Coagulation Failure in Babies with Rhesus Isoimmunization

S ummary . Serial prospective studies of coagulation status have been undertaken on 73 babies with a positive Coombs test. No abnormalities were detected in the babies with mild haemolytic disease, but seven of the 36 babies with severe haemolytic disease (cord Hb < 11 g/dl or cord bilirubin > 85 μmol/l) showed evidence of transient defibrination 1 d after birth and another six had evidence of coagulation failure at birth with a platelet count of less than 150 × 10 9 /l and a severe deficiency of multiple coagulation factors. The level of factor II and factor X was less than a fifth of the normal cord blood level in these six babies and the level of I, VII and IX was severely reduced; the factor VIII level was normal or high. Exchange transfusion started within 1 h of birth corrected the immediate factor deficiency in these six babies, but evidence of defibrination then became apparent with afibrinogenaemia, a marked fall in factors II and V, less constant falls in factors VII, IX and X, and a raised fibrin: fibrinogen degradation product level. One of these six babies died with severe pulmonary hypoplasia within an hour of birth; the other five died from haemorrhage into the lung or brain 1 1/2–6 d after birth. The very low vitamin‐K dependent factor levels in the cord blood of the babies who died are presumably the result of liver damage in utero , but the subsequent changes are those of a comsumption coagulopathy. Simple screening tests at birth served to indicate which babies were at risk and it is concluded that death due to haemorrhage might be reduced by more intensive factor replacement before there is overt evidence of haemorrhage in these babies.