Shear Wave Elastography in Assessment of Placental Stiffness of Different Grades of Placental Invasion in Third trimester

Abstract

Background: Placenta accreta spectrum is abnormal invasion of the uterine myometrium by the placenta. Prenatal diagnosis of placenta adherent spectrum is vital to provide effective management. Aim: To assess the placental stiffness in different grades of myometrial invasion. Methods: A case-control study was carried out in Al-Zahraa Hospital, Al-Najaf Governorate, Iraq. The study was carried out between the 1st of December, 2023, and the 30th of September, 2024. Included two groups, Placental-myometrial invasion group A and control group B, each group including 50 participants. All pregnant ladies were examined by grayscale ultrasonography, Doppler study, and 2D shear wave elastography. Results: The mean age of the placental accreta spectrum group was older than that of the pregnant women with normal placentae, with a significant difference of 33.6±5.8 vs. 30.4±6.9 years. The frequency of placental accreta spectrum increases with the increment in parity and gravity and the number of cesarean sections significantly. The median elasticity value was significantly higher among patients with placental accreta spectrum, with a mean ±SD of 7.8±2.4 vs 3.1±0.2 KPa in the control group. There was a highly significant difference in median elasticity values among the placental adhesion grades as median elasticity value increased progressively from normal placenta to accreta, increta, and percreta cases. There was a strong correlation between ultrasound and operative findings, confirming the reliability of ultrasound in diagnosing placental adhesions. Ultrasound was highly effective for diagnosing placenta accreta and percreta, while it shows moderate sensitivity for placenta increta and high specificity across all grades, with a good diagnostic accuracy ranging from 88% for accreta, 93% for increta, and 100% for percreta. Conclusions: Older age, multiparity, multigravida, and prior CS were highly associated with placenta-myometrial invasion. Placental stiffness is significantly higher in pregnancy with placenta accreta spectrum than

pregnancy with  normal placentae. Shear wave elastography can be included with grayscale ultrasound and Doppler study in the assessment of placenta accreta spectrum..