Acute lower gastrointestinal bleeding (LGIB) is a common presentation to the emergency department (ED) and is defined as bleeding distal to the ligament of Treitz (i.e., the distal small intestine, large intestine, rectum, and anus) [[1], [2], [3], [4], [5], [6], [7]]. LGIB is common, accounting for over 270,000 ED visits in the United States and resulting in over 110,000 admissions [3,[7], [8], [9], [10], [11]]. The incidence has been rising over time with current rates approaching 87 cases per 100,000 people [2,3,[8], [9], [10], [11]].

LGIB has a variety of etiologies, including anatomic (e.g., diverticular bleeding), vascular (e.g., angiodysplasia, ischemic), inflammatory (e.g., infectious, inflammatory bowel disease), and neoplastic (Table 1) [[2], [3], [4], [5], [6], [7]]. Diverticular bleeding is the most common etiology overall, while hemorrhoids are more common in those <50 years of age and vascular causes more common in those over 65 years of age [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]]. Most cases (85%) of LGIB resolve spontaneously, but rebleeding can occur in up to 38% of patients within one year, and 25% will require blood product transfusion [[1], [2], [3], [4], [5],12,15,[17], [18], [19]]. Mortality rates can reach 3.9% for admitted patients, depending on the source of bleeding and patient comorbidities [[2], [3], [4], [5], [6],[12], [13], [14], [15], [16], [17], [18], [19], [20]]. The following questions will highlight several key updates in the diagnosis and management of LGIB, but this paper is not intended to serve as a review of the condition in its entirety.