Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Evaluation of occult gastrointestinal bleeding

Anne C Travis, MD, MSc, FACG, AGAF
John R Saltzman, MD, FACP, FACG, FASGE, AGAF
Section Editor
J Thomas Lamont, MD
Deputy Editor
Shilpa Grover, MD, MPH


Occult bleeding refers to the initial presentation of a positive fecal occult blood test result and/or iron deficiency anemia when there is no evidence of visible blood loss to the patient or physician [1]. By contrast, the term overt is used to describe blood loss that is visible to the patient or clinician. Overt bleeding may manifest as hematemesis, melena, or hematochezia.

The major cause of iron deficiency in developed countries is blood loss [2]. In men, the blood loss is most commonly from the gastrointestinal (GI) tract; in women, menstrual blood loss must also be considered [3]. (See "Causes and diagnosis of iron deficiency and iron deficiency anemia in adults".)

The initial evaluation of patients with occult GI bleeding will be reviewed here. The evaluation of patients with overt GI bleeding, the evaluation for occult GI blood loss as it relates to screening for colorectal cancer, and the evaluation of patients with suspected small bowel bleeding (previously referred to as obscure GI bleeding) are discussed separately. (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)" and "Approach to acute lower gastrointestinal bleeding in adults" and "Approach to acute upper gastrointestinal bleeding in adults" and "Tests for screening for colorectal cancer: Stool tests, radiologic imaging and endoscopy".)


The differential diagnosis for occult gastrointestinal (GI) bleeding is broad (table 1 and table 2). Some of the more common causes include colon cancer, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, celiac disease, small bowel tumors, and gastric antral vascular ectasias. However, less common causes, such as gastroesophageal cancers, hemosuccus pancreaticus, hemobilia, aortoenteric fistulas, endometriosis, and infections also need to be considered. In addition, hemorrhoids can rarely lead to a positive fecal occult blood test [4]. While overt bleeding from hemorrhoids can result in anemia, anemia in the setting of occult GI bleeding should not be attributed to hemorrhoids. Non-gastrointestinal sources of blood loss, such as hemoptysis and epistaxis, can also cause a positive fecal occult blood test.

The medical history and physical examination can help focus the differential diagnosis. As examples, colon cancer is a likely cause in patients older than 50 years, small bowel tumors are often seen in patients under the age of 40 years, and angiodysplasias are seen in association with several disorders, including aortic stenosis and renal disease. The presence of oral telangiectasias may signal the presence of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome), and mucocutaneous pigmentation may be due to Peutz-Jeghers syndrome in which hamartomatous polyps may ulcerate and cause occult GI bleeding. (See "Causes of upper gastrointestinal bleeding in adults" and "Etiology of lower gastrointestinal bleeding in adults".)


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Sep 2016. | This topic last updated: Nov 10, 2015.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  1. Raju GS, Gerson L, Das A, et al. American Gastroenterological Association (AGA) Institute medical position statement on obscure gastrointestinal bleeding. Gastroenterology 2007; 133:1694.
  2. Cook JD, Skikne BS. Iron deficiency: definition and diagnosis. J Intern Med 1989; 226:349.
  3. Rockey DC. Occult gastrointestinal bleeding. N Engl J Med 1999; 341:38.
  4. van Turenhout ST, Oort FA, Terhaar sive Droste JS, et al. Hemorrhoids detected at colonoscopy: an infrequent cause of false-positive fecal immunochemical test results. Gastrointest Endosc 2012; 76:136.
  5. Bini EJ, Rajapaksa RC, Valdes MT, Weinshel EH. Is upper gastrointestinal endoscopy indicated in asymptomatic patients with a positive fecal occult blood test and negative colonoscopy? Am J Med 1999; 106:613.
  6. Brint SL, DiPalma JA, Herrera JL. Is a Hemoccult-positive rectal examination clinically significant? South Med J 1993; 86:601.
  7. Eisner MS, Lewis JH. Diagnostic yield of a positive fecal occult blood test found on digital rectal examination. Does the finger count? Arch Intern Med 1991; 151:2180.
  8. Burke CA, Tadikonda L, Machicao V. Fecal occult blood testing for colorectal cancer screening: use the finger. Am J Gastroenterol 2001; 96:3175.
  9. Rockey DC, Koch J, Cello JP, et al. Relative frequency of upper gastrointestinal and colonic lesions in patients with positive fecal occult-blood tests. N Engl J Med 1998; 339:153.
  10. Allison JE, Sakoda LC, Levin TR, et al. Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics. J Natl Cancer Inst 2007; 99:1462.
  11. Allison JE, Tekawa IS, Ransom LJ, Adrain AL. A comparison of fecal occult-blood tests for colorectal-cancer screening. N Engl J Med 1996; 334:155.
  12. Whitlock EP, Lin JS, Liles E, et al. Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force. Ann Intern Med 2008; 149:638.
  13. Stroehlein JR, Fairbanks VF, McGill DB, Go VL. Hemoccult detection of fecal occult blood quantitated by radioassay. Am J Dig Dis 1976; 21:841.
  14. Pignone M. Faecal occult-blood screening in Burgundy. Lancet 2004; 364:741.
  15. Levin B, Hess K, Johnson C. Screening for colorectal cancer. A comparison of 3 fecal occult blood tests. Arch Intern Med 1997; 157:970.
  16. Van Dam J, Bond JH, Sivak MV Jr. Fecal occult blood screening for colorectal cancer. Arch Intern Med 1995; 155:2389.
  17. Hewitson P, Glasziou P, Watson E, et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol 2008; 103:1541.
  18. Saito H. Screening for colorectal cancer by immunochemical fecal occult blood testing. Jpn J Cancer Res 1996; 87:1011.
  19. Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. CA Cancer J Clin 2008; 58:130.
  20. Morikawa T, Kato J, Yamaji Y, et al. A comparison of the immunochemical fecal occult blood test and total colonoscopy in the asymptomatic population. Gastroenterology 2005; 129:422.
  21. Guittet L, Bouvier V, Mariotte N, et al. Comparison of a guaiac based and an immunochemical faecal occult blood test in screening for colorectal cancer in a general average risk population. Gut 2007; 56:210.
  22. van Rossum LG, van Rijn AF, Laheij RJ, et al. Random comparison of guaiac and immunochemical fecal occult blood tests for colorectal cancer in a screening population. Gastroenterology 2008; 135:82.
  23. Bull-Henry K, Al-Kawas FH. Evaluation of occult gastrointestinal bleeding. Am Fam Physician 2013; 87:430.
  24. Chen YK, Gladden DR, Kestenbaum DJ, Collen MJ. Is there a role for upper gastrointestinal endoscopy in the evaluation of patients with occult blood-positive stool and negative colonoscopy? Am J Gastroenterol 1993; 88:2026.
  25. Geller AJ, Kolts BE, Achem SR, Wears R. The high frequency of upper gastrointestinal pathology in patients with fecal occult blood and colon polyps. Am J Gastroenterol 1993; 88:1184.
  26. Hsia PC, al-Kawas FH. Yield of upper endoscopy in the evaluation of asymptomatic patients with Hemoccult-positive stool after a negative colonoscopy. Am J Gastroenterol 1992; 87:1571.
  27. Rockey DC, Cello JP. Evaluation of the gastrointestinal tract in patients with iron-deficiency anemia. N Engl J Med 1993; 329:1691.
  28. Till SH, Grundman MJ. Prevalence of concomitant disease in patients with iron deficiency anaemia. BMJ 1997; 314:206.
  29. Kepczyk T, Kadakia SC. Prospective evaluation of gastrointestinal tract in patients with iron-deficiency anemia. Dig Dis Sci 1995; 40:1283.
  30. Gerson LB, Fidler JL, Cave DR, Leighton JA. ACG Clinical Guideline: Diagnosis and Management of Small Bowel Bleeding. Am J Gastroenterol 2015; 110:1265.
  31. Rockey DC. Occult and obscure gastrointestinal bleeding: causes and clinical management. Nat Rev Gastroenterol Hepatol 2010; 7:265.
  32. Sawhney MS, McDougall H, Nelson DB, Bond JH. Fecal occult blood test in patients on low-dose aspirin, warfarin, clopidogrel, or non-steroidal anti-inflammatory drugs. Dig Dis Sci 2010; 55:1637.
  33. Greenberg PD, Cello JP, Rockey DC. Asymptomatic chronic gastrointestinal blood loss in patients taking aspirin or warfarin for cardiovascular disease. Am J Med 1996; 100:598.
  34. Brenner H, Tao S, Haug U. Low-dose aspirin use and performance of immunochemical fecal occult blood tests. JAMA 2010; 304:2513.
  35. Kershenbaum A, Lavi I, Rennert G, Almog R. Fecal occult blood test performance indicators in warfarin-treated patients. Dis Colon Rectum 2010; 53:224.
  36. Zwas FR, Lyon DT. Occult GI bleeding in the alcoholic. Am J Gastroenterol 1996; 91:551.
  37. Bini EJ, Micale PL, Weinshel EH. Evaluation of the gastrointestinal tract in premenopausal women with iron deficiency anemia. Am J Med 1998; 105:281.
  38. Vannella L, Aloe Spiriti MA, Cozza G, et al. Benefit of concomitant gastrointestinal and gynaecological evaluation in premenopausal women with iron deficiency anaemia. Aliment Pharmacol Ther 2008; 28:422.