[Placenta accreta: can prenatal diagnosis be performed? Ultrasound and MRI interests. About 27 cases]

To list ultrasonography signs identified when a placenta accreta is suspected. Secondary objectives are to analyze the relevance of diagnosis with ultrasonography and magnetic resonance imaging, and to know diagnosis circumstances in order to identify main risk factors.

We present a monocentric retrospective study. All the cases of placentas accreta, observed from 2005 to 2010 at Lille University Hospital (France), have been included.

Twenty-seven patients had a placenta accreta during this period. There was an antenatal suspicion for 22 cases and 21 were confirmed after delivery. Six cases were discovered per-partum. Diagnosis was suspected after metrorrhagia for 41% of women. In case of antenatal diagnosis, 100% of the patients had an anterior placenta praevia and an uterine scare. Fifty percent of the placentas accreta diagnosed per-partum were posterior. The most frequently ultrasonography signs are "intra-placental lacuna" (85.7%), "abnormal vascularization" (71.4%), "loss of normal hypoechoic retroplacental myometrial zone" (66.7%), "irregularity of the vesical wall" (66.7%). Sensibility of ultrasonography screening is 78%. Twenty-one magnetic resonance imaging examinations executed secondarily confirmed the diagnosis in 66.7% of the cases.

Ultrasonography is a relevant exam for the diagnosis of placenta accreta. Posterior placenta should not be forsaken. Anterior placenta praevia in multiparous patients with a uterine scare should be a warning.