Treatment of erythroblastosis fetalis by exchange transfusion: Statistical analysis of results

Abstract

Summary Among thirty-six stillbirths causedby Rh sensitization, all but one of the patients had Rh antibody titers of 16 units or higher by the albumin-plasma conglutination method. (In the single exceptional case, where the albuminplasma titrations were negative, it was possible to show that antibodies were present, but of an unusual type, since the titer was high by the antiglobulin and enzyme techniques.) Therefore, when using antibody titer as a criterion of severity, it was decided to consider 8 units by the albumin-plasma titration method as the upper limit for cases classified as “mildly” affected. The results of treatment by exchange transfusion in a series of 222 erythroblastotic infants were compared with the results obtained in a series of sixty-seven erythroblastotic babies who were left untreated or given one or more simple transfusions. Among “mildly” affected babies, i.e., those whose mothers had antibody titers of 8 units or less, no significant difference in the mortality rate in the two series was demonstrable. On the other hand, among severely affected babies treated by exchange transfusion, the mortality rate was 15.5±2.0 per cent, while among the babies receiving simple transfusions or no treatment, the mortality rate was as high as 46.4±6.2 per cent. The difference in mortality rate, 28.9±6.5 per cent, is statistically significant. During the past few years changeshave been introduced into our method of carrying out exchange transfusions. In the method now used by us, part of the citrated plasma is removed from bank blood not more than three days old, which has been allowed to sediment in the refrigerator in order to reduce the volume to 400 ml., and the resulting concentrated blood (hematocrit, approximately 0.50) is used for the exchange transfusion, equal volumes of blood being withdrawn and injected. In more severely affected babies, a second such exchange transfusion is given twenty-four to forty-eight hours after birth. Among seventy-eight erythroblastotic babics treated in this way, of whom fifty-three had mothers with antibody titers above 8 units by the albumin-plasma method, the mortality rate was only 5.1±1.6 per cent. (In this discussion, mortality rate is used to include neurological sequelae as well as deaths.) Case reports are presented in orderto illustrate the course of Rh sensitization in women followed through several pregnancies and to compare the results of treatment of several erythroblastotic babies born to the same mother. A case is cited which demonstrates the importance of icterus per se as a criterion of severity, and therefore this sign is a strong indication for treatment by exchange transfusion even in the absence of anemia. In view of the innocuousness of exchange transfusion carried out by the radial artery-saphenous vein technique and the excellent results obtained by this treatment, our tendency has been to widen the indications for its use in treating erythroblastotic babies.