In acute cases, with a large amount of blood loss, patients may present with anemia or low blood pressure. However, aside from the<unk>  itself, many patients may present with few symptoms. Often, the first approach is to use endoscopy to look for obvious signs of a bleed. In cases where the source of the bleed is unclear, but<unk>  is present, an upper endoscopy is recommended, to try to ascertain the source of the bleed. Lower gastrointestinal bleeding sources usually present with hematochezia or frank blood. A test with poor sensitivity/specificity that may detect the source of bleeding is the tagged red blood cell scan. This is especially used for slow bleeding (0.5 ml/min), mesenteric angiogram ± embolization is the gold standard. Colonoscopy is often first line, however.<unk>  versus hematochezia Bleeds that originate from the lower gastrointestinal 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 more proximal source (such as the small intestine), or bleeding from a lower source that occurs slowly enough to allow for enzymatic breakdown, is associated with<unk> . For this reason,<unk>  is often associated with blood in the stomach or duodenum (upper gastrointestinal bleeding), 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<unk> . One often-stated rule of thumb is that<unk>  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.
Melena
Riken
Lentigo
Atagi
Weleda
Meth mouth
Puskesmas
Stoccareddo