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GI Bleeding, Lower

 

  • Defined as bleed distal to ligament of Treitz, and typically presents as hematochezia, though small bowel or R colonic source can present as melena
  • Brisk upper GI bleed can also result in hematochezia (comprises 10% of patients with hematochezia)
  • Differential diagnosis:
    • Anatomic: diverticulosis (R sided more likely to bleed), fissure, ulcer
    • Vascular: angiodysplasia, ischemia, hemorrhoids
    • Inflammatory: infection, IBD, XRT
      • Pathogens: Shigella, salmonella, capylobacter, E coli
        • Enterohemorrhagic E coli (e.g. O157:H7) produces Shiga-toxin, and can result in hemolytic-uremic syndrome
          • Should be suspected in patients with hematochezia, abdominal pain, and absence of fever
          • Antibiotic therapy can increase toxin release and potentially the risk of HUS, and should not be used routinely

Therapy

  • Resuscitation
  • Consider NGT to rule out UGIB, but remember that a negative NG lavage does not rule out an upper source
  • Diagnosis:
    • Colonoscopy: allows for therapy, but requires prep, sedation, and sensitivity may be limited
    • Tagged RBC scan: requires active bleed at a rate of 0.5 ml/min, and localization poor - used to screen for possible angiography candidates
    • Angiography: requires active bleed at rate of 1.5 cc/min, localizes well, and allows for therapeutic intervention

 

(Christopher Woo MD, 11/1/10)