Chapter 042. Gastrointestinal Bleeding (Part 5) LOWER GIB (Fig. 42-2) Patients with hematochezia and hemodynamic instability should have upper endoscopy to rule out an upper GI source before evaluation of the lower GI tract. Patients with presumed LGIB may undergo early sigmoidoscopy for the detection of obvious, low-lying lesions. However, the procedure is difficult with brisk bleeding, and it is usually not possible to identify the area of bleeding. Sigmoidoscopy is useful primarily in patients <40 years with minor bleeding. Figure 42-2 Suggested algorithm for patients with acute lower gastrointestinal bleeding. Sequential recommendations under "Hemodynamic instability" assume a test is found to be nondiagnostic before next test is performed. * Some suggest colonoscopy for any degree of rectal bleeding in patients <40 years as well. †If massive bleeding does not allow time for colonic lavage, proceed to angiography. Tc-RBC, 99m technetium-labeled red blood cell. Colonoscopy after an oral lavage solution is the procedure of choice in patients admitted with LGIB unless bleeding is too massive or unless sigmoidoscopy has disclosed an obvious actively bleeding lesion. 99m Tc-labeled red cell scan allows repeated imaging for up to 24 h and may identify the general location of bleeding. However, radionuclide scans should be interpreted with caution because results, especially from later images, are highly variable. In active LGIB, angiography can detect the site of bleeding (extravasation of contrast into the gut) and permits treatment with intraarterial infusion of vasopressin or embolization. Even after bleeding has stopped, angiography may identify lesions with abnormal vasculature, such as vascular ectasias or tumors. GIB OF OBSCURE ORIGIN Obscure GIB is defined as persistent or recurrent bleeding for which no source has been identified by routine endoscopic and contrast x-ray studies; it may be overt (e.g., melena, hematochezia) or occult. Push enteroscopy, with a specially designed enteroscope or a pediatric colonoscope to inspect the entire duodenum and part of the jejunum, is generally the next step. Push enteroscopy may identify probable bleeding sites in 20–40% of patients with obscure GIB. Video capsule endoscopy, which allows endoscopic examination of the entire small intestine, increases diagnostic yield in obscure GIB: a systematic review of 14 trials comparing push enteroscopy to capsule revealed "clinically significant findings" in 26% and 56% of patients, respectively. However, lack of control of the capsule prevents its manipulation and full visualization of the intestine; in addition, tissue cannot be sampled and therapy cannot be applied. A new endoscopic technique, double-balloon enteroscopy, allows the endoscopist to potentially examine and provide therapy to much or all of the small intestine. If enteroscopy and video capsule endoscopy are negative or unavailable, a specialized radiographic examination of the small bowel (e.g., enteroclysis) should be performed. Newer imaging techniques being investigated include CT and MR enterography. Patients with continued obscure GIB who require transfusions or repeated hospitalizations warrant further investigations. 99m Tc-labeled red blood cell scintigraphy should be employed. Angiography is useful even if bleeding has subsided, since it may disclose vascular anomalies or tumor vessels. 99m Tc- pertechnetate scintigraphy for diagnosis of Meckel's diverticulum should be done, especially in the evaluation of young patients. When all tests are unrevealing, intraoperative endoscopy is indicated in patients with severe recurrent or persistent bleeding requiring repeated transfusions. OCCULT GIB Occult GIB is manifested by a positive test for fecal occult blood or iron- deficiency anemia. Evaluation of a positive test for fecal occult blood generally should begin with colonoscopy, particularly in patients >40 years. If evaluation of the colon is negative, many perform upper endoscopy only if iron-deficiency anemia or upper GI symptoms are present, while others recommend upper endoscopy in all patients since up to 25–40% of these patients may have some abnormality noted on upper endoscopy. If standard endoscopic tests are unrevealing, enteroscopy, video capsule endoscopy, and/or enteroclysis may be considered in patients with iron-deficiency anemia. Further Readings Chan FK et al: Proton pump inhibitor plus a COX-2 inhibitor for the prevention of recurrent ulcer bleeding in patients with arthritis: A double blinded, randomized trial. Gastroenterology 130:A-105, 2006 Cipolletta L et al: Outpatient management for low-risk nonvariceal upper GI bleeding: A randomized controlled trial. Gastrointest Endosc 55:1, 2002 [PMID: 11756905] Conrad SA et al: Randomized, double-blind comparison of immediate- release omeprazole oral suspension versus intravenous cimetidine for the prevention of upper gastrointestinal bleeding in critically ill patients. Crit Care Med 33:760, 2005 [PMID: 15818102] D'Amico G et al: Pharmacological treatment of portal hypertension: An evidence-based approach. Semin Liver Dis 19:475, 1999 [PMID: 10643630] Henderson JM et al: Distal splenorenal shunt versus transjugular intrahepatic portal systematic shunt for variceal bleeding: A randomized trial. Gastroenterology 130:1643, 2006 [PMID: 16697728] Laine L, Cook D: Endoscopic ligation compared with sclerotherapy for treatment of esophageal variceal bleeding: A meta-analysis. Ann Intern Med 123:280, 1995 [PMID: 7611595] Lau JYW et al: Effect of intravenous omeprazole on recurrent bleeding after endoscopic treatment of bleeding peptic ulcers. N Engl J Med 343:310, 2000 [PMID: 10922420] Marmo R et al: Dual therapy versus monotherapy in endoscopic treatment of high-risk bleeding ulcers: A meta-analysis of controlled trials. Am J Gastroenterol 102:279, 2007 [PMID: 17311650] Rockall TA et al: Risk assessment after acute upper gastrointestinal haemorrhage. Gut 38:316, 1996 [PMID: 8675081] Triester SL et al. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with obscure gastrointestinal bleeding. Am J Gastroenterol 100:2407, 2005 [PMID: 16279893] Bibliography Cook DJ et al: A comparison of sucralfate and ranitidine for the prevention of upper gastrointestinal bleeding in patients requiring mechanical ventilation. N Engl J Med 338:791, 1998 [PMID: 9504939] . Chapter 042. Gastrointestinal Bleeding (Part 5) LOWER GIB (Fig. 42-2) Patients with hematochezia and hemodynamic. difficult with brisk bleeding, and it is usually not possible to identify the area of bleeding. Sigmoidoscopy is useful primarily in patients <40 years with minor bleeding. Figure 42-2. obscure gastrointestinal bleeding. Am J Gastroenterol 100:2407, 2005 [PMID: 16279893] Bibliography Cook DJ et al: A comparison of sucralfate and ranitidine for the prevention of upper gastrointestinal