Prenatal Genetic Diagnosis through Chorionic Villus Sampling

Chor ion ic v i l l us sampl ing (CVS) i s a technique for prenatal diagnosis of the fetal karyotype through cytogenetic analysis, and of Mendelian inherited diseases through molecular or biochemical analysis. Because the sampling technique can be performed in the first-trimester of pregnancy and diagnostic results can be obtained earlier than with amniocentesis, it has been utilized by clinicians in Europe and the US since 1982. CVS includes two methods: a transcervical approach and a transabdominal approach. Both are performed in the 10th week of pregnancy under careful ultrasound guidance to prevent adverse effects, but in comparison with amniocentesis, a slightly higher risk of pregnancy loss has been reported. Moreover , diagnostic accuracy is often disturbed by maternal cell contamination and chromosomal mosaicism of the placenta. Therefore, clinicians must give patients sufficient information on such technical and diagnostic trouble through counseling in order to obtain fully informed consent.