Chorionic villus sampling safety. Report of World Health Organization/EURO meeting in association with the Seventh International Conference on Early Prenatal Diagnosis of Genetic Diseases, Tel-Aviv, Israel, May 21, 1994.

Accumulated experience of 138,996 cases of chorionic villus sampling shows that chorionic villus sampling is a safe procedure with an associated fetal loss rate comparable to that of amniocentesis. The chorionic villus sampling registry shows that chorionic villus sampling is currently performed primarily between 9 and 12 weeks' gestation and carried no increased risk of limb reduction defects: the overall incidence of limb reduction defects after chorionic villus sampling is 5.2 to 5.7 per 10,000, compared with 4.8 to 5.97 per 10,000 in the general population. Analysis of the pattern distribution of limb defects after chorionic villus sampling revealed no difference from the pattern in the general population. This applies specifically to transverse limb defects. Together with the overall incidence of limb reduction defects, these data provide no evidence for any risk for congenital malformation determined by chorionic villus sampling. Because chorionic villus sampling is currently performed generally after 8 completed weeks of pregnancy, few data are available for analysis of complications related to earlier procedures. Avoiding early chorionic villus sampling also excludes sampling in cases of early fetal death, which can be diagnosed reliably by ultrasonography at 9 weeks of pregnancy.