Understanding Obscure GI Bleeding

Obscure GI bleeding (OGIB) has been defined as overt or occult bleeding of unknown origin that persists or recurs after an initial negative bidirectional endoscopic evaluation including ileocolonoscopy and EGD. Overt OGIB refers to visible bleeding (i.e. melena or hematochezia), whereas occult OGIB refers to cases of fecal occult blood positivity and/or unexplained iron deficiency anemia. Recent advances in small-bowel imaging, including video capsule endoscopy (VCE), angiography, and device assisted enteroscopy (DAE), have made it possible to identify a small-bowel bleeding source and therefore manage the majority of patients who present with OGIB. As a result, a recent clinical guideline recommends a shift from the term obscure GI bleeding to small-bowel bleeding. The term OGIB would be reserved for patients in whom the sources of bleeding cannot be identified anywhere in the GI tract after completion of comprehensive evaluation of the entire GI tract, including the small bowel (ASGE, 2017). Approximately 300,000 hospitalizations that occur each year are due to OGIB and many of those may be attributed to readmissions as well.

Types of OGIB

There are two classifications for obscure GI bleeding: overt and occult. Overt bleeding is the term used when blood is visible. Types of overt bleeding include melena (black, tarry stools), hematemesis (vomiting of blood) and hematochezia (passage of fresh blood n or with stool). Overt bleeding patients are generally those admitted to the hospital for evaluation of active bleeding. If a patient presents with an upper GI bleed with hematemesis, an urgent EGD should be performed. If the patient presents with lower GI bleeding, symptoms of hematochezia or melena, a colonoscopy should be performed.

The term “occult small bowel bleeding” can be reserved for patients presenting with iron deficiency anemia (IDA), with or without guaiac-positive stools, who are found to have a small bowel source of bleeding. Of all the sources of GI bleeding, only a small percentage (5%) is attributed to small-bowel sources. In occult bleeding, blood is NOT visible. Occult gastrointestinal bleeding usually is discovered when fecal occult blood test results are positive, or iron deficiency anemia is detected. The initial work-up for occult bleeding typically involves colonoscopy or esophagogastroduodenoscopy, or both. In patients without symptoms indicating an upper gastrointestinal tract source, or in patients older than 50 years, colonoscopy usually is performed first.

Iron Deficiency Anemia

Iron Deficiency Anemia (IDA) is often associated with OGIB. If a patient presents with IDA, it is important to identify what is causing the anemia. Other factors that may lead to IDA include serum iron blood loss. IDA can occur with Crohn’s disease, small bowel tumors, ulcerative disease, cancers and long-­‐term use of aspirin, ibuprofen or arthritis medicines.

Although symptoms of IDA can be mild, patients may experience a change in mood, a sense of weakness or fatigue, headaches or problems concentrating. For patients who present with IDA, physicians generally will manage the deficiency with an iron therapy medication. The physician will continue to monitor the patient to observe how they are responding. If a patient is not responding to therapy, finding the cause of the anemia can help provide better long-term patient outcomes.

Patients with blood loss and iron deficiency anemia who have a negative workup on standard examinations require comprehensive evaluation. Once findings on upper and lower endoscopy prove negative, the small bowel may be assumed to be the source of blood loss. 

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