Finding Sources of Obscure Lower GI

BleedingWilliam 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 disease5-15 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.