💉 PR bleeding within 24 h of admission + Hb drop ≥2 g/dL and/or transfusion ≥2 units = 🚨 emergency → requires urgent diagnosis & intervention. ⚠️ Always consider an upper GI source if unstable with haematochezia.

🩺 Initial Management (Resus First!)

🏥 Admission: In the UK, admit under Lower GI Surgery (with gastro input). Bleeds can deteriorate fast → senior surgical oversight is key.
🫁 Airway & Breathing: High-flow O₂ if hypoxic. Intubate if airway protection needed (rare in LGI bleed but consider in shock/encephalopathy).
💉 Circulation: 2 wide-bore cannulae. Send bloods: FBC, U&E, clotting, LFT, CRP, group & save/crossmatch. Begin IV crystalloids. 🚨 Activate major haemorrhage protocol if ongoing shock.
🩸 Transfusion: PRBCs guided by Hb (aim >70 g/L, >80–90 if elderly/cardiac). Balanced transfusion if massive bleed. Reverse anticoagulants (vit K, PCC, idarucizumab, andexanet as appropriate).
📊 Monitoring: Continuous vitals, urine output, stool chart, Hb 4–6 hourly. Involve ITU if unstable.

🔧 Investigations & Interventions

📷 Colonoscopy (within 24 h if stable) → diagnostic + therapeutic (clips, diathermy, adrenaline).
🧲 CT Angiography → first-line in unstable bleeds (localises active site, guides IR embolisation).
💉 Interventional Radiology → embolisation highly effective if source localised.
🔪 Surgery → subtotal colectomy in exsanguination or refractory bleeds, but high risk in frail patients.

📖 About Lower GI Bleeding

Bleeding distal to the ligament of Treitz.
Commonest in elderly and anticoagulated patients.
Mortality ~2–4% (lower than UGIB but significant in frail elderly).
⚠️ If source unclear → OGD or capsule endoscopy may be needed.

⚠️ Risk Factors for Severe Bleeding

💊 NSAIDs / anticoagulants
≥2 comorbidities
Pulse >100 bpm
SBP <115 mmHg
Age >70 years
Intestinal ischaemia

🧾 Causes (Mnemonic = DRAIN IT)

🩸 Diverticular disease – painless, brisk bleeds.
🍑 Rectal causes – haemorrhoids, fissures, anal cancer.
🧪 Adenocarcinoma (colorectal cancer).
🔥 Inflammatory – UC, Crohn’s, ischaemic colitis.
🌱 Neovascular (angiodysplasia, AVMs).
💉 Iatrogenic – post-polypectomy, anticoagulation.
🤕 Trauma (rare, e.g. foreign body).

🔎 Clinical Features

💉 Bright red PR bleed ± clots → distal source (diverticula, haemorrhoids).
🩸 Bloody diarrhoea → IBD, ischaemic colitis.
🤕 Pain + bleed → fissure, ischaemia.
⚠️ Cachexia/anaemia → malignancy.
🚨 Shock → severe ongoing bleed.
🔍 Rectal exam essential: haemorrhoids, fissure, mass, blood.
🔎 Hx AAA → think aortoenteric fistula.

📋 Common Causes Table


Cause	Typical Features	Diagnosis	Management
Haemorrhoids	Painless bright red blood ± pruritus	Proctoscopy	Conservative, banding, surgery
Fissure-in-ano	Painful defecation + bright blood	Exam ± anoscopy	Sitz baths, stool softeners, GTN ointment, sphincterotomy
Colorectal carcinoma	Bleeding + altered bowel habit, wt loss, anaemia	Colonoscopy + biopsy	Surgical resection ± chemo/radiotherapy
Diverticular disease	Painless, severe bleeds ± clots	CT colonography / colonoscopy	Conservative, endoscopic therapy, surgery if severe/recurrent
Inflammatory colitis	Bloody diarrhoea + pain ± systemic upset	Sigmoidoscopy + biopsy	Steroids, 5-ASA, biologics

🧪 Investigations

🩸 Bloods: FBC, U&E, LFTs, clotting, group & save / crossmatch.
📷 Colonoscopy (gold standard if stable).
Sigmoidoscopy for distal lesions.
Proctoscopy for anorectal pathology.
CT Angio → unstable or uncontrolled bleed.

⚕️ Management Summary

🚑 Resuscitate first → IV fluids, blood, correct clotting.
📞 Early surgical + IR involvement in severe bleeds.
📷 Colonoscopy within 24 h (if stable).
🧲 CT Angio → unstable or recurrent severe bleeds.
💉 IR embolisation if localised source found.
🔪 Surgery → refractory/uncontrolled bleeds or ≥4–5 units transfused in 24 h.
📌 Post-stabilisation: address underlying cause (IBD, malignancy, diverticulosis).

💡 Teaching Pearls:
– Painless massive bleed = diverticulosis / angiodysplasia.
– Painful bleed = fissure, IBD, ischaemia.
– Haematochezia + shock = may still be an upper GI bleed (do OGD).
– Always correct coagulopathy (warfarin/DOAC reversal).
– Frail elderly at greatest risk of decompensation.

📚 References

Cases — Lower Gastrointestinal Bleeding

Case 1 (Diverticular bleed): 👨‍🦳 A 72-year-old man presents with sudden onset painless passage of large volumes of fresh blood per rectum. He has a history of known sigmoid diverticulosis. Vitals: BP 100/60, HR 105. Hb falls from 130 → 92 g/L. Management: IV fluids, crossmatch blood, and transfusion. Urgent CT angiography localises active bleeding in the sigmoid colon. Interventional radiology performs mesenteric artery embolization. Outcome: Bleeding controlled, Hb stabilises. Discharged after 4 days, with elective outpatient colonoscopy for further assessment.
Case 2 (Haemorrhoids): 👩 A 45-year-old woman presents with bright red blood coating stool and dripping into the pan, associated with anal discomfort. No weight loss or change in bowel habit. PR exam shows engorged internal haemorrhoids. Hb normal. Management: Conservative initially: stool softeners, high-fibre diet, topical haemorrhoid cream. Rubber band ligation performed later due to persistent symptoms. Outcome: Resolution of bleeding and discomfort. Lifestyle advice (hydration, diet) reinforced to prevent recurrence.
Case 3 (Colorectal cancer): 🎗️ A 61-year-old man with iron-deficiency anaemia reports intermittent rectal bleeding and altered bowel habit. No family history. Colonoscopy shows an obstructing mass in the descending colon; biopsy confirms adenocarcinoma. Management: Stabilised with IV fluids and transfusion. Elective left hemicolectomy performed. Oncology referral for adjuvant chemotherapy. Outcome: Uneventful recovery. Enrolled in structured surveillance. Hb normalised post-surgery.

🧑‍⚕️ Teaching Commentary

Lower GI bleeding has many causes, from benign (haemorrhoids, fissures) to serious (diverticulosis, IBD, cancer). • Case 1 highlights diverticular haemorrhage: abrupt, painless, large-volume bleed often needing IR embolisation. • Case 2 shows typical haemorrhoidal bleeding: bright red, small volume, associated with straining. • Case 3 stresses the importance of excluding colorectal cancer in older patients with bleeding and anaemia. 🔑 Initial management is always ABC: resuscitation, IV access, fluids, blood crossmatch, and monitoring. Definitive management depends on the underlying pathology.

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Lower Gastrointestinal Bleeding