What is the management algorithm for lower gastrointestinal (GI) bleeding?

Management Algorithm for Lower Gastrointestinal Bleeding

Step 1: Immediate Hemodynamic Assessment and Resuscitation

Calculate the shock index (heart rate/systolic BP) immediately upon presentation—a shock index >1 indicates hemodynamic instability and dictates your entire management pathway. 1

• Unstable patients (shock index >1): Initiate aggressive IV fluid resuscitation and proceed directly to Step 2 for unstable patients 1, 2
• Stable patients: Calculate the Oakland score (age, gender, previous LGIB admission, digital rectal examination findings, heart rate, systolic BP, hemoglobin) to guide disposition 1, 2
  • Oakland score ≤8: Discharge for urgent outpatient investigation 1, 3
  • Oakland score >8: Admit for inpatient colonoscopy 2

Step 2: Rule Out Upper GI Source (Critical Step)

Before assuming lower GI bleeding, recognize that 11-15% of patients with brisk hematochezia and hemodynamic compromise actually have an upper GI source. 1, 4

• Perform upper endoscopy immediately if: 1, 4
  • Hemodynamic instability present
  • Elevated BUN/creatinine ratio
  • Antiplatelet drug use
  • Risk factors for peptic ulcer or portal hypertension

Step 3: Transfusion Strategy

Use restrictive transfusion thresholds—liberal transfusion worsens outcomes. 1, 3

• Without cardiovascular disease: Transfuse at Hb ≤70 g/L, target 70-90 g/L 1, 3
• With cardiovascular disease: Transfuse at Hb ≤80 g/L, target ≥100 g/L 1, 3

Step 4: Diagnostic Pathway Based on Hemodynamic Status

For UNSTABLE Patients (Shock Index >1):

CT angiography (CTA) is your first-line diagnostic test—NOT colonoscopy. 1, 2

1. Perform CTA immediately (fastest, least invasive localization method) 1, 2
2. If CTA positive: Proceed to catheter angiography with embolization within 60 minutes 1, 2
3. If CTA negative: Perform upper endoscopy (remember 11-15% have upper GI source) 1, 4
4. If still no source identified and patient remains unstable despite resuscitation: Surgery is indicated only after exhaustive radiologic/endoscopic attempts at localization 1, 4

Exception: Post-polypectomy bleeding—proceed directly to colonoscopy even if unstable, as the source is known 1

For STABLE Patients with Major Bleeding (Oakland >8):

Colonoscopy is your primary diagnostic and therapeutic modality. 1, 4

1. Perform colonoscopy after admission with rapid bowel preparation (improves visualization and diagnostic yield) 4, 5
2. Timing: Within 24 hours of presentation 5
3. If high-risk stigmata identified (active bleeding, visible vessel, adherent clot): Perform endoscopic hemostasis using dual modality therapy (epinephrine plus one other method—mechanical, thermal, or combination) 1, 5

Step 5: Coagulopathy and Anticoagulation Management

Correct coagulopathy immediately—delays worsen outcomes. 1, 2

Warfarin:

• Interrupt warfarin at presentation 1, 2, 3
• For unstable hemorrhage: Give prothrombin complex concentrate (PCC) + IV vitamin K 1, 3
• If PCC unavailable: Use fresh frozen plasma 3
• Restart warfarin: 7 days after hemorrhage if low thrombotic risk 2

Direct Oral Anticoagulants (DOACs):

• Temporarily withhold at presentation 3

Antiplatelet Agents:

• Aspirin for primary prevention: Permanently discontinue 1, 2
• Aspirin for secondary prevention: Do NOT stop; if stopped, restart within 5 days or as soon as hemostasis achieved 1, 3
• Dual antiplatelet therapy (aspirin + P2Y12 inhibitor): Continue aspirin; P2Y12 inhibitor can be temporarily interrupted based on bleeding severity and ischemic risk, restart within 5 days 3

Step 6: Management of Rebleeding or Persistent Bleeding

If bleeding continues or recurs despite initial endoscopic therapy: 4, 5

1. First attempt: Repeat colonoscopy with endoscopic hemostasis 5
2. If colonoscopy fails or patient too unstable: Catheter angiography with embolization 1, 4
3. Consider radionuclide scanning (99Tc-labeled RBC scan) for episodic bleeding; if positive, proceed to urgent angiography within 1 hour 4

Step 7: Surgical Intervention (Last Resort)

Surgery should only be performed after every effort to localize bleeding radiologically and endoscopically—blind surgery has 33-57% mortality. 1, 4

Indications for surgery: 1, 4

• Hemodynamic instability persists despite resuscitation
• Transfusion requirement exceeds 6 units
• Severe recurrent bleeding after failed endoscopic/radiologic intervention

Critical requirement:

• Accurate preoperative localization is mandatory 4
• Blind segmental resection or subtotal colectomy without localization has 33% rebleeding rate and 33-57% mortality 4

Risk Stratification Tools for Severe Bleeding

Use the BLEED classification to identify high-risk patients: 6, 4

• Bleeding ongoing
• Low systolic blood pressure (<115 mmHg)
• Elevated prothrombin time
• Erratic mental status
• Disease (unstable comorbid conditions)

Additional high-risk features: 6, 4

• Heart rate >100/min
• Syncope
• Nontender abdomen
• Bleeding per rectum during first 4 hours
• Aspirin use
• More than two active comorbidities
• Initial hematocrit <35%
• Gross blood on rectal examination

Key Pitfalls to Avoid

• Do NOT assume bright red rectal bleeding is always lower GI—11-15% have upper GI source, especially if unstable 1, 4
• Do NOT perform colonoscopy first in unstable patients—CTA is faster, safer, and identifies non-colonic sources 1, 2
• Do NOT delay CTA to perform colonoscopy in unstable patients 1, 2
• Do NOT perform emergency laparotomy without exhaustive localization attempts—operative mortality is 10% 1
• Do NOT use liberal transfusion strategies—restrictive thresholds improve outcomes 1, 3
• Do NOT stop aspirin for secondary cardiovascular prevention—thrombotic risk outweighs bleeding risk 1, 3

Prognosis Context

Most lower GI bleeding stops spontaneously—over 75% of diverticular bleeding resolves without intervention. 6 However, mortality is related to comorbidity rather than exsanguination: overall in-hospital mortality is 3.4%, but rises to 20% in patients requiring ≥4 units of red cells 2. Rebleeding occurs in 14-38% after the primary episode 6.