Sensitivity and specificity of echography in the diagnosis of placental accretism in patients with diagnosis of placenta praevia

Objective: Placenta accrete (PA) is a lack of decidual area between the placenta and miometrium, thus the trophoblast is directly facing the miometrium. The 88% of placenta accreta is associated with placenta praevia and it is the cause of 33-50% of all peripartum hysterectomies. The higher incidence of placenta praevia/accreta is due to an increased number of caesarean sections (CS), with an 8 times increased risk with two previous CS and a 2 time increased risk with one previous CS. Ultrasound (US) and color Doppler are used to diagnose PA. A correct diagnosis of placental accretism can improve maternal-fetal prognosis through an adequate planning of the delivery. The aim of the present study was to establish our echographic accuracy in the diagnosis of placental accretism. Methods: From January 2011 until December 2012 we prospectively analyzed 188 cases with a diagnosis of placenta praevia. We searched for the echographic criteria of placental accretism by 2D and 3D US and color-doppler after 24th weeks of gestation. Confirmation of placental accretism was histological or clinical (incomplete delivery of placenta and/or visible areas of accretism). Results: There were 28 cases of PA, 57% of which histologically diagnosed. US and color Doppler detected 78% of them, with a specificity of 99%. Sensitivity and specificity improved through the years: 76% (13/17) and 100% (80/80) respectively in 2011 and 82% (9/11) and 97% (78/80) respectively in 2012. In 2011, 11/17 (65%) diagnosed PA had an hysterectomy after CS and in 2012 5/11 (45%). Conclusions: We confirmed that echography is a good methodology in the diagnosis of placental accretism. Indeed, the knowledge of PA allowed planning of time and site of delivery thus improving outcomes.