[Ovum sampling techniques for prenatal diagnosis of viral infections]

Two techniques can be used to achieve antenatal diagnosis of viral infections, i.e., amniocentesis and cord blood sampling. these procedures and their risks to the fetus are described in this article. Amniocentesis can be performed at the 15th week after the last menstrual period (LMP) under ultrasonographic guidance and carries a risk of fetal death of approximately 0.5%. Cord blood sampling, more difficult technically, can be performed at the 18th week after the LMP but is not useful for the antenatal diagnosis of infectious diseases before the 22nd or 23rd weeks. Fetal death rate is 0.5 to 1% when the procedure is performed by experienced operators. Other sampling methods, including fetal sampling and chorionic villus sampling can be used only in specific clinical situations. Situations in which ovum sampling is appropriate are outlined according to the circumstances of discovery of viral infections and the general problems raised. Emphasis is put on the need to use detailed protocols to perform these sampling procedures in order to minimize fetal risks and effectively exploit collected data.