A 62-year-old man with no significant past medical history presents with acute lower abdominal pain and bloody stools. On examination, he is haemodynamically stable (BP 130/80 mmHg, HR 88/min), and digital rectal examination shows bright red blood. Abdominal examination reveals mild left lower quadrant tenderness. Laboratory tests show Hb 11.2 g/dL (baseline unknown) and normal coagulation. What is the most appropriate next step in management?

Explanation

## Clinical Presentation This patient has acute lower GI bleeding with: - Haemodynamic stability - Bright red blood per rectum (suggests distal source) - Mild left lower quadrant tenderness (suggests left colon/sigmoid source) - No signs of mesenteric ischaemia (stable vitals, mild localised tenderness, no severe pain) ## Rationale for Correct Answer **Key Point:** In a haemodynamically stable patient with acute lower GI bleeding, **colonoscopy is the first-line diagnostic and therapeutic modality**. It allows visualisation, localisation, and treatment of bleeding lesions (diverticulosis, angiodysplasia, polyps, IBD). **High-Yield:** Colonoscopy has 90% sensitivity for lower GI bleeding sources and allows therapeutic intervention (argon plasma coagulation, injection therapy, polypectomy, clipping). It should be performed after bowel preparation (even in active bleeding, polyethylene glycol is safe and improves visualisation). **Clinical Pearl:** The left lower quadrant tenderness and bright red blood suggest a sigmoid or left colon source — exactly what colonoscopy can reach and treat. ## Why Other Options Are Incorrect | Modality | Indication | Why Not Here | |----------|-----------|---------------| | **CT angiography** | Suspected mesenteric ischaemia or massive bleeding | Patient is stable; no signs of ischaemia (no severe pain, normal lactate expected) | | **Observation alone** | Minor bleeding, self-limited | Ongoing bleeding warrants investigation and treatment | | **Meckel's scan** | Suspected Meckel's diverticulum in young patients | Rare in this age group; colonoscopy is first-line | **Clinical Pearl:** Meckel's scan is reserved for recurrent or obscure bleeding in younger patients when colonoscopy and upper endoscopy are unrevealing.