The Accuracy of Shear Wave Elastography in the Assessment of Placental Invasion in Women with Placenta Previa

Abstract

Background: Placenta accreta spectrum is a term which describes abnormal invasion of the placenta into the uterine myometrium. The first line in diagnosis is ultrasonography and magnetic resonance imaging may complement the diagnosis. Aim: The aim of the work is to assess the accuracy of shear wave elastography in predication of placental invasion in women with placental previa.Materials and Methods: This is a prospective cohort study which was conducted in Ain Shams University on 50 women with a diagnosis of anterior placenta previa and history of previous cesarean section who were pregnant at 32 weeks or more and were planned for delivery by elective cesarean section. They were subjected to ultrasonography and elastography study and the diagnosis of placenta accreta spectrum was confirmed/ excluded intraoperatively.Results: Placental separation was normal in 36% of cases, delayed in 46 % of cases, partial in 6% of cases only whereas non separation occurred in 12% of cases. elastrgraphy had a sensitivity of 73.7%, specificity of 90.3%, positive predicting value of 82.4% and negative predictive value of 84.8% in diagnosing cases with abnormal placental invasion while sensitivity, specificity positive and negative predictive value of ultrasonography in diagnosing abnormal placental invasion was 89.5%, 96.8%, 94.4% and 93.8% respectively.Conclusion: Elastography is sensitive and specific but inferior to ultrasonography in evaluating women with suspected placenta accreta spectrum but it may be useful in diagnosis of focal invasion.