The value of the first trimester ultrasound in the era of cell free DNA screening.

Objective: To describe the clinically relevant findings detected by the first trimester ultrasound (FTU) and to determine the additional value of the FTU compared to cell free DNA (cfDNA) alone.

Method: Retrospective cohort study of patients undergoing a FTU at a maternal-fetal medicine referral practice. Fetal, gynecologic, and placental findings detected by ultrasound were analyzed with available cfDNA and diagnostic testing results. A subgroup analysis of positive ultrasound findings and cfDNA results was performed to assess the additional benefit of ultrasound evaluation in FT prenatal screening.

Results: There were 1906 FTU between 1 October 2013 and 1 October 2014. CfDNA results were available for 959 (50%) patients. FTU detected: 42 fetal (2.2%), 286 gynecologic (15.0%), and 317 placental (16.6%) findings. CfDNA results were discordant with invasive testing results in 8/61 cases (13%) and with ultrasound findings in 18/42 (42%) cases. There were six false positive and two false negative cfDNA results confirmed by diagnostic testing. Subgroup analysis revealed that cfDNA as the sole method of prenatal screening in the FT would miss 95% of the fetal findings detected with ultrasound.

Conclusion: The comprehensive FTU provides valuable clinical information about fetal and maternal anatomy that cannot be detected with cfDNA alone. © 2016 John Wiley & Sons, Ltd.