Source:http://linkedlifedata.com/resource/umls/id/C0032046
NCI: A condition in which the placenta is implanted in the lower part of the uterus. --2003,MSH: Abnormal placentation in which the PLACENTA implants in the lower segment of the UTERUS (the zone of dilation) and may cover part or all of the opening of the CERVIX. It is often associated with serious antepartum bleeding and PREMATURE LABOR.