ANTIBODY PROTEIN LEVELS IN THE MATERNAL SERUM IN RHESUS ISO-IMMUNIZATION

Summary

Automated serum antibody protein estimations proved to be a reliable index of the need for amniocentesis in expectant mothers with rhesus antibodies. In those who develop rhesus antibodies for the first time, amniotic fluid examination is indicated if the antibody protein value in the serum reaches 1.5 μg per ml. or more before 35 weeks of gestation. Using this technique instead of manual indirect antiglobulin tests the proportion of mothers requiring amniocentesis fell from 45 to 35 per cent. When a previous baby has been affected amniocentesis is indicated if the antibody protein level reaches 1.0 μg per ml. or more before 35 weeks of gestation. In this group of patients the replacement of manual by automated techniques decreased the proportion of mothers requiring amniocentesis from 56 to 51 per cent. There was a good correlation between the maternal serum antibody protein level and the degree of haemolytic disease in the newborn baby. In 2 of the 600 pregnancies studied the maternal serum contained a bromelin inhibitor; prior treatment of the test cells with bromelin overcame the problem that this inhibitor caused.