A retained object tag, and a method of detecting the presence of a retained object or the retained object tag in a medical image. The method can include different steps such as identifying one or more potential sites in the medical image where the retained object or retained object tag may be present. The method can also include analyzing one or more features of the identified potential site against one or more predetermined properties of the retained object or the retained object tag. And the method can include determining whether the identified potential site is a retained object or a retained object tag based in part or more upon the analyzed feature.