Figure 7b. RPOC in a 29-year-old woman who experienced acute massive vaginal bleeding 6 weeks after artificial abortion, which was performed due to a fatal anomaly of the fetus. (a) Sagittal T1-weighted image shows a slightly enlarged uterus with multiple serpentine signal voids (arrowheads) in the anterior wall and high-signal-intensity fluid (arrows) in the endometrial cavity. The latter finding is consistent with blood products. (b) Sagittal T2-weighted image shows numerous signal voids with ill-defined borders (arrowheads) in the anterior uterine wall. (c) Sagittal contrast-enhanced T1-weighted image shows ill-defined areas of enhancement (arrowheads) in the anterior uterine wall. However, no enhancing tissue protruding into the uterine cavity is seen. The preliminary diagnosis was arteriovenous malformation (AVM) or placenta increta. Hysterectomy was performed due to continued bleeding and the patient’s refusal to undergo arterial embolization. Surgery revealed a mass in the anterior uterine wall, which was easily peeled away from the myometrium. Thus, the diagnosis of RPOC rather than placenta increta was established. This case illustrates the difficulty of differentiating RPOC from AVM or placenta increta with MR imaging.