Use of red cells preserved in extended storage media for exchange transfusion in anti-k haemolytic disease of the newborn.

Anti-k is a Kell-related antibody. There is little correlation between the maternal antibody titre and the severity of haemolytic disease of the foetus and newborn, and anaemia is usually associated with low bilirubin levels. Severe erythroblastosis has been reported with a low titre anti-k (IAT 8-16). We report a case of severe haemolytic disease of the newborn (HDN) due to anti-k. HDN was associated with a normal bilirubin level and reticulocytopenia. The foetus was monitored by ultrasound, and delivery by elective caesarean section (CS) was planned. The mother was admitted 1 week before the expected date of delivery, and the infant was delivered by urgent CS. The infant required exchange transfusion. As suitable plasma-reduced (k antigen(-)) red cell units were not readily available, k- SAGM red cell units (preserved in extended storage media: SAGM sodium chloride, adenine, glucose and mannitol) were provided. The post-transfusion Hb remained stable, and the infant did not require further transfusion support. Our findings (reticulocytopenia and normal bilirubin levels) support the hypothesis that the pathogenesis of anaemia and haemolysis in anti-k HDN may be similar to that in anti-K (suppression of erythropoesis and immune destruction of K+ erythroid progenitor cells by macrophages in the foetal liver). The ideal product for exchange transfusion is plasma-reduced RBC, less than 5-days old. We provided a 4-day-old SAGM red cell unit for exchange transfusion in a term infant, and this was uneventful. Caution should be taken, however, and renal function and electrolyte levels should be monitored closely. More information is required regarding the safety of SAGM units for exchange transfusion.