Lower GI bleed: workup and management
Acute lower GI bleeding presents with hematochezia. Resuscitate, exclude an upper GI source in hemodynamically unstable patients, risk-stratify (e.g., Oakland score), and arrange colonoscopy after bowel prep. CT angiography is the first test for ongoing brisk bleeding.
Working diagnosis
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- ACG 2023 guideline: urgent colonoscopy within 24 hours is no longer routine; trials showed no benefit, so use the next available inpatient slot
- CT angiography first for hemodynamically unstable hematochezia; refer positive scans promptly for embolization
- Reverse anticoagulation only for life-threatening bleeding that does not respond to resuscitation; resume anticoagulation, usually within 7 days
- Oakland score ≤8 supports discharge with outpatient evaluation
Differential diagnoses
- Diverticular bleeding
- Brisk upper GI bleed (can't miss: 10–15% of severe hematochezia)
- Angiodysplasia
- Ischemic colitis
- Colorectal cancer or polyp, post-polypectomy bleed
- Hemorrhoids or anal fissure
- Inflammatory or infectious colitis
02Assess
Risk scores and decision tools
- Oakland score (≤8: safe for discharge)
- Shock index (HR/SBP >1 suggests significant bleeding)
- BUN:creatinine ratio >30 suggests an upper source
Key history questions
- Volume, color and frequency of bleeding; syncope
- Antiplatelets, anticoagulants, NSAIDs
- Recent polypectomy, prior diverticular bleeding
- Weight loss, change in bowel habit
- Abdominal pain (ischemia, colitis)
- Cardiovascular disease and cirrhosis
Examination findings
- Heart rate, blood pressure, orthostatics
- Abdominal tenderness
- Digital rectal exam and anoscopy for blood, masses, hemorrhoids
03Investigate
Initial investigations
- CBC, BMP (BUN:creatinine ratio >30 suggests upper source), INR
- Type and screen or crossmatch
- Oakland score for discharge decisions
Advanced investigations
- Colonoscopy after bowel preparation at the next available inpatient slot; urgent (<24 h) colonoscopy has not improved outcomes
- CT angiography first for ongoing hemodynamically significant bleeding, then catheter angiography and embolization
- Upper endoscopy for hemodynamic instability or high BUN ratio
04Treat
Immediate management
- Two large-bore IVs and crystalloid
- Transfuse to hemoglobin ≥7 g/dL (≥8 g/dL with cardiovascular disease)
- Hold anticoagulants; reverse for life-threatening bleeding
- Unstable with suspected ongoing bleeding: CT angiography first
First-line treatment
- Colonoscopy with endoscopic hemostasis (clips, epinephrine, thermal)
- Continue aspirin for secondary cardiovascular prevention when possible
- Stop NSAIDs
Second-line treatment
- Angiographic embolization for bleeding seen on CTA
- Surgery for refractory bleeding after localization
Specialist referrals
- Gastroenterology
- Interventional radiology for positive CTA
- Colorectal surgery for refractory bleeding
05Disposition
Admission criteria
- Oakland score >8
- Hemodynamic instability, ongoing bleeding, transfusion need
- Anticoagulation or significant comorbidity
Safe discharge criteria
- Oakland score ≤8 with stable vitals and hemoglobin
- Outpatient colonoscopy arranged
Follow-up timing
- Repeat CBC within 1 week; outpatient colonoscopy if not done
Patient instructions
- Avoid NSAIDs
- Return for further bleeding, dizziness or fainting
Monitoring
- Serial hemoglobin every 6–12 hours initially
- Vital signs
Clinical pearls and pitfalls
- Most diverticular bleeding stops spontaneously but recurs in up to 20–40%
- Restart anticoagulation once hemostasis is achieved, after weighing thrombotic risk
RefGuidelines and landmark evidence
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.