Assessment of total placenta previa by magnetic resonance imaging and ultrasonography to detect placenta accreta and its variants

Abstract

Objective: To evaluate the importance of ultrasonography (US) and magnetic resonance imaging (MRI) in detecting placental adherence defects. Material and methods: Patients diagnozed with total placenta previa (n=40) in whom hysterectomy was performed due to placental adherence defects (n=20) or in whom the placenta detached spontaneously after a Cesarean delivery (n=20) were included into the study between June 2008 and January 2011, at the Department of Obstetrics and Gynecology, Ege University (Izmir, Turkey). Gray-scale US was used to check for any placental lacunae, sub-placental sonolucent spaces or a placental mass invading the vesicouterine plane and bladder. Intra-placental lacunar turbulent blood flow and an increase in vascularization in the vesicouterine plane were evaluated with color Doppler mode. Subsequently, all patients had MRI and the results were compared with the histopathologic examinations. Results: The sensitivity of MRI for diagnosis of placental adherence defects before the operation was 95%, with a specificity of 95%. In the presence of at least one diagnostic criterion, the sensitivity and specificity of US were 87.5% and 100% respectively, while the sensitivity of color Doppler US was 62.5% with a specificity of 100%. Conclusions: Currently, MRI appears to be the gold standard for the diagnosis of placenta accreta. None of the ultrasonographic criteria is solely sufficient to diagnose placental adherence defects, however, they assist in the diagnostic process.