Placental elastography in second trimester preeclampsia prediction: A prospective study

Abstract

Objective: The aim of the study was to evaluate the diagnostic potential of placental shear wave elastography in predicting preeclampsia at 16 to 20 weeks of gestation.

Materials and methods: A total of 230 pregnant women between 16 and 20 weeks of gestation were observed for the study. These women underwent shear wave elastography ElastPQ (Philips Healthcare, Bothell, Washington, USA) of the placenta. The mean value of placental shear modulus was obtained for each participant. These participants were followed up for the development of preeclampsia and were divided into two groups; group A included those who developed preeclampsia and group B included those who remained normotensive until delivery. The elasticity values of the two groups were compared, and the ROC curve was drawn to obtain the best cut-off value that would predict the onset of preeclampsia.

Results: Placental shear modulus varied from 1.03 kPa to 7.4 kPa at 16 to 20 weeks of gestation with an average of 2.74 ± 0.87 kPa. There was a statistically significant difference in the mean value of elasticity between two groups, being 4.61 kPa in group A and 2.51 kPa in group B. Maximum diagnostic accuracy was obtained at 2.9667 kPa with area under the curve 0.970, sensitivity 92%, specificity 91.71%, positive predictive value 57.5% and negative predictive value 98.9%.

Conclusion: Stiffness of placenta, quantitatively measured by SWE at 16 to 20 weeks of gestation, is higher in the women who develop preeclampsia and hence may be used for predicting preeclampsia.

Keywords: ElastPQ; Shear wave elastography; gestational hypertension; pregnancy.

Figure 1.

ElastPQ shear wave elastography images of a 25-year-old pregnant woman at 17 weeks of gestation. (a) ROI box placed near the right edge of placenta gives an elasticity value of 1.97 kPa. (b) ROI box placed at the centre of placenta gives an elasticity value of 2.59 kPa. (c) ROI box placed near the left edge of placenta gives an elasticity value of 1.0 kPa. This woman remained normotensive throughout the pregnancy.

Figure 2.

ElastPQ shear wave elastography images of a 27-year-old pregnant woman at 19 weeks of gestation. (a) ROI box is placed near the right edge of placenta where the elasticity value is 5.54 kPa. (b) ROI box is placed at the centre of placenta where the elasticity value is 3.06 kPa. (c) ROI box is placed near the left edge of placenta where the elasticity value is 4.75 kPa. This woman developed preeclampsia later in pregnancy.

Figure 3.

Distribution of elasticity values of the two groups at three different sites of placenta.

Figure 4.

Receiver operating characteristic curve for prediction of preeclampsia based on ElastPQ shear wave elastographic values. The cut-off value and area under curve were 2.96 kPa and 0.97, respectively.