UROGENITAL Magnetic resonance imaging of clinically stable late pregnancy bleeding: beyond ultrasound Gabriele Masselli & Roberto Brunelli & Tiziana Parasassi & Giuseppina Perrone & Gianfranco Gualdi Received: 28 December 2010 / Accepted: 23 February 2011 # European Society of Radiology 2011 Abstract Objectives To compare the accuracy of magnetic resonance (MRI) and colour Doppler-ultrasound (US) in the diagnosis of late pregnancy bleeding and to assess the accuracy of the different MR sequences in visualizing the origin of haemorrhage. Methods 42 patients in the third trimester of pregnancy underwent to US and MRI for the evaluation of painless vaginal bleeding. Multiplanar HASTE, True Fisp, 3D T1 GRE and sagittal DWI sequences were acquired. Two radiologists, blinded to the results of US, reviewed each case, resolving by consensus any discrepancy. Reference standards were surgical and pathological findings. Results The reference standards identified 22 placenta previa, 11 placental abruptions (1 coincident with a placental chorioangioma), 1 thrombohaematoma and 1 fibroma with haemorrhagic degeneration. MRI identified correctly all these condition with an interobserver agree- ment of 0.955. DWI and T1 weighted sequences were statistically superior to Haste and True Fisp sequences in detecting the cause of bleeding (p <.001). US had 6 false negatives and 2 false positive results, its diagnostic accuracy resulting lower than MRI (p =.001). Conclusions MRI accurately evaluates pregnancy bleeding with an excellent interobserver agreement and can grant new and additional data when US is negative. Keywords Late pregnancy bleeding . Magnetic resonance . Obstetric hemorrhage . Placental abnormalities . Placenta hematoma Introduction Obstetric haemorrhage is still one of the leading causes of maternal mortality and morbidity and causes many diag- nostic and management dilemmas for the obstetrician [1]. Of note, optimal management of late pregnancy bleeding relies on an accurate identification of the cause and a specific and timely intervention [2]. Placental abnormalities are major contributors to obstetric haemorrhage [3]; common abnormalities in- clude placenta previa, placental abruption, placenta adhesive disorders (accreta, increta, percreta) and vasa previa [4]. Ultrasound (US) is the mainstay of fetal and placental imaging in the antepartum period [5]; however, despite constant improvements in US technology over last years, the diagnostic US sensitivity for detecting bleeding is still low and has not significantly improved [6]. Magnetic resonance imaging (MRI/MR) is increas- ingly considered after negative US in several maternal disease during pregnancy [7–11]. MRI offers multiplanar imaging capabilities, a wide field of view, a high soft G. Masselli (*) : G. Gualdi Radiology Dea Department, Umberto I Hospital, Sapienza University, Viale del Policlinico 155, 00161 Rome, Italy e-mail: gabrielemasselli@libero.it R. Brunelli : G. Perrone Department of Gynecology and Obstetrics, Umberto I Hospital, Sapienza University, Viale del Policlinico 155, 00161 Rome, Italy T. Parasassi Institute of Neurobiology and Molecular Medicine, National Research Council, Via del Fosso del Fiorano 64, Viale del Policlinico 155, 00143 Rome, Italy Eur Radiol DOI 10.1007/s00330-011-2120-8