The purpose of this study was to compare the value of pelvic ultrasound with color Doppler and magnetic resonance imaging (MRI) in: (1) the diagnosis of placental adhesive disorders (PADs), (2) the definition of the degree of placenta invasiveness, (3) determining the topographic correlation between the diagnostic images and the surgical results. Fifty patients in the third trimester of pregnancy with a diagnosis of placenta previa and at least one previous caesarean section underwent color Doppler ultrasound (US) and MRI. The sonographic and MRI diagnoses were compared with the final pathologic or operative findings. Outcomes at delivery were as follows: normal placenta (n = 38) and PAD (n = 12). MR and US Doppler showed no statistically difference in identiyfing patients with PAD (P = 0.74), while MRI was statistically better than US Doppler in evaluating the depth of placenta infiltration (P < 0.001). MRI accurately characterized the topography of invasion in 12/12 (100%) of the cases, while US accurately characterized the topography of invasion in 9/12 (75%) of the cases. In conclusion, we confirmed that pelvic US is highly reliable to diagnose or exclude the presence of PAD and found MRI to be an excellent tool for the staging and topographic evaluation of PAD.