Chorionic Villus Sampling: Clinical Experience of the Initial 750 Cases

OBJECTIVE: To assess the factors that might influence the success rate, safety and reliability of chorionic villus sampling (CVS) and to evaluate the relationship between CVS and other congenital anomalies. DESIGN: Analysis of the outcome of 750 cases of CVS (730 cases with transcervical and 20 cases with transabdominal). SETTING: The outpatient prenatal genetic clinic of a university tertiary care center. SUBJECT: Seven hundred and fifty pregnant women that underwent CVS for prenatal genetic diagnosis from 7 to 12 weeks of gestation. RESULTS: Advanced maternal age was the most common indication for CVS (32.8%). The overall sampling success rate was 98.0% (735/750), representing 93.9% at 7 to 8 weeks, 98.1% at 9 to 10 weeks, and 98.3% at 11 to 12 weeks of gestation. The majority of cases (93.1%) required one or two aspirations. Cytogenetic analysis routinely included direct overnight and long-term culture methods which revealed 16 abnormalities (2.2%). Of 735 cases in which CVS was successful, 700 advanced to normal offspring, 17 had therapeutic termination, and 18 resulted in spontaneous abortions; there was an overall fetal loss rate of 2.4% (18/750). CONCLUSION: CVS in early pregnancy is a relatively safe and reliable method of prenatal genetic diagnosis capable of replacing genetic amniocentesis. However, it must be done by experienced personnel. No congenital anomalies were found to be related to CVS in this series.restrictio