Prenatal diagnosis by chorionic villus sampling

Chorionic villus sampling (CVS) retains its great advantage over mid-trimester amniocentesis by producing early results. Moreover, rapid analytical techniques reduce significantly the waiting time between sampling and diagnosis, while recombinant DNA technology and human gene mapping progress amplify enormously the spectrum of the indications. The recent inclusion in the prenatal diagnosis package of screening tests based on DNA analysis for the major genetic diseases (i.e. cystic fibrosis, fragile-X mental retardation syndrome) may efficiently contribute to prevent the genetic disease. The role of CVS in twin pregnancy has been investigated and compared to amniocentesis. Although these techniques are equally safe, CVS should be considered the approach of choice for a number of technical advantage and in relation to selective fetal reduction in discordant twins. Recent reports have substantially contributed to the controversy on the hypothetical relationship between limb reduction defects (LRDs) and chorion biopsy. The analysis of LRDs among more than 130 000 CVS reported to WHO CVS-Registry has been unable to find out any relationship between sampling and fetal malformations, including LRDs. In conclusion, first trimester CVS should be considered the gold standard procedure for prenatal diagnosis of genetic diseases.