[Misinterpretation of alpha-fetoprotein (AFP) values in amniotic fluid due to fetal hemorrhage (author's transl)].

The AFP concentration in the amniotic fluid is elevated after contamination of the sample with fetal blood during a traumatic amniocentesis. Though the calculation of AFP due to fetal hemorrhage is possible by counting the fetal red cells there may be execssive errors resulting from the variability of fetal red cell count, amniotic volume, fetal serum AFP concentration, AFP concentration in the amniotic fluid changing with fetal age. Therefore it is impossible to interpretate elevated AFP values from a sample stained with fetal blood. A repeated amniocentesis is unavoidable. The correct time to do a second punction is still a matter of question.