hematochezia

Hematochezia is a form of blood in stool, in which fresh blood passes through the anus while defecating. It differs from melena, which commonly refers to blood in stool originating from upper gastrointestinal bleeding (UGIB). The term derives from Greek αἷμα ("blood") and χέζειν ("to defaecate"). Hematochezia is commonly associated with lower gastrointestinal bleeding, but may also occur from a brisk upper gastrointestinal bleed. The difference between hematochezia and rectorrhagia is that rectal bleeding is not associated with defecation; instead, it is associated with expulsion of fresh bright red blood without stools. The phrase bright red blood per rectum is associated with hematochezia and rectorrhagia.

==Causes== In adults, most common causes are hemorrhoids and diverticulosis, both of which are relatively benign; however, it can also be caused by colorectal cancer, which is potentially fatal. In a newborn infant, haematochezia may be the result of swallowed maternal blood at the time of delivery, but can also be an initial symptom of necrotizing enterocolitis, a serious condition affecting premature infants. In babies, hematochezia in conjunction with abdominal pain is associated with intussusception. In adolescents and young adults, inflammatory bowel disease, particularly ulcerative colitis, is a serious cause of hematochezia that must be considered and excluded.