Abnormal placentation: the role of MRI in diagnosis and therapeutic planning

To evaluate the role of magnetic resonance imaging (MRI) for diagnosis and therapeutic planning in patients with abnormal placentation (AP).

Overall, 168 consecutive patients with suspected placenta previa and AP were referred for MRI before caesarean section (CS). The ability of MRI to properly detect and assess abnormal placentation was correlated with findings at CS, which were considered the reference standard diagnostic tool. For each patient, MRI was used to determine whether the AP was suitable for complete/incomplete delivery, hysterectomy, or conservative treatment. Treatment planning with MRI was prospectively compared with the actual treatment that had been carried out in each patient decided at CS.

Placenta previa was detected at MRI in 63 patients and AP in 105 patients; 16 patients had false-positive MRI findings, and three had false-negative findings. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI compared to findings at CS were 88.9% (149 of 168), 96.7% (89 of 92), 78.9% (60 of 76), 84.8% (89 of 105), and 95.2% (60 of 63), respectively. Treatment planning could be correctly made on the basis of MRI with accuracy, sensitivity, specificity, PPV, and NPV of 97%, 100%, 92.6%, 95.2%, and 100%, respectively.

MRI offers high diagnostic accuracy in the detection of AP, and it may be helpful in the detailed planning of treatment.