Placental elasticity in trisomy 21: prenatal assessment with shear-wave elastography

To quantitatively examine placental tissue elasticity in Trisomy 21 (T21) pregnancies using shear wave elastography (SWE) and to evaluate the potential contribution of placental SWE measurements in predicting T21 fetuses.

This prospective case-control study was conducted at tertiary centers between January 2022 and January 2024. The study included 30 pregnant women who underwent invasive prenatal diagnostic testing and were found to have T21, along with 30 pregnant women with a normal karyotype. Central placental elasticity measurements were performed from the middle of the thickest part of the placenta, avoiding vascular areas and lacunae, and peripheral measurements were performed two centimeter (cm) medial to the lateral border of the placenta.

The mean gestational week at measurement was 16 ± 2 weeks. Peripheral placental SWE velocity was significantly higher in the T21 group (7.4 ± 3.7 kPa vs. 4.8 ± 3.6 kPa, p=0.004). Similarly, central placental SWE velocity was also significantly higher in the T21 group (6.5 ± 2.1 kPa vs. 4.1 ± 2.6 kPa, p<0.001). In predicting T21, central placental SWE velocity had 76.7 % sensitivity and 73.3 % specificity with a cut-off value of ≥4.35 kPa (p<0.001), and peripheral had 70 % sensitivity and 66.7 % specificity with a cut-off value of ≥4.65 kPa (p=0.004). When central placental SWE velocity was ≥4.35 kPa, the risk of T21 was increased 6.64-fold, even after adjusting for maternal age, which is a well-known risk factor for T21.

Placental stiffness was significantly higher in T21 in both central and peripheral areas. Placental elasticity, especially in the central part, may be a potential marker for T21.