Prenatal cytogenetic diagnosis. Amniotic cell culture versus chorionic villus sampling.

Chorionic villus sampling is under evaluation throughout the world. Amniocentesis with amniotic cell culture is reliable for the diagnosis of certain types of genetic disease in the second trimester, and has been the subject of extensive clinical and laboratory audit. Chorionic villus sampling has the advantage of the early diagnosis (for example, at 10 weeks) of chromosomal abnormalities, a shorter delay with results after the diagnostic procedure, and is, for some couples, a more socially and morally acceptable method of antenatal diagnosis. In current experience, the disadvantages of chorionic villus sampling include an increased fetal loss and an increased diagnostic error rate. Another factor is the early diagnosis of fetuses with chromosomal abnormalities--a proportion of whom would have miscarried spontaneously before being detected at an amniocentesis at 16 weeks. This has implications for an increased rate of therapeutic terminations of pregnancy. Chorionic villus sampling and amniotic cell culture are discussed and comparisons are drawn that concern the clinical advantages and diagnostic issues which are inherent in each method of prenatal diagnosis.