What is the appropriate management for a patient presenting with lower GI bleeding?

Management of Lower Gastrointestinal Bleeding

For hemodynamically unstable patients (shock index >1), perform CT angiography immediately as the first diagnostic test, followed by catheter angiography with embolization within 60 minutes; for hemodynamically stable patients, perform colonoscopy within 24 hours after adequate bowel preparation. 1, 2

Initial Assessment and Hemodynamic Stabilization

Calculate the shock index (heart rate ÷ systolic blood pressure) immediately upon presentation—a value >1 defines hemodynamic instability and mandates urgent intervention rather than routine colonoscopy. 3, 4

Resuscitation Protocol

• Place at least two large-bore IV catheters and initiate crystalloid resuscitation to restore hemodynamic stability. 3
• Use restrictive transfusion thresholds: hemoglobin trigger of 7 g/dL with target 7-9 g/dL for patients without cardiovascular disease. 3, 2
• Use higher transfusion thresholds: hemoglobin trigger of 8 g/dL with target ≥10 g/dL for patients with cardiovascular disease. 3, 2
• Perform digital rectal examination to confirm blood in stool and exclude anorectal pathology. 2, 4
• Always consider an upper GI source in hemodynamically unstable patients, even with bright red rectal bleeding—up to 11% may be from upper GI bleeding. 3, 4

Management Based on Hemodynamic Status

Hemodynamically Unstable Patients (Shock Index >1)

Do NOT perform colonoscopy in unstable patients—this is explicitly contraindicated and delays definitive localization. 4, 1

Diagnostic Algorithm:

1. CT angiography (CTA) immediately as the first diagnostic test—it provides 94% positive rate in unstable patients and is the fastest, least invasive means to localize bleeding. 1, 4

   • Perform arterial phase imaging (not delayed/portal-venous phase). 3
   • Do not administer positive oral contrast before CTA as it masks extravasation. 3

2. Following positive CTA: Proceed to catheter angiography with embolization within 60 minutes in centers with 24/7 interventional radiology. 1, 4

   • Transcatheter embolization provides time to stabilize the patient and prepare the bowel, contributing to better surgical outcomes if surgery becomes necessary. 1, 4

3. If no lower GI source identified: Perform upper endoscopy as hemodynamic instability may indicate an upper GI source. 3, 4

4. Surgery: Reserved only for patients who fail angiographic intervention or continue to deteriorate despite all attempts at localization and intervention. 1, 4

   • Blind segmental resection carries 33% rebleeding rates and 33-57% mortality. 4
   • Even in unstable patients, attempt localization before surgery to allow targeted treatment rather than blind resection. 1, 4

Hemodynamically Stable Patients

Risk Stratification:

Calculate the Oakland score (includes age, gender, previous LGIB admission, digital rectal examination findings, heart rate, systolic blood pressure, and hemoglobin). 3, 4

• Oakland score ≤8 points: Discharge for urgent outpatient colonoscopy within 2 weeks (as 6% have underlying bowel cancer). 4, 2
• Oakland score >8 points: Admit for inpatient colonoscopy on the next available list. 4, 2

Colonoscopy Timing:

Perform colonoscopy within 24 hours after adequate bowel preparation using 4-6 liters of polyethylene glycol over 3-4 hours. 3, 2, 5

• There is no high-quality evidence that urgent colonoscopy (<24 hours) improves clinical outcomes including rebleeding, mortality, or length of stay compared to colonoscopy on the next available list. 2, 4
• Adequate bowel preparation is essential—poor preparation leads to missed lesions and need for repeat procedures. 4

Endoscopic Hemostasis:

Provide endoscopic hemostasis therapy to patients with high-risk stigmata including active bleeding, non-bleeding visible vessel, or adherent clot. 5

• Use two modalities for hemostasis (epinephrine plus one other method) for optimal results. 3
• The specific modality (mechanical, thermal, injection, or combination) is guided by bleeding etiology, access to the bleeding site, and endoscopist experience. 5

Management of Anticoagulation and Antiplatelet Therapy

Warfarin:

• Interrupt warfarin immediately at presentation. 2, 4
• For unstable hemorrhage: Reverse with prothrombin complex concentrate AND vitamin K. 3, 2
• For patients with low thrombotic risk: Restart warfarin 7 days after hemorrhage. 3, 2

Direct Oral Anticoagulants (DOACs):

• Interrupt DOAC therapy immediately at presentation. 4
• For life-threatening hemorrhage: Administer specific reversal agents (idarucizumab for dabigatran, andexanet for anti-factor Xa inhibitors). 4
• Restart DOAC at maximum 7 days after hemorrhage. 4

Aspirin:

• For primary prophylaxis: Permanently discontinue aspirin. 3, 4
• For secondary prevention: Do NOT routinely stop aspirin; if stopped, restart as soon as hemostasis is achieved. 3, 2

Dual Antiplatelet Therapy:

• Continue aspirin; the P2Y12 receptor antagonist can be continued or temporarily interrupted according to bleeding severity and ischemic risk. 2
• If interrupted, restart the P2Y12 receptor antagonist within 5 days. 2, 4

Management of Ongoing or Recurrent Bleeding

After Initial Colonoscopy:

• Repeat colonoscopy with alternative hemostatic techniques if similar expertise is available. 1, 5
• Transcatheter embolization if colonoscopic intervention is unlikely to be effective or unavailable. 1
• Surgery reserved for when repeat colonoscopy or transcatheter embolization are not feasible, unavailable, or unlikely to be effective (e.g., tumor). 1

After Initial Angiography:

• If patient rebleeds and remains hemodynamically stable: Consider CTA to triage toward appropriate repeat intervention. 1
• If patient rebleeds and is hemodynamically unstable: Choice between repeat colonoscopy, surgery, or repeat embolization depends on the lesion and clinical scenario. 1

Alternative Diagnostic Modalities

When Colonoscopy and CTA are Negative:

• Nuclear medicine RBC scan: Can detect bleeding rates as low as 0.05-0.1 mL/min, with 60-93% sensitivity for intermittent or slow bleeding. 3
• Video capsule endoscopy: Ideally within 48 hours for obscure GI bleeding, with 87-91.9% diagnostic yield. 3
• SPECT/CT imaging: Improves localization accuracy to 75-100% compared to planar imaging alone. 3

Critical Pitfalls to Avoid

• Do not rush to colonoscopy in unstable patients—this delays definitive localization with CTA and potential embolization. 4
• Do not assume bright red blood per rectum is always a lower GI source—always consider upper GI bleeding in unstable patients. 3, 4
• Do not perform colonoscopy without adequate bowel preparation—this leads to missed lesions and repeat procedures. 4
• Do not forget anorectal examination—benign anorectal conditions account for 16.7% of diagnoses. 4

Mortality Context

Mortality in lower GI bleeding is generally related to comorbidity rather than exsanguination, with overall in-hospital mortality of 3.4%, but this rises to 18% for inpatient-onset LGIB and 20% for patients requiring ≥4 units of red cells. 3, 4