START: Acute lower GI bleeding (adult)
Haematochezia or maroon stool, suspected colorectal source. Adults only.
All Pathways
Emergency MedicineEmergency
Lower GI Bleeding Management (ACG 2023)
Lower GI Bleeding Management (ACG 2023): START: Acute lower GI bleeding (adult) → Assess and resuscitate at the same time → On anticoagulant or antiplat...
Pathway Overview
21 steps
Algorithm Steps
21 total
01Start 02Action Assess and resuscitate at the same time
History, examination and bloods to judge severity and likely source
- Two large-bore IV cannulas; IV fluid to restore BP and heart rate before any endoscopy
- FBC, UEC, coagulation, LFTs, group and crossmatch
- Do not give tranexamic acid (no benefit in LGIB)
- Stable patient: transfuse red cells if Hb below 70 g/L (consider below 80 g/L with cardiovascular disease)
- Platelets: in severe bleeding keep count above 30 x 10^9/L (above 50 x 10^9/L if endoscopic therapy); no routine platelet transfusion for antiplatelet use
- Rectal examination: confirm blood, look for an anorectal source
- History: anticoagulants, antiplatelets, NSAIDs, previous bleeding, liver disease, recent polypectomy
03Warning On anticoagulant or antiplatelet? Act before endoscopy
Stop NSAIDs. Severe bleeding: hold anticoagulant and non-aspirin antiplatelets (e.g. clopidogrel). Reverse only for life-threatening bleeding.
- Keep aspirin taken for secondary cardiovascular prevention. Coronary stent within 1 year: get cardiology advice before holding any antiplatelet
- Life-threatening bleeding on warfarin (INR 1.5 or more): 4-factor prothrombin complex concentrate (Beriplex in Australia) plus IV vitamin K, not FFP; dose per local protocol
- Life-threatening bleeding on a DOAC taken within 24 h, not controlled by resuscitation: dabigatran - idarucizumab. Apixaban or rivaroxaban: andexanet alfa is not registered in Australia; get urgent haematology advice
04Decision Haemodynamically unstable or ongoing heavy bleeding?
Yes: signs of shock (e.g. SBP below 90 mmHg, shock index HR/SBP 1 or more) or continuing heavy haematochezia. Beta-blockers can mask tachycardia: judge on BP, Hb trend and clinical picture
- If Yes
05Warning Unstable: resuscitate, then CT angiography first
No bowel prep and no urgent colonoscopy while unstable. No CT angiography or interventional radiology on site: resuscitate and arrange early transfer
- Transfuse red cells on clinical grounds; activate the massive transfusion protocol if bleeding is critical
- High suspicion of upper GI source (e.g. raised urea, liver disease): urgent gastroscopy first; NG aspirate cannot exclude it
- CT angiography is the first test while bleeding continues; alert radiology early
06Decision CT angiography shows active bleeding (contrast extravasation)?
Positive CTA: prompt interventional radiology. Negative CTA: bleeding has usually stopped.
- If Yes
07Action CTA positive: urgent catheter angiography and embolisation
Refer to interventional radiology at once
- Extravasation in the upper GI tract: urgent gastroscopy instead
- Centres with endoscopic haemostasis expertise: colonoscopy after a positive CTA is an alternative
- Embolisation fails or is not available and bleeding continues: urgent surgical review
- After embolisation: watch for rebleeding and bowel ischaemia; colonoscopy when stable to find the cause
08Action Bowel preparation before inpatient colonoscopy
Stable patients only. Good prep improves diagnostic yield.
- PEG-based prep: 4 to 6 L (historical standard), or split-dose or low-volume prep
- Nasogastric tube for prep only with caution in patients at risk of aspiration
- No unprepared colonoscopy or routine flexible sigmoidoscopy, unless the source is anorectal or distal colon
09Action Colonoscopy: find and treat the source
Inspect on insertion and withdrawal
- Wash away stool and blood; use a clear cap
- No colonic source: intubate the terminal ileum
- On anticoagulant: endoscopic haemostasis is safe with INR 2.5 or less; do not delay colonoscopy for full reversal
- Common causes: diverticula, angioectasia, ischaemic colitis, haemorrhoids, neoplasia, post-polypectomy bleeding, colitis
10Decision Active bleeding or stigmata of recent haemorrhage?
Stigmata: active bleeding, non-bleeding visible vessel or adherent clot
- If Yes
11Action Active bleeding or stigmata: endoscopic haemostasis
Treat whatever the cause
- Diverticular bleeding: through-the-scope clips, band ligation or coagulation
- Angioectasia: argon plasma coagulation
- Post-polypectomy bleeding: treat active bleeding or stigmata at the polypectomy site
- Mark the site with a tattoo if surgery may be needed
12Decision Bleeding continues or recurs?
Ongoing bleeding after endoscopic therapy, or rebleeding after it stopped: fresh haematochezia, falling Hb or instability
- If Yes
13Warning Ongoing or recurrent bleeding: CTA or repeat colonoscopy, by stability
Includes failed endoscopic haemostasis. Surgery only if endoscopic and radiological treatment fail
- Unstable or ongoing heavy bleeding: CT angiography, then embolisation if positive
- Stable with known source: repeat colonoscopy and endoscopic therapy can be considered
- Stable, suspected recurrent diverticular bleed, recent colonoscopy: observation can be considered
14Outcome Bleeding controlled: monitored bed, then antithrombotic plan
Monitor until bleeding stops. Then complete the step 'Bleeding stopped: plan antithrombotics before discharge'. Recurs despite treatment: surgical review.
If No15Action Bleeding stopped: plan antithrombotics before discharge
Stopping cardiac aspirin or anticoagulants raises the risk of MI, stroke and death
- Aspirin for secondary cardiovascular prevention: continue. Aspirin for primary prevention only: stop
- Resume anticoagulant once bleeding has stopped, usually within 7 days; agree timing with the treating team
- P2Y12 inhibitor (e.g. clopidogrel): decide with cardiology
- Stop non-aspirin NSAIDs
- Treat the cause; GI follow-up
16Outcome Discharge
Antithrombotic plan, cause and follow-up in place. Return at once if bleeding recurs.
If No17Action No stigmata: treat the cause found, or look further
No lesion needs endoscopic therapy
- Cause found (e.g. diverticulosis, haemorrhoids, colitis, neoplasia): manage the cause
- No source and bleeding continues: gastroscopy if not done; CT angiography
- Suspected small-bowel source: small-bowel bleeding workup (not covered here)
- Path rejoins step 12Shared downstream outcome
If No18Action CTA negative: observe, then non-urgent inpatient colonoscopy
Most patients settle without intervention
- No immediate catheter angiography after a negative CTA
- Bleeding restarts with instability: repeat CT angiography (see unstable step)
- Path rejoins step 08Shared downstream outcome
If No19Decision Stable: Oakland score 8 or less?
Oakland score: age, sex, previous LGIB, rectal examination, heart rate, SBP, Hb. Use with clinical judgement.
- If Yes
20Action Oakland 8 or less: consider early discharge and outpatient colonoscopy
Low risk of needing a hospital intervention; clinical judgement still applies
- Arrange outpatient colonoscopy
- Minor bleeding: oral anticoagulant may be continued if needed
- Return at once if bleeding recurs or if dizzy or faint
- Path rejoins step 15Shared downstream outcome
If No21Action Oakland above 8: admit for non-urgent inpatient colonoscopy
Next available list after bowel prep. Urgent colonoscopy within 24 h does not improve rebleeding or mortality.
- Hold oral anticoagulant on admission
- Colonoscopy may not be needed if bleeding has stopped and a high-quality colonoscopy within 12 months showed only diverticulosis
- Deteriorates or becomes unstable: go to the unstable step (CT angiography first)
- Path rejoins step 08Shared downstream outcome
Guideline Source
Management of Patients With Acute Lower Gastrointestinal Bleeding: An Updated ACG Guideline (Sengupta N et al., Am J Gastroenterol 2023;118:208-231)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults with a suspected colorectal source only; small-bowel bleeding and haemorrhoid treatment are not covered
- Reversal agents, doses and transfusion follow local protocols; no doses are given here
- Oakland score supports but does not replace clinical judgement
- Timing of anticoagulant restart after bleeding is uncertain; individualise with the treating team
Contraindicated Populations
pediatricchildren under 18 years
Applicable Regions
AUUSEUGlobal
AU: Hb in g/L (70 g/L = 7 g/dL). Australia's prothrombin complex concentrate changed from 3-factor Prothrombinex-VF to 4-factor Beriplex (NBA, 2024); warfarin reversal per MJA 2025 update and local protocol. Andexanet alfa is not on the ARTG.
US: ACG 2023 is the current US guideline
Global: Based on ACG 2023 (Sengupta et al.)
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Lower GI Bleeding Management (ACG 2023)?
The Lower GI Bleeding Management (ACG 2023) is a emergency clinical algorithm for Emergency Medicine. It provides a structured decision tree to guide clinical decision-making, based on Management of Patients With Acute Lower Gastrointestinal Bleeding: An Updated ACG Guideline (Sengupta N et al., Am J Gastroenterol 2023;118:208-231).
What guideline is the Lower GI Bleeding Management (ACG 2023) based on?
This algorithm is based on Management of Patients With Acute Lower Gastrointestinal Bleeding: An Updated ACG Guideline (Sengupta N et al., Am J Gastroenterol 2023;118:208-231) (DOI: 10.14309/ajg.0000000000002130).
What are the limitations of the Lower GI Bleeding Management (ACG 2023)?
Known limitations include: Adults with a suspected colorectal source only; small-bowel bleeding and haemorrhoid treatment are not covered; Reversal agents, doses and transfusion follow local protocols; no doses are given here; Oakland score supports but does not replace clinical judgement; Timing of anticoagulant restart after bleeding is uncertain; individualise with the treating team. Individual patient factors may require deviation from these recommendations.
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