Retained products of conception (RPOC) refers to tissue that remains in your uterus after a pregnancy ends. The tissue is usually from the placenta, which is an organ that develops in your uterus during pregnancy. However, this tissue can also be fetal tissue. Ultrasound is typically the first-line investigation in suspected retained products of conception - a variable amount of echogenic or heterogeneous material within the endometrial cavity; in some instances, this may present as an endometrial or intrauterine mass; presence of vascularity within the endometrial echogenic material supports the diagnosis but the absence of color Doppler flow has a low negative predictive value because retained products of conception may be avascular; calcification may be present.