Lower Gastrointestinal Bleeding: Clinical Presentation and Management
Clinical Presentation
Lower GI bleeding typically presents as bright or dark red blood per rectum (hematochezia), blood clots per rectum, or blood mixed with stool. 1
Key Clinical Features to Assess
- Hemodynamic parameters: Measure shock index (heart rate/systolic BP), with shock index >1 indicating hemodynamic instability 2
- Digital rectal examination findings: Confirm blood in stool and exclude anorectal pathology 2, 3
- Vital sign abnormalities: Systolic BP <100 mmHg or heart rate >100/min within 1 hour of evaluation predict severe bleeding 1
- Gross blood on initial rectal examination is an independent risk factor for severe bleeding 1
- Orthostatic hypotension indicates significant blood loss requiring ICU admission 2
- Syncope correlates with severe bleeding 1
Important Differential Consideration
10-15% of patients presenting with severe hematochezia have an upper GI source, particularly those with hemodynamic instability, history of peptic ulcer disease, or portal hypertension 2, 3. Nasogastric tube placement is only appropriate when an upper GI source is suspected; maroon-colored stool strongly suggests a lower GI origin 2.
Initial Risk Stratification
Oakland Score for Stable Patients
For hemodynamically stable patients, calculate the Oakland score (includes age, gender, previous LGIB admission, digital rectal examination findings, heart rate, systolic BP, and hemoglobin) to guide disposition. 2
- Oakland score ≤8 points: Discharge for urgent outpatient colonoscopy within 2 weeks (6% have underlying bowel cancer) 2, 4
- Oakland score >8 points: Admit for inpatient colonoscopy on next available list 2, 4
High-Risk Features Predicting Severe Bleeding
- Initial hematocrit <35% 1
- Heart rate >100/min or systolic BP <115 mmHg 1
- Aspirin use 1
- More than two active comorbid conditions 1
- Bleeding per rectum during first 4 hours of evaluation 1
Immediate Resuscitation
Fluid and Blood Product Management
For clinically stable patients without cardiovascular disease, use restrictive transfusion thresholds with hemoglobin trigger of 7 g/dL and target 7-9 g/dL. 2, 4
For patients with cardiovascular disease, use hemoglobin trigger of 8 g/dL and target ≥10 g/dL. 2, 4
Coagulopathy Correction
Correct coagulopathy immediately: transfuse fresh frozen plasma for INR >1.5 and platelets for platelet count <50,000/µL. 2, 3
Anticoagulation and Antiplatelet Management
Warfarin Management
For patients on warfarin with unstable hemorrhage, interrupt warfarin immediately and reverse with 4-factor prothrombin complex concentrate (PCC) plus low-dose vitamin K (<5 mg). 2, 4 Do not use fresh frozen plasma as first-line; it requires ABO matching, has slower infusion, and increases volume overload risk 2.
Restart warfarin at 7 days after hemostasis for patients with low thrombotic risk. 2, 4 For high thrombotic risk (mechanical mitral valve, recent VTE within 3 months), consider bridging with low-molecular-weight heparin at 48 hours after stable hemostasis 2.
Direct Oral Anticoagulant (DOAC) Management
Interrupt DOAC therapy immediately at presentation. 2 For life-threatening hemorrhage, administer specific reversal agents: idarucizumab for dabigatran, andexanet for anti-factor Xa inhibitors 2. Restart DOAC at maximum 7 days after hemorrhage 2.
Antiplatelet Management
For aspirin used for primary prophylaxis, permanently discontinue it. 2, 4
For aspirin used for secondary cardiovascular prevention, do not routinely stop it; if stopped, restart as soon as hemostasis is achieved (preferably within 5 days). 2, 4
For dual antiplatelet therapy (aspirin plus P2Y12 inhibitor), continue aspirin; the P2Y12 inhibitor can be continued or temporarily interrupted according to bleeding severity and ischemic risk, but restart within 5 days if interrupted. 4
Diagnostic Algorithm Based on Hemodynamic Status
Hemodynamically Unstable Patients (Shock Index >1)
CT angiography (CTA) should be performed immediately as the first diagnostic test, NOT colonoscopy. 1, 2 CTA provides the fastest and least invasive means to localize bleeding, with 94% sensitivity in unstable patients and ability to detect bleeding rates as low as 0.3 mL/min 1, 2.
Following positive CTA, catheter angiography with embolization should be performed within 60 minutes to maximize success rates. 1, 2 Transcatheter embolization achieves immediate hemostasis in 40-100% of cases 2.
If CTA identifies no lower GI source, perform upper endoscopy before any surgical intervention, as up to 15% of severe hematochezia originates from the upper GI tract 1, 2.
Colonoscopy is contraindicated in hemodynamically unstable patients because it requires adequate bowel preparation (4-6 L polyethylene glycol over 3-4 hours) which is not feasible, and urgent colonoscopy does not improve rebleeding, mortality, or length of stay 1, 2.
Hemodynamically Stable Patients
For stable patients, colonoscopy on the next available inpatient list (not urgently within 24 hours) is recommended, as urgent colonoscopy does not improve clinical outcomes including rebleeding, mortality, or length of stay 1, 2, 4.
Colonoscopy after rapid bowel cleansing has diagnostic accuracy of 72-86% and is the procedure of choice for acute lower GI bleeding in stable patients 3, 5.
Consider upper endoscopy early in stable patients with risk factors for peptic ulcer, portal hypertension, or angiodysplasia. 3
Endoscopic Therapy
Diverticular Bleeding
Endoscopic stigmata of recent bleeding (visible vessel or adherent clot) reliably predict severe diverticular hemorrhage, while clean-based ulcer within a diverticulum indicates low rebleeding risk 1.
Postpolypectomy Bleeding
Early postpolypectomy bleeding (at time of polypectomy) can be controlled by resnaring the polyp stalk and applying pressure. 1 For delayed bleeding (up to 15 days post-procedure), which resolves spontaneously in >70% of cases, persistent bleeding can be managed with loop ligation, band ligation, adrenaline injection followed by thermal therapy, or endovascular clipping 1.
Angiodysplasia
Treat colonic angiodysplasia with injection of 1:10,000 adrenaline prior to endoscopic coagulation with bipolar or heater probe. 1 Extra care must be taken when treating cecal lesions to avoid perforation 1.
Radiation Proctitis
For chronic rectal bleeding from radiation proctitis, heater probe or bipolar electrocoagulation are equally effective, with both reducing severe bleeding and improving patient symptoms at 6 months 1.
Surgical Indications
Surgery is reserved as a last resort and indicated only when the patient remains unstable despite successful localization and endovascular therapy, or after failure of angiographic embolization. 2
Blind segmental resection or emergency subtotal colectomy without prior localization carries rebleeding rates up to 33% and mortality 33-57%. 2 Emergency total colectomy mortality is 27-33% versus ~10% when bleeding is first localized 2.
Diagnostic laparotomy is mandatory only after failure of all non-operative localization methods and persistent hemodynamic instability despite aggressive resuscitation. 2
Alternative Diagnostic Modalities
Radionuclide Imaging
[99Tcm] pertechnetate-labeled red blood cell scanning detects bleeding at rates of 0.1-0.5 mL/min and is more sensitive than angiography but less specific 3. It is preferred for evaluation of episodic lower GI bleeding 3. A positive red blood cell scan should be followed by urgent angiography within 1 hour. 3
Small Bowel Evaluation
If bleeding source not identified after upper endoscopy and colonoscopy, evaluate small bowel with enteroscopy or video capsule endoscopy. 3
ICU Admission Criteria
Admit to ICU if: 2
- Orthostatic hypotension present
- Hematocrit decrease ≥6%
- Transfusion requirement >2 units packed red blood cells
- Continuous active bleeding
- Persistent hemodynamic instability despite aggressive resuscitation
Common Pitfalls to Avoid
- Never rush to colonoscopy in unstable patients – this delays definitive localization with CTA and potential embolization 1, 2
- Do not use fresh frozen plasma as first-line warfarin reversal – PCC is faster, does not require ABO matching, and avoids volume overload 2
- Do not perform colonoscopy without adequate bowel preparation – poor preparation leads to missed lesions and need for repeat procedures 2
- Do not assume bright red blood per rectum is always a lower GI source – up to 15% may be from upper GI bleeding 1, 2
- Do not forget anorectal examination – benign anorectal conditions account for 16.7% of diagnoses 2
- Do not perform blind segmental resection – localize bleeding first with CTA or angiography to avoid 33-57% mortality 2
Organizational Requirements
All hospitals routinely admitting GI bleeding patients must have: 2
- Designated GI bleeding lead clinician responsible for integrated care pathways
- Access to 7/7 on-site colonoscopy with endoscopic therapy capabilities
- Access to 24/7 interventional radiology either on-site or via formalized referral pathway