Obscure bleeding in the gastrointestinal tract

Abstract

Obscure bleeding is bleeding of unknown origin that persists or recurs after initial colonoscopy and endoscopy of the upper gastrointestinal tract. Obscure bleeding can have two forms: obscure occult bleeding (as maifest by recurrent iron-deficiency anaemia, faecal occult blood tests) and obscure overt bleeding (with recurrent passage of overt blood). Both forms can present diagnostic and management difficulties. This contribution outlines the causes and management of obscure gastrointestinal bleeding. It highlights the problems and accuracy of the various diagnostic techniques to localize obscure bleeding, with particular reference to bleeding of small-bowel origin and angiodysplasia. Patients with obscure gastrointestinal bleeding often require aggressive investigation to identify the source of bleeding. Any common cause of gastrointestinal bleeding can fall into the ‘obscure’ category if it is missed initially. Repeating initial investigations is sensible and has a definite diagnostic yield. Localization provides the opportunity for endoscopic treatment, thereby avoiding the morbidity and mortality associated with surgery in patients who often have significant comorbidity. Localization of the bleeding pre- or perioperatively also greatly reduces the risk of rebleeding if surgery is required. Medical therapy is a limited option.