Placenta accreta: imaging by gray-scale and contrast-enhanced color Doppler sonography and magnetic resonance imaging.

Antepartum diagnosis of placenta accreta on the scarred myometrium of the isthmus uteri after previous cesarean section was made in 2 pregnancies. Antepartum sonographic examination revealed abnormal bulging of placental tissue toward the bladder cavity and arcuate arteries within the bladder wall. Magnetic resonance imaging revealed the depth and extent of placental invasion into the myometrium of the isthmus and the bladder muscular layer. Low-resistance pulsatile intervillous flow was recorded within the placenta in 1 case. Both magnetic resonance imaging and contrast-enhanced color Doppler sonography were informative in the other of these cases, in which the patient was conservatively managed during pregnancy and after delivery.