Acute lower gastrointestinal bleeding
Acute lower gastrointestinal bleeding is hematochezia from a source distal to the ligament of Treitz, most often diverticular, that requires simultaneous resuscitation and localization because a brisk upper source can masquerade as the same presentation. Colonoscopy after rapid bowel preparation is the first-line diagnostic and therapeutic study in stable patients, while CT angiography localizes active bleeding in unstable or rapidly bleeding patients before catheter embolization or surgery.
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What this article covers
- Overview
Definition: acute lower gastrointestinal bleeding (LGIB) is bleeding arising in the colon or anorectum, distal to the ligament of Treitz, that presents as hematochezia (passage of maroon or red blood per rectum).
- Epidemiology
Diverticular bleeding is the leading cause of severe LGIB: it is arterial, arising from a vessel at the dome or neck of a diverticulum, and stops spontaneously in about 75% of cases.
- Risk factors
Diverticulosis: the anatomic substrate for diverticular bleeding, from segmental weakness of the artery coursing over the dome of the diverticulum.
- Pathophysiology
Diverticular bleeding: a penetrating vessel (vasa recta) at the dome of a diverticulum is eroded by chronic mechanical stress, producing painless arterial bleeding that can be brisk.
- Clinical features
Hematochezia: sudden passage of maroon or bright red blood per rectum, the hallmark presentation of LGIB.
- Differential diagnosis
Brisk upper gastrointestinal bleeding: peptic ulcer or variceal hemorrhage can transit rapidly and present as hematochezia; melena, cirrhosis stigmata, and hemodynamic instability point upstream and…
- Diagnosis
The diagnosis is established by demonstrating a bleeding source distal to the ligament of Treitz that accounts for the hematochezia, after excluding a brisk upper source; there is no scoring criteria…
- Management
Resuscitate first, in parallel with any diagnostic step: establish two large-bore peripheral IV lines (minimum 18-gauge), begin crystalloid resuscitation, and check a baseline hemoglobin.
- Complications
Hemorrhagic shock: from ongoing massive bleeding, most feared with diverticular or angiodysplasia bleeding.
- Prognosis
Most LGIB is self-limited: roughly three-quarters of diverticular bleeding episodes stop spontaneously, and overall LGIB has good outcomes and a lower mortality rate than UGIB.
- Prevention
Avoid nonaspirin NSAIDs indefinitely after a diverticular or angiodysplasia bleeding episode to reduce the risk of recurrence.
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Related articles
- Diverticular bleeding
Diverticular bleeding is painless arterial hematochezia from rupture of a vasa recta at the neck or dome of a colonic diverticulum, the most common cause of severe acute lower gastrointestinal bleeding, and it stops spontaneously in about 75% of episodes. Diagnosis rests on hemodynamic triage followed by urgent colonoscopy or CT angiography to localize the source, and management combines resuscitation with a restrictive transfusion threshold, endoscopic hemostasis, and angiographic embolization or surgery for refractory bleeding.
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