CHORIONIC VILLUS SAMPLING

Chorionic villus sampling (CVS) has the great advantage over mid-trime ster amniocentesis of producing early results. Moreover, rapid analyti c techniques have significantly reduced the waiting time between sampl ing and diagnosis, whereas progress in recombinant DNA technology and human gene mapping has led to an increase in the range of conditions i t can detect. The role of CVS in twin pregnancy has been investigated and compared with amniocentesis. Although these techniques are equally safe, CVS should be considered the approach of choice because of a nu mber of technical advantages, and in relation to selective fetal reduc tion in discordant twins. Confined placental mosaicism has been invest igated and a list of chromosomes related to adverse pregnancy outcome has been compiled. Recent reports have substantially contributed to so lving the controversy on the hypothetical relationship between limb re duction defects and CVS. Analysis of limb reduction defects among more than 130 000 cases reported to the World Health Organization CVS regi stry has been unable to find any relationship between sampling and fet al malformations, including limb reduction defects.