Overview
Lower Gastrointestinal Bleeding
Topic Overview
Summary
Lower gastrointestinal bleeding (LGIB) is bleeding from a source distal to the ligament of Treitz (small bowel, colon, or rectum). It typically presents as haematochezia (fresh red blood per rectum). Most LGIB is self-limiting, but significant bleeding requires resuscitation, risk stratification (Oakland score), blood transfusion, and endoscopic/radiological/surgical intervention. Common causes include diverticular disease, haemorrhoids, angiodysplasia, and colorectal cancer.
Key Facts
- Presentation: Haematochezia (bright red blood), maroon stool, or melaena (if slow transit)
- Common causes: Diverticular disease (30-40%), haemorrhoids, angiodysplasia, colorectal cancer, IBD
- Risk stratification: Oakland score (predicts safe discharge)
- Investigation: Colonoscopy is first-line; CT angiography if massive bleeding
- Treatment: Most self-limiting; endoscopic haemostasis, embolisation, or surgery if severe
Clinical Pearls
Most LGIB stops spontaneously — but diverticular bleeds can be massive and recurrent
Maroon stool with haemodynamic instability can indicate upper GI source — consider OGD
Haemorrhoids only cause minor self-limiting bleeding — significant LGIB is not from haemorrhoids
Why This Matters Clinically
LGIB is a common presentation. While often benign (haemorrhoids, minor diverticular bleeds), it can be life-threatening. Accurate risk stratification identifies those who can be safely discharged (Oakland score ≤8) and those requiring admission, blood products, and intervention.
Visual Summary
Visual assets to be added:
- LGIB management algorithm
- Oakland score calculator
- Colonoscopic view of diverticular bleed
- CT angiogram showing active LGIB
Epidemiology
Incidence
- Hospital admissions: 20-30 per 100,000/year
- ED presentations: Very common
- Mortality: 2-4% (lower than UGIB)
Demographics
- Age: Increases with age (diverticulosis, angiodysplasia)
- Sex: Slight male predominance
Common Causes (By Frequency)
| Cause | Percentage |
|---|---|
| Diverticular disease | 30-40% |
| Haemorrhoids | 10-20% |
| Colorectal neoplasia | 10-15% |
| Angiodysplasia | 5-10% |
| IBD (ulcerative colitis, Crohn's) | 5-10% |
| Colitis (ischaemic, infectious, radiation) | 5-10% |
| Post-polypectomy | 2-5% |
Pathophysiology
By Cause
| Cause | Mechanism |
|---|---|
| Diverticular bleed | Arterial erosion into diverticulum; usually painless, massive |
| Angiodysplasia | Venous ectasia; recurrent, often right colon |
| Haemorrhoids | Dilated venous cushions; minor bleeding, post-defecation |
| Colorectal cancer | Tumour friability, neovascularisation |
| IBD | Mucosal ulceration and inflammation |
| Ischaemic colitis | Watershed hypoperfusion → mucosal injury |
Distinguishing LGIB from UGIB
- Haematochezia usually = LGIB
- BUT: Massive UGIB with rapid transit can present as haematochezia
- If haemodynamically unstable with haematochezia → consider OGD to exclude UGIB
Clinical Presentation
Symptoms
Associated Features
| Cause | Associated Features |
|---|---|
| Diverticular | Painless; massive; often right-sided source |
| Haemorrhoids | Bright blood on paper; post-defecation; no clots |
| Cancer | Weight loss, change in bowel habit, anaemia |
| IBD | Diarrhoea, mucus, abdominal pain, extra-intestinal features |
| Ischaemic | Pain out of proportion, AF, hypotension |
Red Flags
| Feature | Significance |
|---|---|
| Haemodynamic instability | Needs urgent resuscitation, possible intervention |
| Large volume / clots | Significant bleed |
| Syncope | Significant blood loss |
| Anticoagulant use | Increases bleeding risk and severity |
| Weight loss, anaemia | Colorectal cancer until proven otherwise |
Haematochezia (fresh red blood per rectum)
Common presentation.
Maroon stool
Common presentation.
Blood on wiping / in toilet
Common presentation.
Clots (suggests more significant bleed)
Common presentation.
Abdominal pain (suggests ischaemia, IBD, or cancer)
Common presentation.
Clinical Examination
Vital Signs
- Tachycardia, hypotension (shock)
- Postural drop
Abdominal Examination
- Tenderness (ischaemia, IBD, perforation)
- Mass (cancer)
- Distension
Digital Rectal Examination
- Essential in all patients
- Assess stool colour (fresh blood, melaena, maroon)
- Masses, haemorrhoids, anal fissure
Proctoscopy
- Visualise haemorrhoids, anal canal pathology
Investigations
Immediate
| Test | Purpose |
|---|---|
| FBC | Hb (may be normal in acute bleed), MCV (chronic loss) |
| U&E | Urea:creatinine ratio elevated in UGIB |
| Coagulation | Anticoagulation, liver disease |
| Group & Save / Crossmatch | If significant bleeding |
Risk Stratification — Oakland Score (Discharge Safety)
| Factor | Points |
|---|---|
| Age | 0-2 |
| Sex (male) | 1 |
| Previous LGIB admission | 1 |
| DRE findings | 0-2 |
| Heart rate | 0-3 |
| Systolic BP | 0-4 |
| Hb | 0-22 |
Interpretation:
- Score ≤8: 95% probability of safe discharge (no transfusion, no intervention, no re-bleeding)
- Score >8: Consider admission
Imaging
| Modality | Indication |
|---|---|
| CT angiography | Active massive bleeding — localises source for embolisation/surgery |
| CT colonography | If colonoscopy not feasible |
Endoscopy
| Procedure | Role |
|---|---|
| Colonoscopy | First-line investigation; can be therapeutic |
| OGD | If UGIB not excluded (haemodynamic instability, melaena) |
| Flexible sigmoidoscopy | If distal source suspected (haemorrhoids, proctitis) |
Classification & Staging
By Severity
| Severity | Features |
|---|---|
| Minor | Haemodynamically stable, minimal bleeding, no transfusion needed |
| Moderate | Stable with ongoing bleeding, may need 1-2 units RBC |
| Severe/Massive | Unstable, shock, requiring massive transfusion, intervention |
By Aetiology
- Diverticular
- Vascular (angiodysplasia)
- Inflammatory (IBD, infectious, ischaemic)
- Neoplastic
- Anorectal (haemorrhoids, fissure)
- Post-procedural
Management
Resuscitation
- IV access (two large-bore cannulae)
- IV crystalloid if hypotensive
- Blood transfusion if Hb under 70 (or under 80 in cardiovascular disease)
- Correct coagulopathy (FFP, vitamin K if warfarin, reversal agents)
Risk Stratification
- Calculate Oakland score
- Score ≤8: Consider same-day discharge with outpatient investigation
- Score >8: Admission for observation, inpatient colonoscopy
Inpatient Colonoscopy
- Ideally within 24 hours once haemodynamically stable
- Allows diagnosis and therapy (clips, injection, thermal)
Massive LGIB
| Intervention | Indication |
|---|---|
| CT angiography | Localise bleeding source when too brisk for colonoscopy |
| Angiographic embolisation | Active arterial bleed; first-line if interventional radiology available |
| Surgery | Haemodynamically unstable despite resuscitation; failed embolisation |
Specific Treatments
| Cause | Treatment |
|---|---|
| Diverticular bleed | Usually self-limiting; colonoscopic haemostasis or embolisation if persistent |
| Angiodysplasia | Argon plasma coagulation (APC) at colonoscopy |
| Haemorrhoids | Topical treatment, banding, or surgery |
| IBD | Medical therapy (steroids, biologics) |
| Cancer | Surgical resection |
Complications
From Bleeding
- Haemorrhagic shock
- Multi-organ failure
- Death (2-4%)
From Investigation/Treatment
- Perforation (colonoscopy)
- Colonic infarction (embolisation)
- Re-bleeding (common in diverticular, angiodysplasia)
Long-Term
- Recurrent diverticular bleeding (20-40%)
- Iron deficiency anaemia
Prognosis & Outcomes
Mortality
- Overall: 2-4%
- Higher in: Elderly, anticoagulated, multiple comorbidities
Re-Bleeding
- Diverticular: 25-40% re-bleed within 4 years
- Angiodysplasia: High recurrence; may need repeat treatment
Prognosis by Oakland Score
- Score ≤8: Excellent prognosis; safe for outpatient management
Evidence & Guidelines
Key Guidelines
- BSG Guidelines on the Diagnosis and Management of Acute Lower GI Bleeding (2019)
- **NICE NG12: Suspected Cancer (2-week pathway referral)
Key Evidence
- Oakland score validated for predicting safe discharge (Lancet Gastro Hepatol, 2017)
- Early colonoscopy (under 24h) may improve outcomes in selected patients
Patient & Family Information
What is Lower GI Bleeding?
Lower GI bleeding means bleeding from the bowel or rectum. You may notice blood in your stool or on toilet paper. Most cases are not serious, but some need hospital investigation.
Common Causes
- Piles (haemorrhoids)
- Diverticular disease (small pouches in the bowel)
- Inflammatory bowel disease
- Polyps or bowel cancer
When to Seek Help
- Large amounts of blood or clots
- Feeling faint, dizzy, or unwell
- Blood mixed with stool (not just on paper)
- Change in bowel habit or weight loss
What Happens in Hospital
- Blood tests
- Possibly a camera test (colonoscopy) to find the cause
- Treatment if needed
Resources
References
Primary Guidelines
- Oakland K, et al. Diagnosis and management of acute lower gastrointestinal bleeding: guidelines from the British Society of Gastroenterology. Gut. 2019;68(5):776-789. PMID: 30792244
Key Studies
- Oakland K, et al. The Oakland Score to identify patients with lower gastrointestinal bleeding who do not need hospital admission. Lancet Gastroenterol Hepatol. 2017;2(9):635-643. PMID: 28651930
- Strate LL, Gralnek IM. ACG Clinical Guideline: Management of Patients With Acute Lower Gastrointestinal Bleeding. Am J Gastroenterol. 2016;111(4):459-474. PMID: 26925883