Understanding obstetrical soft markers: Significance and implications in 2025

Over the past two decades, prenatal screening options have advanced considerably. Ultrasound soft markers and serum screening have long served as the foundation for non-invasive aneuploidy risk assessment. The advent of cell-free DNA (cfDNA) testing has further enhanced the ability to screen for common aneuploidies, offering the most accurate single screening method for trisomies 21, 18, and 13. The Society of Obstetricians and Gynaecologists of Canada (SOGC) first published guidelines on soft markers in 2005, with subsequent updates in 2017 and 2024, reflecting ongoing changes in screening recommendations. Consequently, the role of ultrasound soft markers has shifted. Many isolated soft markers are no longer considered statistically significant. This article will review recent developments and their relevance to current sonographic practice, emphasizing the continued importance of soft markers in identifying chromosomal abnormalities.