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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, AGAF


Occult gastrointestinal (GI) 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 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, 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".)

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Literature review current through: Nov 2017. | This topic last updated: Oct 24, 2016.
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