(109) Prenatal diagnostic testing trends in the era of cell-free DNA screening

Objective: According to the American College of Obstetrics and Gynecology, all pregnant patients should be offered testing for fetal aneuploidy. Cell-free DNA screening became available at our institution in 2012. We investigated the trends of diagnostic testing, diagnostic yield, and indications for procedure in the era of cell-free DNA.

Study Design: In this observational retrospective study, all invasive prenatal procedures from 2010 to 2022 were evaluated at a single institution. Indication for procedure was determined (advanced maternal age alone, ultrasound findings, abnormal prenatal screen, single gene testing). Results of diagnostic testing were reviewed and stratified by result and type of genetic abnormality. Categorical variables were assessed using X² or Fishers Exact test as appropriate and comparisons of column proportions; continuous variables were analyzed with Wilcoxon rank-sum test.

Results: A total of 1262 invasive procedures were performed in the study period, with 888 (70.4%) amniocentesis procedures and 374 (29.6%) chorionic villus sampling procedures (Figure 1). There was a significant decline in total procedures over time (p < .001). Fifty one percent of patients had prenatal genetic screening, with 28.2% of patients having diagnostic testing for abnormal prenatal screen. In 2017, cell free DNA analysis surpassed analyte testing as the primary genetic screening modality. Overtime, percentage of abnormal diagnostic result increased (Fig 1). There was a significant change in indication over time; advanced maternal age alone declined from 45% to 5.6% during the study period(p < .001).

Conclusion: Performance of invasive testing for prenatal chromosomal disorders has dramatically decreased since cell-free DNA testing became universally available. This has resulted in a shift in indication for diagnostic testing and higher diagnostic yield.