GI Bleeding - Melena & Hematochezia

Lower GI tract bleeding occurs distal to the ligament of Treitz (which separates the duodenum from the jejunum) and refers to the passage of either bright red blood per rectum (hematochezia), maroon stools, or black, tarry stools (melena). Hematochezia suggests either bleeding from the lower intestinal tract or very brisk bleeding from higher in the intestinal tract. Melena suggests that the blood has had time to be processed by the intestinal tract, implying slower bleeding that originates higher in the intestinal tract.

Differential Diagnosis

• Anatomic lesions
  –Diverticular bleeding causes 30–50% of all cases of massive rectal bleeding; associated with mild, crampy pain, but can be painless; not associated with diverticulitis
  –Meckel's diverticulum
• Vascular lesions
  –Angiodysplasia (arteriovenous malformation): Most frequent cause in older patients; bleeding tends to be episodic and self-limited; painless; increased risk with increased age
• Neoplastic lesions
  –Colon cancer or polyps: Causes 10% of cases of lower GI bleeding in patients >50 years; generally low-grade, recurrent bleeding
  –Rectal cancer
  –Small bowel tumors
• Inflammatory lesions
  –Colitis/ulcers (e.g., inflammatory bowel disease, infectious colitis, ischemic colitis, radiation colitis)
  –Ischemic colitis generally presents with abdominal pain
  –Ulcerative colitis more associated with gross rectal bleeding
  –Crohn's disease more commonly associated with diffuse crampy abdominal pain, whereas ulcerative colitis is more localized to left lower quadrant
• Anorectal lesions
  –Hemorrhoids are the most common cause of rectal bleeding in patients younger than 50 years old; usually painless bleeding
  –Fissures
  –Polyps
  –Idiopathic rectal ulcers

• Aortoenteric fistula: Must be suspected in any patient with a known aortic graft (e.g., prior aortic aneurysm repair or occlusive aortic disease)
• Idiopathic in up to 15% of cases
• Upper GI bleeding
• Systemic bleeding disorders (e.g., hemophilia, excessive anticoagulation, thrombocytopenia)

Workup and Diagnosis

• Evaluate the severity of bleeding (e.g., signs of shock, orthostatic hypotension, decreased hematocrit)—if impending shock or exsanguination, emergent resuscitation (see below) and surgical intervention are indicated
• Determine the source of bleeding
  –Rectal examination
  –Rule out upper GI bleeding by nasogastric tube aspiration or upper GI endoscopy
  –Abdominal X-ray to rule out perforation or obstruction (before initiating colonoscopy)
  –Colonoscopy is usually diagnostic for the bleeding source
  –Angiography is used for active, heavy bleeding and/or if colonoscopy is inconclusive
  –Tagged RBC scan is helpful for Meckel's diverticula
  • Initial labs should include CBC, coagulation workup (PT/PTT/INR, bleeding time, platelet count), glucose, electrolytes, BUN/creatinine, LFTs, albumin, toxicology screen (e.g., for alcohol), and stool ova/parasites culture
  • ECG may be indicated to rule out cardiac ischemia secondary to severe anemia, especially in patients with known diabetes and/or CAD

  Treatment

  • Ensure adequate airway, breathing, and circulation
  • Stabilize and resuscitate patients as necessary
    –Insert two large-bore IV lines
    –Administer IV fluids
    –Type and cross match two units of packed RBCs
    –Administer blood transfusion if necessary
    –Correct coagulopathies if present (e.g., fresh frozen plasma, vitamin K, platelets)
  • Several options are available to treat persistent bleeding: Endoscopic sclerotherapy, electrocautery, or laser coagulation; angiographic embolization; or resection
  • Diverticular hemorrhage: Resection may be indicated
  • Angiodysplasia: Endoscopy or resection
  • Colorectal cancer and/or polyps: Excision or resection
  • Infectious colitis: Appropriate antibiotic regimens
  • Inflammatory bowel disease: Steroids and aminosalicylates; resection for severe disease
  • Aortoenteric fistula requires repair of bowel, graft excision, and extra-anatomic bypass graft

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

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Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Bloody diarrhea: Introduction (review 73 causes)
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More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

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