Role of Placental Vascularization Indices and Shear Wave Elastography in Fetal Growth Restriction.

Objective: To evaluate the role of placental vascularisation indices using 3D-Power Doppler and placental elasticity using Shear Wave Elastography (SWE) in Fetal Growth Restricted (FGR) pregnancies and to assess their correlation with perinatal outcomes.

Methods: This prospective case-control study was conducted from June 2018-2020. Thirty women with FGR and thirty controls (24-36 weeks) underwent grayscale and Doppler ultrasonography followed by measurement of vascularisation indices and SWE from the central and peripheral parts of fetal and maternal surfaces of the placenta. Participants were followed till delivery and perinatal outcomes were noted.

Results: Vascularisation indices were significantly reduced among FGR vs. controls: Vascularisation Index (VI): 20.90 ± 5.46 vs. 31.49 ± 3.89, Flow Index (FI): 26.29 ± 1.70 vs. 30.85 ± 2.02, Vascularisation- Flow Index (VFI): 7.06 ± 2.42 vs. 12.37 ± 2.43,  < 0.001. The mean placental SWE (17.36 ± 1.50 kPa) in FGR pregnancies was significantly higher as compared to controls (4.14 ± 1.14 kPa),  < 0.001. Neonatal polycythaemia and hyperbilirubinemia were significantly increased in FGR pregnancies with higher SWE value. Receiver operating characteristic curve-based cut-off of VI for intensive care requirement was 23.0 (sensitivity: 75%, specificity: 71%) and for tachypnea was 22.8 (73% sensitivity and specificity). The cut-off of FI for low birth weight was 25.7 (sensitivity: 69.6%, specificity: 71.4%).

Conclusion: This study demonstrates that increased placental stiffness and reduced vascularisation in FGR indicate possible placental pathology. Both modalities help in predicting perinatal complications. Hence, vascularisation indices and SWE reflect the extent of placental insufficiency and can be useful adjuncts in diagnosis.