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
- Enterohemorrhagic E coli (e.g. O157:H7) produces Shiga-toxin, and can result in hemolytic-uremic syndrome
- Pathogens: Shigella, salmonella, capylobacter, E coli
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)