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Finding Sources of Obscure Lower GI Bleeding William Kwan Causes of Hematochezia COLONIC BLEEDING (95%) SMALL BOWEL BLEEDING (5%) Diverticular disease 30-40 Angiodysplasias Ischemia 5-10 Erosions or ulcers (K, NSAIDs) Anorectal disease 5-15 Crohn's disease Neoplasia 5-10 Radiation Infectious colitis 3-8 Meckel's diverticulum Postpolypectomy 3-7 Neoplasia IBD 3-4 Aortoenteric fistula Angiodysplasia 3 Radiation colitis/proctitis1-3 Other 1-5 Unknown 10-25 Causes of Hematochezia Diverticulosis Bleeding occurs in only 3-5% Left-sided source more common when diagnosed by colonoscopy Right-sided source more common when diagnosed by angiography Angiodysplasia Most common in cecum and ascending colon When in the small bowel, presents as iron deficiency anemia and rarely as hematochezia Causes of Hematochezia Hemorrhoids Ischemic colitis Neoplasms NSAID-induced injury in terminal ileum and proximal colon IBD 10-15% of hematochezia caused by upper GI bleed History NSAIDs & ASA strongly associated with lower GI bleeding just as with upper GI bleeding Stercoral ulcers caused by severe constipation Recent polypectomy Hypovolemia preceding bleed suggests ischemic colitis Going Hunting Going Hunting Bleeding source not found in 25% KUB to look for perforation or obstruction NG aspirate Colonoscopy No agreement over whether prep is needed because of increased risk of perforation with unpreped colon Radionuclide imaging Can detect slow bleeds at 0.1-0.5ml/min More sensitive but less specific than angiography Going Hunting Angiography Requires bleeding of at least 1ml/min Very specific but not very sensitive May cause bowel infarction, renal failure Small bowel evaluation Push enteroscopy can allow evaluation of the first 60cm of jejunum Video capsule to evaluate the remainder Meckel scan Strategy with Lower GI bleeding If persistently unstable and major bleeding, proceed to surgery If colonic source, subtotal colectomy with ileorectal anastomosis If small bowel source, resection If no identified source, intraoperative enteroscopy followed by resection If stable and major bleeding Tagged red cell scan If positive, follow with angiography If negative, capsule endoscopy, enteroclysis, enteroscopy Strategy with Lower GI bleeding If stable and minor bleeding Colonoscopy If negative, capsule endoscopy, enteroclysis, enteroscopy If all studies negative Colonoscopy if rebleeding Don’t Forget In addition to basic labs (CBC, Chemistries, Coags), obtaining type and cross Two large bore peripheral IV’s Rectal exam as up to 40% of rectal cancers can be detected this way References Bounds, BC and PB Kelsey. Lower Gastrointestinal Bleeding. Gastrointestinal Endoscopy Clinics of North America. 2007: 17, 273-88. Townsend: Sabiston Textbook of Surgery. 18th ed.
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