The performance of hyperadherence markers in anterior placenta praevia overlying the Caesarean scar

To assess the ultrasound (US) impact in diagnosing placenta accreta (PA) in patients with anterior placenta praevia localization, overlying a Caesarean scar.

This is a prospective study between January 2016 and December 2017 that included patients with Caesarean scar and placenta praevia in the third trimester of pregnancy. By means of two-dimensional (2D) grayscale and color Doppler, we investigated the presence of the following US markers for placental invasion: intraplacental lacunae, abnormal blood vessels at the myometrium-bladder interface, thinning of the hyperechogenic uterine serosa-bladder wall interface, loss of normal hypoechoic retroplacental myometrial space. Definitive diagnosis was made at delivery. The US findings were correlated with intraoperative and histopathological (HP) evaluations.

We found 46 cases with anterior placenta praevia overlying a Caesarean scar. Twelve patients presented US criteria for PA. The confirmation was obtained (by means of intraoperative and/or HP features) in 11 of them. The US evaluation with all markers yields a sensitivity of 100% for PA detection. Among the US markers, the association of abnormal blood vessels at the myometrium-bladder interface and the intraplacental lacunae had the highest statistical correlation in the antenatal diagnosis of PA.

Our study suggests that the antenatal US is a useful tool in predicting PA in high-risk patients. Special attention should be given to the presence of intraplacental lacunae and abnormal myometrial vessels in cases where the placental insertion overlaps a uterine scar for best identification of PA high-risk cases.