Hematologic observations of the course of erythroblastosis fetalis

Serial studies revealed characteristic changes in the peripheral blood ofinfants with erythroblastosis fetalis. In the presence of elevated nucleated redcells and reticulocytosis, replacement transfusion brought about a momentarydecline to normal levels followed by a second rise during the succeeding threedays before the values returned to low levels. Platelet counts diminished withina day after replacement and only gradually rose toward normal after approximately three days. Such a picture was not seen in the mildly affected babies whodid not receive replacement therapy, in whom the platelet values varied.

Within the first three months in both groups anemia developed in the presenceof little evidence of compensating marrow activity. After a decline of the hemoglobin to an average level of 7.6 Gm. per cent, erythropoiesis became adequatefor return to normal levels. This hypoplastic defect could not be correlated withany other parameter of the disease.

Abnormalities were noted in the osmotic and mechanical fragility of the redcells in this disease. The major population of cells was found to be more susceptible to osmotic stress while the limits of hemolysis were within the normalrange. The osmotic curves of the blood of those patients who were not transfused returned to normal within 4 weeks. Mechanical fragility of the red cellswas increased in a significant number, and this abnormality was observed untilthe time when minimal hemoglobin values were reached. There was no correlation of these variations in fragility with other laboratory or clinical manifestations of the disease.

Submitted on December 17, 1954 Accepted on February 20, 1955