Key Facts

GI bleeding is a common and potentially life-threatening emergency. Prompt recognition, resuscitation, risk stratification, and appropriate investigation are essential.

Epidemiology

Acute upper GI bleeding: incidence ~100-150 per 100,000 per year; mortality ~10%. Lower GI bleeding: incidence ~20-30 per 100,000 per year; mortality ~3-5%. GI bleeding accounts for a significant proportion of emergency medical and surgical admissions.

Aetiology

See separate entries for Upper GI Bleeding and Lower GI Bleeding for detailed causes.

Pathophysiology

GI bleeding results from mucosal erosion, vascular malformation, or structural lesion disrupting blood vessel integrity. The clinical significance depends on: rate of bleeding, volume lost, patient's cardiovascular reserve, and underlying cause. Massive GI bleeding (>150 mL/min or requiring >4 units in 24 hours) can rapidly cause haemodynamic collapse.

Upper GI Bleeding

• Haematemesis: fresh blood (arterial/severe) or coffee-ground (slower/partially digested)
• Melaena: black, tarry, offensive stools (blood altered by gastric acid — typically >50 mL blood needed)
• Note: brisk UGIB can present as haematochezia (fresh PR blood)

Lower GI Bleeding

• Haematochezia: bright red or maroon blood PR
• On wiping/in pan: often haemorrhoids/fissure
• Mixed with stool: colonic pathology

Assessment of Severity

• Haemodynamic status (pulse, BP, postural drop)
• Evidence of shock (tachycardia, hypotension, cool peripheries)
• Rate of bleeding (ongoing haematemesis, fresh melaena)
• Comorbidities and anticoagulation

Red Flags

• Haemodynamic instability (pulse >100, SBP <100)
• Fresh haematemesis (ongoing arterial bleed)
• Suspected variceal bleeding (known/suspected liver disease)
• Melaena with haemodynamic compromise
• Anticoagulated patient with GI bleeding

Bedside

• A-E assessment: pulse, BP, RR, SpO₂, GCS
• DRE: melaena, fresh blood, mass
• NG aspirate: coffee-ground/blood confirms UGIB (not routinely recommended if clear clinical picture)

Bloods

• FBC: Hb (may be normal initially in acute bleed; takes 24-72 hours to fall)
• U&Es: urea disproportionately raised in UGIB (protein absorption from blood)
• LFTs: liver disease assessment
• Coagulation (INR/PT): anticoagulant therapy, liver disease
• Group and save/crossmatch: 2-6 units depending on severity
• Lactate: tissue perfusion

Risk Scores

• Glasgow-Blatchford Score (GBS): pre-endoscopy; uses Hb, urea, SBP, pulse, melaena, syncope, liver disease, heart failure; score 0 = very low risk → may be discharged for outpatient OGD
• Rockall Score: pre- and post-endoscopy; predicts rebleeding and mortality

Imaging/Endoscopy

• OGD: within 24 hours for all UGIB (within 12 hours if variceal/haemodynamically unstable)
• Colonoscopy: for stable LGIB (after bowel preparation)
• CT angiography: for massive/ongoing bleeding (identifies active extravasation)
• Mesenteric angiography + embolisation: for ongoing bleeding localised on CT
• Capsule endoscopy: for obscure GI bleeding (negative OGD and colonoscopy)

Non-pharmacological

• Resuscitation: A-E, large-bore IV access × 2, crossmatch
• Transfusion: target Hb 70-80 g/L (restrictive strategy — overtransfusion increases rebleeding in variceal bleeding)
• Correct coagulopathy: vitamin K if warfarin, specific reversal agents for DOACs; FFP/platelets as needed

Pharmacological

• UGIB (non-variceal): IV PPI (omeprazole 80 mg bolus then 8 mg/hr infusion × 72 hours if high-risk endoscopic stigmata)
• UGIB (variceal): IV terlipressin 2 mg stat then 1-2 mg QDS + prophylactic antibiotics (ceftriaxone 1 g OD)
• Tranexamic acid: no longer routinely recommended for GI bleeding (HALT-IT trial showed no benefit and increased VTE)

Surgical/Interventional

• Endoscopic haemostasis: thermal coagulation, clips, injection (adrenaline), band ligation (varices)
• Interventional radiology: embolisation for failed endoscopic therapy or ongoing arterial bleeding
• Surgery: last resort for uncontrolled bleeding (under-running of ulcer, partial gastrectomy, colectomy)

Referral Criteria

• All acute GI bleeding: emergency assessment
• GBS 0: may be discharged for outpatient OGD within 24 hours
• Variceal bleeding: urgent gastroenterology/hepatology + consider TIPSS
• Massive LGIB: surgical and interventional radiology teams

UGIB overall mortality is ~10% (unchanged over decades despite improved endoscopic therapy — aging population, more comorbidities). Variceal bleeding mortality is 15-20% per episode. LGIB mortality is lower (~3-5%). Most GI bleeding (80-85%) stops spontaneously. Peptic ulcer rebleeding after endoscopic therapy is ~5-10%. Diverticular bleeding: 80% self-limiting but 25% recurrence.

Glasgow-Blatchford Score Components

UGIB vs LGIB Quick Reference