Source:http://linkedlifedata.com/resource/umls/id/C0018932
NCI: The passage of fresh blood from the anus. The blood is usually seen in the stools. The most common cause is lower gastrointestinal tract hemorrhage.,MSH: The passage of bright red blood from the rectum. The blood may or may not be mixed with formed stool in the form of blood, blood clots, bloody stool or diarrhea.