Revisiting ultrasonographic soft markers of aneuploidy: A thoughtful analysis in low-risk and screening naïve Indian antenatal women

This study aimed to assess the prevalence of soft markers on second-trimester sonography in low-risk and screening naïve Indian antenatal women and determine their association with aneuploidy. Soft markers were evaluated through ultrasound, and likelihood ratios (LRs) and modified risk (MR) for aneuploidy were calculated. Pregnant women with a MR >1:250 underwent genetic counseling and invasive testing, whereas those with a lower risk received follow-up. Associations were estimated via Fisher's exact test. A total of 4051 anomaly scans were reviewed, among which 207 (5.1%) women were found to have soft markers (SMs). These included 153 (3.7%) isolated SMs, 43 (1.06%) multiple SMs, and 11 (0.2%) SMs with structural abnormalities. The most common SM was renal pyelectasis. Invasive test uptake increased by 25% among pregnancies with isolated markers and by 55% for those with multiple SMs. A significant association was found between isolated short femur and aneuploidy (p = 0.026), and between multiple SMs and aneuploidy (p = 0.039). Soft markers in low-risk couples can lead to unnecessary invasive testing and anxiety. Genetic counseling is important for discussing relevant factors. Invasive testing for aneuploidies should be based on the modified risk, the presence of multiple SMs, or structural anomalies on ultrasonography.