Key Concepts

• LGIB comprises 30–40% of all GI bleeds and is the most common cause of hospitalization due to GI disease in the United States.
• The incidence of LGIB is increasing, especially in octogenarians.
• The most common cause of LGIB is diverticular disease followed by anorectal disease and ischemia.
• A focused H&P (history and physical examination) is most effective in determining the cause of bleeding, and initial resuscitation should be focused on restoring hemodynamic stability with volume and/or blood.
• Characteristics of timing, type of bleeding, volume, and anoscopy can help to rapidly identify appropriate treatment based on potential source and rate of bleeding.
• Appropriate risk stratification can help better predict morbidity and mortality as well as guide appropriate management schemes.
• Upper and lower endoscopy is the preferred initial mode of diagnosis for LGIB. This method best allows for not only potential source identification but offers the potential for therapeutic intervention.
• Radiologic studies can be effective early diagnostic modalities in identifying the source of bleeding. CT angiography has a high sensitivity and specificity and is widely available. Catheter-based angiography can both diagnose and potentially treat bleeding sources if bleeding is brisk enough via transcatheter embolization.
• Nuclear scintigraphy, either via ^99mTc-sulfur colloid or ^99mTc-labeled RBC, can be used to identify bleeding sources that are intermittent or too slow to be identified by CTA or direct angiography.
• Recurrent LGIB is a common problem, and repeated evaluation has additive success rates.
• All attempts at localization should be made in the stable patient prior to consideration of surgical intervention.
• Obscure GI bleeding is defined as bleeding from a source that has not been identified after appropriate endoscopic and radiologic evaluation.
• Most sources of obscure GI bleeding tend to come from the small bowel, and capsule endoscopy is indicated to try and diagnose.
• Double balloon enteroscopy is an advanced modality which may be employed to diagnose and treat bleeding sources in the proximal small bowel.
• Surgery is indicated in patients in whom conservative measures have failed and/or bleeding is causing hemodynamic instability or who have reached significant transfusion thresholds.
• For refractory LGIB that are colonic in origin, but remain unlocalized, a total colectomy with ileostomy should be performed.
• For bleeding from an ongoing or refractory source that is localized, a segmental colectomy may be performed.
• Combining clinical pathways incorporating risk stratification may be helpful in providing a more systematic approach to management of LGIB and improving patient outcomes.