Although acute LGIB is only about one fifth as common and is usually less hemodynamically significant than upper gastrointestinal bleeding, it presents numerous unique clinical challenges. The best diagnostic approach for patients with active bleeding is unknown, but urgent prepared colonoscopy is safe and likely to be beneficial (Fig. 3, Table 2). In patients who have aggressive bleeding or recurrent bleeding, it is critical for the practitioner to judge when angiography and surgery are necessary.