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For further information, see CMDT Part 15-07: Gastrointestinal Bleeding

Key Features

Essentials of Diagnosis

  • Hematochezia usually present

  • 10% of cases of hematochezia are due to upper gastrointestinal source

  • Stable patients can be evaluated by colonoscopy

  • Massive active bleeding calls for evaluation with sigmoidoscopy, upper endoscopy, angiography, or nuclear bleeding scan

General Considerations

  • Lower GI bleeding is defined as that arising below the ligament of Treitz, ie, small intestine or colon; up to 95% of cases derive from the colon

  • Lower tract bleeding

    • 33% less common than upper tract bleeding

    • Tends to have a more benign course

    • Is less likely to present with shock or orthostasis (< 5%) or to require transfusions (< 40%)

  • Spontaneous cessation in > 75%; hospital mortality is about 1%

  • Most common causes are

    • Diverticulosis

    • Angioectasias

    • Neoplasms

    • Inflammatory bowel disease

    • Anorectal disease

    • Ischemic colitis

    • Radiation-induced proctitis

    • Acute infectious colitis

  • Rare causes include

    • Vasculitic ischemia

    • Solitary rectal ulcer

    • NSAID-induced ulcers in the small bowel or right colon

    • Small bowel diverticula

    • Colonic varices

  • Risk of lower GI bleeding is increased in patients taking

    • Aspirin

    • Nonaspirin antiplatelet agents

    • Nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Diverticular bleeding

    • Acute, painless, large-volume maroon or bright red hematochezia occurs in 3–5% of patients with diverticulosis, often associated with the use of NSAIDs

    • Bleeding more commonly originates on the right side

    • > 95% require < 4 units of blood transfusion

    • Bleeding subsides spontaneously in 80% of patients but may recur in up to 25%

  • Angioectasias

    • Painless bleeding ranging from occult blood loss to melena or hematochezia

    • Bleeding most commonly originates in the cecum and ascending colon

    • Causes: congenital; hereditary hemorrhagic telangiectasia; autoimmune disorders, especially systemic sclerosis (scleroderma)

  • Neoplasms: benign polyps and carcinoma cause chronic occult blood loss or intermittent anorectal hematochezia

  • Anorectal disease

    • Small amounts of bright red blood noted on the toilet paper, streaking of the stool, or dripping into the toilet bowl

    • Clinically significant blood loss can sometimes occur

  • Ischemic colitis

    • Hematochezia or bloody diarrhea associated with mild cramps

    • In most cases, bleeding is mild and self-limited


  • Diverticular bleeding is more common in patients age > 50 years

  • Angiodysplasia bleeding is more common in patients age > 70 years and in those with chronic kidney disease

  • Ischemic colitis is most commonly seen

    • In older patients due to atherosclerotic disease—postoperatively, after ileoaortic or abdominal aortic aneurysm surgery

    • In younger patients due to vasculitis, coagulation disorders, estrogen therapy, and long-distance running

Clinical Findings

Symptoms and Signs

  • Brown stools mixed or streaked with blood suggest rectosigmoid or anal source

  • Painless large-volume bleeding suggests diverticular bleeding

  • Maroon stools suggest a right colon or small intestine source

  • Black stools (melena) suggest a source proximal to the ligament of Treitz, but dark maroon stools arising from small intestine or right colon may be misinterpreted as "melena"

  • Bright red blood ...

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