First Trimester Ultrasound Soft Markers in a Fetus: Genetic Associations and Diagnostic Implications

Advances in prenatal screening have significantly improved the early detection of fetal anomalies and chromosomal abnormalities. Among these, first-trimester soft markers have emerged as valuable indicators of potential adverse outcomes. This review explores the clinical relevance of key markers—including increased nuchal translucency (NT), nasal bone hypoplasia, tricuspid regurgitation, aberrant right subclavian artery, and abnormal ductus venosus flow—and their associations with aneuploidy, structural malformations, and pregnancy complications such as preeclampsia and fetal growth restriction. We emphasize the importance of interpreting soft markers within a comprehensive clinical context, rather than in isolation, and examine their underlying pathophysiological mechanisms and associated statistical risks. Particular attention is given to the integration of soft marker findings with advanced screening techniques, including cell-free DNA (cfDNA) testing and maternal serum biochemistry, to improve diagnostic accuracy. In addition, we review current recommendations for clinical management, such as the use of follow-up diagnostic procedures like chorionic villus sampling or amniocentesis, and the role of multidisciplinary counselling in high-risk pregnancies. Future research should aim to validate novel soft markers and promote the standardization of screening protocols to enhance maternal and fetal outcomes.