persistent low levels of beta-hcg: a pitfall in diagnosis of retained product of conception

Persistent low level of beta-hcg (pll) is defined as rising hcg level no more than two-fold over a three months period. almost many types of pll can lead to the wrong diagnosis. here, we presented two cases of the retained product of conception (rpoc) with persistent low levels of beta-hcg. both cases were presented with persistent low levels of beta-hcg and abnormal uterine bleeding since first-trimester pregnancy termination. ultrasonography revealed a vascular mass with extension from the endometrial cavity to myometrium imitating gestational trophoblastic disease (gtd) or arteriovenous malformation (avm). the final pathologies of both cases were retained product of conception. imaging features of rpoc can closely imitate those of an avm or gtn; so, hysteroscopy is one of the best non-invasive procedures which may be helpful in diagnosis and selection of appropriate treatment especially in young patients who desire to preserve their fertility.