Increased risk of aneuploidy in women having unsuccessful chorionic villus sampling procedures

OBJECTIVE: To determine the incidence of fetal aneuploidy in women who had unsuccessful chorionic villus sampling (CVS) procedures. DESIGN: Retrospective study. SETTING: Pennsylvania Hospital, Philadelphia, Pennsylvania, USA. SUBJECTS: Two thousand six hundred and sixty-eight women who underwent chorionic villus sampling, in 78 (2.9%) of whom villi could not be obtained. INTERVENTIONS: Sixty-nine of 78 (88%) women who had an unsuccessful CVS procedure underwent a subsequent amniocentesis later in the same pregnancy. MAIN OUTCOME MEASURES: The incidence of aneuploidy identified from amniotic fluid chromosome analysis in the 69 women who had an unsuccessful CVS procedure compared to the frequency of aneuploidy in women having a successful CVS procedure. RESULTS: Of the 69 women who underwent a post-CVS amniocentesis because of failure to obtain chorionic villi, six aneuploid pregnancies were identified (8.7%). The frequency of aneuploidy in the 2590 successfully sampled CVS patients was 2.5%. This difference was statistically significant (P = 0.009) by Fisher's exact test (two-tailed). CONCLUSIONS: Women having an unsuccessful CVS procedure should be informed that they may be at increased risk for carrying an aneuploid fetus.