1. Finding Sources of Obscure Lower GI Bleeding William Kwan

4. Causes of Hematochezia  COLONIC BLEEDING (95%)SMALL BOWEL BLEEDING (5%)  Diverticular disease30-40Angiodysplasias  Ischemia5-10 Erosions or ulcers (K, NSAIDs)  Anorectal disease5-15Crohn's disease  Neoplasia5-10Radiation  Infectious colitis3-8Meckel's diverticulum  Postpolypectomy3-7Neoplasia  IBD3-4Aortoenteric fistula  Angiodysplasia3  Radiation colitis/proctitis1-3  Other1-5  Unknown10-25

5. 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

6. 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

7. 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

8. Going Hunting

9.  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

10. 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

11. 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

12. Strategy with Lower GI bleeding  If stable and minor bleeding  Colonoscopy  If negative, capsule endoscopy, enteroclysis, enteroscopy  If all studies negative  Colonoscopy if rebleeding

14. 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

16. 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.