antigen both in Rh positive and Rh negative blood among the population, we can suppose that people having anti c antibodies, like the mother in the article, are sitted on an authentic powder keg where a transfusional mistake, either for misinformation or any reason can bring unexpected results.