Gastrointestinal bleeding indicates underlying pathology in either the upper or lower gastrointestinal (GI) tract. Hematemesis Hematemesis Vomiting of blood that is either fresh bright red, or older 'coffee-ground' in character. It generally indicates bleeding of the upper gastrointestinal tract. Mallory-Weiss Syndrome (Mallory-Weiss Tear) ( vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia red blood or “coffee-ground” material) and melena (black, tarry stool) usually indicate upper GI bleeding proximal to the suspensory ligament Suspensory ligament Ovaries: Anatomy of the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy, also called the ligament of Treitz. Peptic ulcer Peptic ulcer Peptic ulcer disease (PUD) refers to the full-thickness ulcerations of duodenal or gastric mucosa. The ulcerations form when exposure to acid and digestive enzymes overcomes mucosal defense mechanisms. The most common etiologies include Helicobacter pylori (H. pylori) infection and prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs). Peptic Ulcer Disease disease ( PUD PUD Peptic ulcer disease (PUD) refers to the full-thickness ulcerations of duodenal or gastric mucosa. The ulcerations form when exposure to acid and digestive enzymes overcomes mucosal defense mechanisms. The most common etiologies include Helicobacter pylori (H. pylori) infection and prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs). Peptic Ulcer Disease) is the most common cause of upper GI bleeding. Hematochezia (red blood in the stool) is most often associated with lower GI bleeding (although it infrequently occurs with massive upper GI bleeding that is typically associated with hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension). Lower GI bleeding can be from diverticular disease Diverticular disease Diverticula are protrusions of the bowel wall occurring most commonly in the colon. The condition of having diverticula (called diverticulosis) is mostly asymptomatic. These diverticula can become symptomatic, however, when associated with diseases. Diverticulitis is the inflammation of diverticula, often presenting with lower abdominal pain and changes in bowel habits. Diverticular Disease, angiodysplasia, polyps or tumors, inflammatory bowel disease, or internal hemorrhoids Hemorrhoids Hemorrhoids are normal vascular cushions in the anal canal composed of dilated vascular tissue, smooth muscle, and connective tissue. They do not cause issues unless they are enlarged, inflamed, thrombosed, or prolapsed. Patients often present with rectal bleeding of bright red blood, or they may have pain, perianal pruritus, or a palpable mass. Hemorrhoids. Diagnosis is made by clinical history and physical exam, followed by upper and/or lower GI endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD). The source of the bleeding can usually be identified and treated with endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD).
Last updated: Dec 1, 2025
Upper gastrointestinal bleed (proximal to the ligament of Treitz):
Lower GIB (distal to the ligament of Treitz):

Thrombosed external hemorrhoid with prolapsing internal hemorrhoid
Image: “Circular perianal thrombosis” by Rohde et al; licensee BioMed Central Ltd.. License: CC BY 2.0Diagnosis and management of GIB tend to go hand-in-hand and will vary depending on the hemodynamic stability of the patient.

Algorithm for evaluating a hemodynamically unstable patient: The first step requires attempting to stabilize the patient before pursuing workup. The patient’s response will then determine whether the patient should go straight to angiography for diagnosis and treatment, or endoscopy.
Image by Lecturio.
Diagnostic algorithm for LGIB in a hemodynamically stable patient: Colonoscopy is the preferred 1st step. If colonoscopy is unremarkable, the bleed has ceased and not recurred, and the patient does not have iron deficiency anemia (IDA), then expectant management is pursued.
Image by Lecturio.
Diagnostic algorithm for UGIB in a hemodynamically stable patient: Notice that capsule endoscopy to evaluate the small bowel should be considered if EGD and colonoscopy do not reveal a source.
Image by Lecturio.
Upper GI endoscopic findings showing a giant ulcer in the greater curvature of the antrum, which occupied halfway around the lumen
A: intermediate view
B: near view

Endoscopic picture obtained from an 83-year-old woman showing the site of angiodysplasia between the 1st and the 2nd portion of the duodenum
Image: “Angiodysplasia” by Department of Cardiology, San Raffaele Hospital, Via Olgettina 60, 20131 Milan, Italy. License: CC BY 3.0
Colonoscopy images revealing patchy and diffuse colitis throughout the colon
Image: “ Colonoscopy” by US National Library of Medicine. License: CC BY 2.0Assess the patient’s hemodynamics Hemodynamics The movement and the forces involved in the movement of the blood through the cardiovascular system. Vascular Resistance, Flow, and Mean Arterial Pressure and stabilize: