[Alpha fetoprotein and HbF cells in the maternal blood and their modification through amniocentesis].

In 101 patients of the Frauenklinik der Medizinischen Hochschule Hannover we have measured the concentrations of fetal cells and alpha-fetoprotein before and after amniocentesis. There was a significant increase in both parameters corresponding to an arbitrary fetomaternal haemorrhage of 0,05--0,4 ml. AFP seemed to be more reliable than the fetal cell count. The site of placentation was of no influence on the fetomaternal haemorrhage. As less than 0,1 ml rhesus-positive fetal blood is enough to cause isoimmunization in mothers at risk we highly recommend to give immunoglobulin-anti-D to all unsensitized rhesus-negative mothers after amniocentesis.