Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include vomiting red blood, vomiting black blood, bloody stool, or black stool. Small amounts of bleeding over a long time may cause iron-deficiency anemia resulting in feeling tired or heart-related chest pain. Other symptoms may include abdominal pain, shortness of breath, pale skin, or passing out. Sometimes in those with small amounts of bleeding no symptoms may be present. Bleeding is typically divided into two main types: upper gastrointestinal bleeding and lower gastrointestinal bleeding. Causes of upper GI bleeds include: peptic ulcer disease, esophageal varices due to liver cirrhosis and cancer, among others. Causes of lower GI bleeds include: hemorrhoids, cancer, and inflammatory bowel disease among others. Diagnosis typically begins with a medical history and physical examination, along with blood tests. Small amounts of bleeding may be detected by fecal occult blood test. Endoscopy of the lower and upper gastrointestinal tract may locate the area of bleeding. Medical imaging may be useful in cases that are not clear. Initial treatment focuses on resuscitation which may include intravenous fluids and blood transfusions. Often blood transfusions are not recommended unless the hemoglobin is less than 70 or 80 g/L. Treatment with proton pump inhibitors, octreotide, and antibiotics may be considered in certain cases. If other measures are not effective, an esophageal balloon may be attempted in those with presumed esophageal varices. Endoscopy of the esophagus, stomach, and duodenum or endoscopy of the large bowel are generally recommended within 24 hours and may allow treatment as well as diagnosis. An upper GI bleed is more common than lower GI bleed. An upper GI bleed occurs in 50 to 150 per 100,000 adults per year. A lower GI bleed is estimated to occur in 20 to 30 per 100,000 per year. It results in about 300,000 hospital admissions a year in the United States. Risk of death from a GI bleed is between 5% and 30%. Risk of bleeding is more common in males and increases with age. Classification Gastrointestinal bleeding can be roughly divided into two clinical syndromes: upper gastrointestinal bleeding and lower gastrointestinal bleeding. About 2/3 of all GI bleeds are from upper sources and 1/3 from lower sources. Common causes of gastrointestinal bleeding include infections,