[On the feto-maternal transfusion of red blood cells during transplacental and para-placental genetic amniocenteses (author's transl)].

The concentrations of fetal hemoglobin (HbF) containing red blood cells in the peripheral blood of the mothers was studied in 113 cases by the method of Kleihauer & Betke prior and following trans-abdominal amniocenteses for genetic reasons between 15 and 18 weeks of pregnancy. Prior to the amniocentesis, 25% of the patients had HbF positive cells. Following the amniocentesis 36% of the patients showed HbF positive cells. In one out of six amniocenteses a measurable increase of the concentration of HbF containing red blood cells by approximately 0.22% was detected. These increases are within the limits found prior to amniocentesis and are not significant. There was no difference in the incidence and level of microtransfusions between paraplacental and transplacental amniocenteses. Because of the possibility of Rh sensitization Rh negative mothers should receive Rh immunoglobulin. None of the 112 patients had an abortion within two weeks following the amniocentesis.