Circulating cell-free DNA levels increase variably following chorionic villus sampling.

OBJECTIVE: Cell-free fetal DNA (cffDNA) in maternal plasma results from degradation of fetal and/or placental cells. Our objective was to determine if chorionic villus sampling (CVS) causes increased release of fetal and/or maternal DNA. METHODS: Fifty-two pregnant women were recruited prior to CVS, performed for clinical indications, at 10 5/7 to 13 2/7 weeks. Maternal blood was collected before and within 15 min after CVS. cffDNA was extracted from plasma. Real-time polymerase chain reaction (PCR) amplification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the Y chromosome sequence DYS1 were used as measures of total and fetal DNA, respectively. All samples were analyzed in triplicate without knowledge of fetal gender. RESULTS: Sensitivity of DYS1 detection in male fetuses was 100% (n = 30); specificity in female fetuses was 100% (n = 22). While a majority of women had > 50% post-procedure increases in both fetal and total DNA, some showed post-procedure decreases. However, overall median proportional increases were not statistically significant. Gestational age (GA), placental location, and individual CVS operator did not correlate with changes in DNA levels. CONCLUSIONS: While there were no statistically significant overall changes in DNA levels after CVS, as-yet undiscovered variables may influence the extent of post-procedure release of cell-free DNA in the circulation of pregnant women.