Hematochezia

Hematochezia Hematochezia is the passage of fresh blood through the anus, usually in or with stools. 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 the latter rectal bleeding is not associated with defaecation. Instead, it is associated with expulsion of fresh bright red blood without stools. The phrase bright red blood per rectum (BRBPR) 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, hematochezia 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. Hematochezia can be due to upper gastrointestinal bleeding. However, as the blood from such a bleed is usually chemically modified by action of acid and enzymes, it presents more commonly as melena. Hematochezia from an upper gastrointestinal source is an ominous sign, as it suggests a very significant bleed which is more likely to be life threatening. Beeturia can cause red colored feces after eating beets because of insufficient metabolism of a red pigment, and is a differential sign that may be mistaken as hematochezia. Consumption of dragon fruit or pitaya may also cause red discoloration of the stool and sometimes the urine.This too, is a differential sign that is sometimes mistaken for hematochezia.

Melena In medicine, melena or melæna refers to the black, "tarry" feces that are associated with gastrointestinal hemorrhage. The black color is caused by the hemoglobin in the blood being altered by digestive chemicals and intestinal bacteria. Iron supplements may cause a grayish-black stool that should be distinguished from the black, tarlike stool that occurs from bleeding ulcer. Causes The most common cause of melena is peptic ulcer disease. Any other cause of bleeding from the upper gastrointestinal tract, or even the ascending colon, can also cause melena. Melena may also be a sign of drug overdose if a patient is taking anticoagulants, such as warfarin. It is also caused by tumors, especially malignant tumors affecting the esophagus, more commonly the stomach & less commonly the small intestine due to their bleeding surface. However,the most prominent and helpful sign in these cases of malignant tumors is haematemesis. It may also accompany hemorrhagic blood diseases (e.g. purpura & hemophilia). Other medical causes of melena include bleeding ulcers, gastritis, esophageal varices, and Meckel's diverticulum Causes of "false" melena include iron supplements, Pepto-Bismol, Maalox, and lead, blood swallowed as a result of a nose bleed (epistaxis), and blood ingested as part of the diet, as with consumption of black pudding (blood sausage), or with the traditional African Maasai diet, which includes much blood drained from cattle. Melena is often a medical emergency as it arises from a significant amount of bleeding. Urgent care is required to rule out serious causes and prevent potentially life-threatening emergencies. A less serious, self-limiting case of melena can occur in newborns two to three days after delivery, due to swallowed maternal blood. Melena vs. hematochezia Bleeds that originate from the lower GI tract (such as the sigmoid colon and rectum) are generally associated with the passage of bright red blood, or hematochezia, particularly when brisk. Only blood that originates from a high source (such as the small intestine), or bleeding from a lower source that occurs slowly enough to allow for enzymatic breakdown is associated with melena. For this reason, melena is often

associated with blood in the stomach or duodenum for example by a peptic ulcer. A rough estimate is that it takes about 14 hours for blood to be broken down within the intestinal lumen; therefore if transit time is less than 14 hours the patient will have hematochezia, and if greater than 14 hours the patient will exhibit melena. One often-stated rule of thumb is that melena only occurs if the source of bleeding is above the ligament of Treitz although, as noted below, exceptions occur with enough frequency to render it unreliable.