Med. abortion may 29, doc says u.s. is showing retained placental material, 11 weeks later and i need d&c, is this possible? or is it something else?

Possible: I am not an Obstetrician, but I have heard of retained products of conception (retained POC) after elective abortion. It is usually a good idea to evacuate retained POC by D&C, as the material can only be a source for infection or other problems. Retained POCs is not common, but not uncommon either - doctors do the best they can. The oldest POC foun, according to Ripley's BION, is more than 60 yrs

After termination: Retained products of conception and yes, you need to have a d&c if they are still seen on ultrasound.

Yes.: Not only is that possible, it is not uncommon. To prevent a potentially life threatening infection or bleeding/hemorrhage you do need a D&C (dilation and curettage.) You should proceed as soon as possible.