Invasive prenatal diagnosis in the era of cell-free fetal DNA: experience at a single center.

Background: We aimed to assess procedure-related risk of fetal loss associated with amniocentesis and chorionic villus sampling and compare amniocentesis and chorionic villus sampling with cell-free fetal DNA in identifying chromosomal abnormalities.

Methods: A retrospective observational study on 4712 women with singleton pregnancy who underwent invasive prenatal diagnosis, from January 2010 to December 2019. Postprocedural miscarriage rate (before 24⁺⁰ weeks gestation) was determined for the whole population and for the group of women aged ≥35 years who underwent the procedure for the sole maternal age.

Results: Miscarriage rate following amniocentesis and chorionic villus sampling were 0.50% and 1.25%, respectively. In our population of women undergoing invasive procedure for advanced maternal age cell-free fetal DNA would have identified only the 49 cases of trisomy 21, 13 and 18, whereas the other 21 more subtle chromosomal anomalies, diagnosed by amniocentesis and chorionic villus sampling, would have been missed.

Conclusions: Patients who opt for cell-free fetal DNA test should be informed of the screening nature of the test and the possibility of false positive results. Invasive prenatal testing has probably lower risks than previously reported and has unquestionable advantages such as the certainty of diagnosis and the ability to detect a higher number of chromosomal abnormalities, when compared with cell-free fetal DNA.