What is the approach to managing a patient with hematochezia (blood in stools)?

Approach to Blood in Stools (Hematochezia)

Immediate Hemodynamic Assessment

The first critical step is to determine hemodynamic stability using the shock index (heart rate/systolic BP), with a value >1 defining instability and dictating an entirely different diagnostic pathway. 1, 2

• Check vital signs immediately, measure hemoglobin/hematocrit, and assess coagulation parameters to evaluate bleeding severity 1, 2
• For severe bleeding, perform blood typing and cross-matching 1, 2
• Calculate the shock index: values >1 indicate hemodynamic instability requiring urgent intervention 1

Algorithmic Approach Based on Stability

For Hemodynamically UNSTABLE Patients (Shock Index >1):

CT angiography should be performed FIRST—not endoscopy—as it provides the fastest, least invasive means to localize bleeding before planning intervention. 1, 2

• Initiate aggressive IV fluid and blood product resuscitation to normalize blood pressure and heart rate 1, 2
• Maintain hemoglobin >7 g/dL (use 9 g/dL threshold for massive bleeding or cardiovascular comorbidities) 1, 2
• Perform CT angiography immediately, which can detect bleeding at rates as low as 0.3 mL/min 1, 2
• If CTA is negative, perform upper endoscopy immediately, as up to 15% of patients with hematochezia have an upper GI source 1
• Catheter angiography with embolization should follow positive CTA within 60 minutes in centers with 24/7 interventional radiology 1

For Hemodynamically STABLE Patients:

Begin with anoscopy/proctoscopy to identify common anorectal causes, followed by colonoscopy for those requiring hospital admission. 1, 2

Risk Stratification:

• Use the Oakland score to categorize bleeding severity 1, 2
• Patients with Oakland score ≤8 points (minor self-terminating bleed) can be discharged for urgent outpatient investigation 1
• Patients with major bleeding (Oakland score >8) require hospital admission for colonoscopy 1

Diagnostic Sequence:

• Perform anoscopy or proctoscopy first to identify hemorrhoids, fissures, or anorectal varices 1, 2
• Upper and lower GI endoscopy should be the initial diagnostic procedures for stable patients with major bleeding 1
• Consider upper endoscopy early if no clear anorectal source is identified, as rapid upper GI bleeding can present as hematochezia 1

Key Diagnostic Considerations

When to Perform Upper Endoscopy:

• Always perform upper endoscopy if initial lower tract evaluation is negative, as 8-15% of hematochezia cases originate from upper GI sources 1
• Prioritize upper endoscopy in patients with hemodynamic instability after negative CTA 1

Role of Advanced Imaging:

• Contrast-enhanced CT before colonoscopy improves detection rates for vascular lesions (35.7% vs 20.6%) 1, 2
• Nuclear medicine studies can be used for intermittent or slow bleeding when endoscopy is negative 2
• Angiography requires bleeding rates >0.5 mL/min to localize the source 1

Resuscitation Targets

Use restrictive transfusion thresholds: hemoglobin trigger of 70 g/dL (target 70-90 g/dL), or 80 g/dL trigger (target 100 g/dL) for patients with cardiovascular disease. 1

• Avoid fluid overload while maintaining mean arterial pressure >65 mmHg 1
• Interrupt warfarin therapy at presentation; reverse with prothrombin complex concentrate if unstable 1

Indications for Surgical Intervention

No patient should proceed to emergency laparotomy unless every effort has been made to localize bleeding by radiological and/or endoscopic modalities. 1

Surgery is indicated for: 1

• Persistent hemodynamic instability despite resuscitation
• Transfusion requirement >6 units of packed red blood cells
• Free perforation with pneumoperitoneum
• Massive hemorrhage with increasing transfusion requirements

Critical Pitfalls to Avoid

• Never delay CTA in unstable patients—perform it before endoscopy 1, 2
• Do not assume a lower GI source without excluding upper GI bleeding, especially in unstable patients 1
• Do not perform colonoscopy in unstable patients without first localizing the bleeding source 1
• Avoid prophylactic treatment of asymptomatic anorectal varices, as there is no supporting evidence 1