Diagnostic and therapeutic technology assessment. Chorionic villus sampling

Chorionic villus sampling has a promising future as a means of early detection of fetal abnormalities. It has widespread application in Europe, and more than 6000 procedures have been performed in the United States. Universal acceptance of the procedure has been delayed because of uncertainties over the true fetal loss rate. Information available today indicates that the fetal loss rate should be in the same range as that for amniocentesis--approximately 1% or less. Confirmation of these estimates awaits release of the data from the large clinical trials currently under way. Modifications of the sampling technique are also under investigation. Transabdominal CVS can also be performed early in pregnancy (six to 15 weeks) with a fine-bore needle and cannula under ultrasonic guidance. It remains to be seen if this offers any advantages or incurs additional risks over transcervical CVS.