Preliminary experience with magnetic resonance imaging in patients with third-trimester bleeding.

Fifteen patients with third-trimester bleeding, in whom transabdominal ultrasound had failed to identify a definitive source of bleeding, underwent magnetic resonance imaging (MRI). Magnetic resonance imaging correctly identified three cases of placenta previa. In four patients, intrauterine blood was identified in hematomas. One hematoma was associated with a previa, two progressed to acute abruptions, and one was associated with a clot at the marginal cord insertion. Blood was seen leading away from the placenta in a case that progressed to an acute abruption. It was also seen in the region of the cervix in two patients with placenta previa. One patient had a normal MRI but had a fresh clot at delivery, which presumably formed after the imaging. In the remaining seven patients, MRI scans were negative and the placentas were normal at delivery. Our preliminary results suggest that MRI is helpful in evaluating patients with unexplained third-trimester bleeding.