ICU · GI & nutrition / surgical

Acute lower gastrointestinal bleeding — diverticular, angiodysplasia, colitis and the resuscitate-to-surgery pathway

Also known as Lower GI bleed · LGIB · Hematochezia · Diverticular bleed · Massive rectal bleeding · Angiodysplasia · Ischaemic colitis · Oakland score · CT angiography · Tagged RBC scan · Angioembolisation · Subtotal colectomy · Heyde syndrome · Aortoenteric fistula

Acute lower gastrointestinal bleeding (LGIB) is bleeding arising distal to the ligament of Treitz, presenting most often with hematochezia (bright red blood per rectum) and less commonly with maroon stools or right-sided melena. The dominant causes are diverticular bleeding (the commonest cause — painless, massive, self-limiting), colonic angiodysplasia (painless and recurrent in the elderly), colitis (ischaemic, inflammatory and infectious), anorectal sources such as haemorrhoids, and colorectal malignancy or post-polypectomy. Most bleeds stop spontaneously. The management ladder is resuscitation with crystalloid and restrictive transfusion (TRICC trigger Hb <70 g/L) → exclude an upper GI source (upper endoscopy when hematochezia accompanies haemodynamic instability) → bowel preparation and colonoscopy (nonurgent for most inpatients; urgent within 24 h reserved for higher-risk patients) → CT angiography (CTA) for brisk ongoing bleeding or when colonoscopy is non-diagnostic → catheter mesenteric angiography with superselective embolisation if CTA is positive → and segmental or subtotal colectomy as the last resort for refractory haemorrhage. The Oakland score (threshold <=8, 95% probability of safe discharge in derivation) identifies low-risk patients safe for outpatient management. Cause-specific management differs: diverticular (endoscopic haemostasis, often self-limiting), angiodysplasia (ablation, consider aortic stenosis / Heyde syndrome), IBD (treat the flare, avoid over-instrumentation), ischaemic colitis (supportive — fluids, antibiotics, no endoscopic therapy unless right-sided/gangrenous).