Diagnostic and therapeutic technology assessment. Chorionic villus sampling: a reassessment.

Abstract

The Canadian and National Institute of Child Health and Human Development trials as well as other nonrandomized studies indicate that CVS is both safe and effective. Fetal loss rates have been slightly higher with CVS (6 to 8 more losses per 1000 procedures), but none of these results were statistically significant. Chorionic villus sampling also probably has a slightly higher procedure failure rate than amniocentesis. The DATTA panelists are now confident that the safety of CVS approaches that of amniocentesis and that the higher procedure failure rate is offset by the opportunity of earlier diagnosis with CVS. Transcervical CVS is often preferred by women because it offers an opportunity for early prenatal diagnosis and early intervention if necessary. It is performed as an outpatient procedure and is relatively simple for the patient; however, the practitioner requires special training in CVS. Modifications of the sampling technique are also under investigation. Transabdominal CVS can also be performed early in pregnancy with a fine-bore needle under ultrasonic guidance. It may be used in cases where the placenta is inaccessible to the transcervical approach or there is vaginal infection.