Gastrointestinal Bleeding, Acute Lower

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

Demographics

• 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 ...