Impact of introducing cell-free DNA screening into clinical care on first trimester ultrasound.

Objective: First-trimester ultrasound is an important component of prenatal care. We investigated the impact of introducing cell-free DNA (cfDNA) aneuploidy screening into routine care, on performance of first-trimester ultrasound.

Methods: Retrospective study of patients who had prenatal care at a tertiary referral center. We compared the performance of any first-trimester ultrasound between three different aneuploidy screening protocols, used consecutively during the study period: (1) combined first-trimester screening (FTS); (2) FTS and cfDNA offered together; (3) patients requested to choose between FTS and cfDNA. Secondary outcomes included performance of nuchal translucency (NT), aneuploidy screens and diagnostic genetic procedures.

Results: The number of patients undergoing first-trimester ultrasound remained similar with the second protocol but decreased in the third (68.7% vs. 40.9%, OR 0.32, 95% CI 0.25-0.4, p < 0.001). Diagnostic procedures decreased between protocol 1 and 2 (7.6% vs. 4.4%, OR 0.59, 95% CI 0.37-0.93, p = 0.02) while NT scans decreased between protocol 2 and 3 (6.8% vs. 1.3%, OR 0.18, 95% CI 0.09-0.4, p < 0.001). The rate of FTS decreased over the study period and less women had cfDNA when they had to choose one method (p < 0.001).

Conclusions: Introducing cfDNA screening as an alternative to FTS, resulted in fewer patients receiving ultrasound in the first-trimester.