Enhanced myometrial vascularity on MRI in a patient with retained products of conception.

Secondary postpartum hemorrhage (PPH), sometimes referred to as secondary postpregnancy hemorrhage, is a potentially serious complication that arises between 24 hours and 12 weeks after delivery. Retained products of conception (RPOC) and subinvolution of the placental site are common causes, but uterine vascular anomalies such as arteriovenous malformations (AVMs) can present with similar clinical imaging findings, creating diagnostic uncertainty. Enhanced myometrial vascularity (EMV) has recently been recognized as a postpartum vascular finding that may mimic AVMs on ultrasound and magnetic resonance imaging (MRI). Because true congenital AVMs are rare, most AVM-like lesions encountered in the postpartum period likely represent acquired vascular changes or EMV, making accurate diagnosis vital for appropriate and fertility-preserving management. We present the case of a 34-year-old gravida 5 para 3 patient who developed persistent heavy vaginal bleeding following early pregnancy loss. Serial ultrasounds demonstrated a thickened, hypervascular endometrium with extension into the myometrium, raising concern for either RPOC or uterine AVM. Despite declining serum β-hCG levels, her symptoms persisted. MRI performed nearly two months after pregnancy loss revealed intrauterine enhancing material consistent with RPOC and associated EMV, favoring a diagnosis of EMV over AVM. The patient subsequently underwent successful hysteroscopic dilation and curettage, with pathology confirming RPOC and resolution of symptoms. This case highlights the diagnostic challenge and importance of differentiating EMV from uterine AVM in the evaluation of secondary PPH to avoid unnecessary invasive treatments such as embolization or hysterectomy.