Diagnosis and management of lower gastrointestinal bleeding.

Lower gastrointestinal bleeding (LGIB) can present as an acute and life-threatening event or as chronic bleeding, which might manifest as iron-deficiency anemia, fecal occult blood or intermittent scant hematochezia. Bleeding from the small bowel has been shown to be a distinct entity, and LGIB is defined as bleeding from a colonic source. Acute bleeding from the colon is usually less dramatic than upper gastrointestinal hemorrhage and is self-limiting in most cases. Several factors might contribute to increased mortality, a severe course of bleeding and recurrent bleeding, including advanced age, comorbidity, intestinal ischemia, bleeding as a result of a separate process, and hemodynamic instability. Diverticula, angiodysplasias, neoplasms, colitis, ischemia, anorectal disorders and postpolypectomy bleeding are the most common causes of LGIB. Volume resuscitation should take place concurrently upon initial patient assessment. Colonoscopy is the diagnostic and therapeutic procedure of choice, for acute and chronic bleeding. Angiography is used if colonoscopy fails or cannot be performed. The use of radioisotope scans is reserved for cases of unexplained intermittent bleeding, when other methods have failed to detect the source. Embolization or modern endoscopy techniques, such as injection therapy, thermocoagulation and mechanical devices, effectively promote hemostasis. Surgery is the final approach for severe bleeding.