A retrospective and theoretical evaluation of rapid methods for detecting chromosome abnormalities and their implications on genetic counseling based on a series of 3868 CVS diagnoses.

OBJECTIVES To report our experience over the past 10 years of chorionic villi sampling (CVS) prenatal diagnosis in a high-risk population for chromosomal anomalies, and to analyze, according to the results, the advantages and disadvantages of using quantitative fluorescence polymerase chain reaction (QF-PCR) in amniotic fluid with respect to a conventional semi-direct cytogenetic CVS method in a retrospective theoretical review. METHODS We performed 3,868 cytogenetic analyses from CVS using a semi-direct culture method in a selected high-risk population for chromosomal abnormalities and we compare our findings with the theoretical results obtained using QF-PCR on amniotic fluid. RESULTS The rate of chromosomal anomalies detected with the semi-direct CVS cytogenetic study, excluding confined placental mosaicism (CPM), was 6.8%. 26.3% of all them would be missed by using QF-PCR only and among them, 21.4% of cases would represent a severe adverse obstetric outcome. CONCLUSIONS We think that semi-direct CVS cytogenetic analysis in comparison with QF-PCR in amniotic fluid is similarly rapid, performed earlier and more complete, allowing the chromosomal diagnosis in the first trimester of gestation. We propose the use of QF-PCR as an additional method to semi-direct CVS analysis in order to avoid false-negative results, as a rapid alternative to long-term culture.