A new view of occult and obscure gastrointestinal bleeding.

Occult gastrointestinal bleeding usually is discovered when fecal occult blood test results are positive or iron deficiency anemia is detected. Fecal occult blood testing methods vary, but all have limited sensitivity and specificity. 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. About one half of patients with gastrointestinal bleeding do not have an obvious source of the bleeding. In those patients, small bowel imaging or repeat panendoscopy may be performed. Barium studies of the small bowel are widely available but have limited diagnostic utility. Mucosal lesions such as vascular ectasias, a common cause of obscure bleeding, may be missed by small bowel studies. Small bowel endoscopy is difficult to perform but has a higher diagnostic yield. Capsule endoscopy is a newer technique that allows noninvasive small bowel imaging. Radionuclide red blood cell scans or angiography may be useful in patients with active bleeding. Treatment of bleeding most often involves endoscopic ablation of the bleeding site with thermal energy, if the site is accessible. Angiographic embolization may be used to treat lesions that cannot be reached endoscopically. Diffuse vascular lesions, which are not uncommon, are difficult to treat. Medical treatment, usually with combined hormone therapy, has limited utility. Surgical treatment of obscure bleeding often fails or is not feasible because of multiple bleeding sites.