Study of Use of Shear Wave Elastography in Placental Dysfunction by Comparison of Elasticity Values in Normal and Pre-eclamptic Pregnancies

Abstract

Background: It has been believed that placental stiffness varies between normal and pre-eclamptic pregnancies. In order to appreciate this difference, Share Wave Elastography (SWE) of the placenta was done to assess the degree of placental stiffness. Objective: The aim of the current study was to evaluate the utility of SWE in detection of preeclampsia and correlate the degree of placental stiffness with severity of pre-eclampsia and with perinatal outcome. Patients and methods: A total of 76 pregnant females in second or third trimester were enrolled in the present study. Half of them (38 females) had normal pregnancy with no history of medical disease and the second half (38 females) had pregnancy complicated by pre-eclampsia. SWE was used for all cases. Results: In pre-eclamptic placentas, the mean stiffness values were significantly higher across all regions and layers compared to healthy controls. The central placental region showed the greatest disparity. A moderate correlation was also found between the severity of pre-eclampsia and SWE data. Maximum diagnostic accuracy was achieved with a cutoff of 18.47 kPa for the central placenta (area under the curve: 0.97; confidence interval: 0.88-1; sensitivity: 94.7%; specificity: 94.7%; PPV 92.3; and accuracy: 94.7%). Regarding other obstetric and Doppler findings there was a significant decrease in measured abdominal circumference AC and femur length FL among preeclamptic pregnancies compared with the control group, together with abnormal Doppler indices with highly statistical significant increase of resistive index of umbilical artery and significant decrease of resistive index of middle cerebral artery among preeclampsia patients compared to the control group. Conclusion: Difference in placental stiffness between healthy and pre-eclamptic pregnancies can be assessed using SWE, and it can be used for mentoring early perinatal outcome together with routine obstetric and Doppler ultrasound study.