What is the initial management and diagnosis for a patient presenting with a lower gastrointestinal (GI) bleed?

Emergent Management and Diagnosis of Lower GI Bleeding

Immediate Hemodynamic Assessment

Calculate the shock index (heart rate ÷ systolic blood pressure) immediately upon presentation—a shock index >1 defines hemodynamic instability and mandates urgent intervention with CT angiography rather than colonoscopy. 1, 2

• Place at least two large-bore IV catheters and initiate aggressive fluid resuscitation with crystalloids 2
• Perform digital rectal examination to confirm blood in stool and exclude anorectal pathology 1
• Check for orthostatic hypotension, which indicates significant blood loss requiring ICU admission 1
• Obtain complete blood count, coagulation studies (PT/INR), blood type and cross-match 2

Risk Stratification for Stable Patients

For hemodynamically stable patients (shock index ≤1), calculate the Oakland score to guide disposition 1:

Oakland Score Components:

• Age: <40 years (0 points), 40-69 years (1 point), ≥70 years (2 points) 3
• Gender: female (0 points), male (1 point) 3
• Previous LGIB admission: no (0 points), yes (1 point) 3
• Digital rectal examination: no blood (0 points), blood present (1 point) 3
• Heart rate: <70 (0 points), 70-89 (1 point), 90-109 (2 points), ≥110 (3 points) 3
• Systolic BP: <90 (5 points), 90-119 (4 points), 120-129 (3 points), 130-159 (2 points), ≥160 (0 points) 3
• Hemoglobin: <70 g/L (22 points), 70-89 (17 points), 90-109 (13 points), 110-129 (8 points), 130-159 (4 points), ≥160 (0 points) 3

Oakland score ≤8 points: Safe discharge for urgent outpatient colonoscopy within 2 weeks 1, 3

Oakland score >8 points: Hospital admission for inpatient colonoscopy on next available list 1, 3

Management Algorithm Based on Hemodynamic Status

For Hemodynamically UNSTABLE Patients (Shock Index >1):

Perform CT angiography immediately as the first diagnostic test—NOT colonoscopy—as CTA provides the fastest and least invasive means to localize bleeding with 94% positive rate in unstable patients. 1, 2

• CTA must be performed in the arterial phase, not delayed/portal-venous phase 2
• Do NOT administer positive oral contrast before CTA as it masks extravasation 2
• Following positive CTA, proceed to catheter angiography with embolization within 60 minutes in centers with 24/7 interventional radiology 1, 2
• If CTA shows no lower GI source, perform upper endoscopy immediately as up to 11% of hematochezia originates from upper GI bleeding 1, 2
• Colonoscopy is explicitly contraindicated in unstable patients—it delays definitive localization and treatment 1

For Hemodynamically STABLE Patients (Shock Index ≤1):

Perform colonoscopy on the next available inpatient list (not urgently within 24 hours) after adequate bowel preparation with 4-6 liters of polyethylene glycol over 3-4 hours. 1, 4

• Urgent colonoscopy within 24 hours does not improve clinical outcomes including rebleeding, mortality, or length of stay 1
• CTA before colonoscopy in stable patients can guide localization (60% vs 31% lesion identification) but does not affect clinical outcomes 1

Transfusion Strategy

Use restrictive transfusion thresholds for most patients:

• Hemoglobin trigger 70 g/L, target 70-90 g/L for patients without cardiovascular disease 1, 4
• Hemoglobin trigger 80 g/L, target ≥100 g/L for patients with cardiovascular disease 1, 4

Anticoagulation Management

For patients on warfarin with unstable hemorrhage:

• Interrupt warfarin immediately and reverse with prothrombin complex concentrate AND vitamin K 1, 4
• Restart warfarin at 7 days after hemorrhage for patients with low thrombotic risk 1, 4

For patients on DOACs:

• Interrupt DOAC therapy immediately at presentation 1
• For life-threatening hemorrhage, administer specific reversal agents (idarucizumab for dabigatran, andexanet for anti-factor Xa inhibitors) 1
• Restart DOAC at maximum 7 days after hemorrhage 1

Antiplatelet Management

For patients on aspirin:

• Permanently discontinue aspirin for primary prophylaxis 1
• Do NOT stop aspirin for secondary cardiovascular prevention—if stopped, restart as soon as hemostasis is achieved 1, 4

For patients on dual antiplatelet therapy:

• Continue aspirin 4
• P2Y12 receptor antagonist can be continued or temporarily interrupted based on bleeding severity and ischemic risk 4
• If interrupted, restart P2Y12 receptor antagonist within 5 days 4

Coagulopathy Correction

Correct coagulopathy immediately if present:

• Transfuse fresh frozen plasma for INR >1.5 1
• Transfuse platelets for platelet count <50,000/µL 1

ICU Admission Criteria

Admit to ICU if any of the following are present 1:

• Orthostatic hypotension
• Hematocrit decrease ≥6%
• Transfusion requirement >2 units packed red blood cells
• Continuous active bleeding
• Persistent hemodynamic instability despite aggressive resuscitation

Critical Pitfalls to Avoid

• Do not perform colonoscopy in unstable patients—this delays CTA and potential life-saving embolization 1, 2
• Always consider upper GI source in unstable patients—failure to do so leads to delayed diagnosis and treatment 1, 2
• Do not rush to surgery without localization attempts—blind segmental resection has 33% rebleeding rate and 33-57% mortality 1
• Do not perform colonoscopy without adequate bowel preparation—poor preparation leads to missed lesions and repeat procedures 1

Mortality Context

Mortality in lower GI bleeding is generally related to comorbidity rather than exsanguination, with overall in-hospital mortality of 3.4%, rising to 18% for inpatient-onset LGIB and 20% for patients requiring ≥4 units of red blood cells 1