What is the initial work-up for a patient presenting with hematochezia (blood in stool)?

Initial Work-up for Hematochezia (Blood in Stool)

The initial work-up for a patient presenting with hematochezia should include a focused medical history, complete physical examination including digital rectal examination, assessment of vital signs, hemoglobin/hematocrit determination, and coagulation studies, followed by anoscopy or flexible sigmoidoscopy as the first-line diagnostic tool. 1, 2

Initial Assessment

Clinical Evaluation

• Calculate shock index (heart rate/systolic blood pressure) to assess hemodynamic stability
  • Shock index >1 indicates instability 2
• Perform digital rectal examination to rule out anorectal causes 1
• Assess severity of bleeding:
  • Vital signs (blood pressure, heart rate)
  • Hemodynamic stability
  • Visible blood volume and characteristics (bright red vs. dark)

Laboratory Tests

• Complete blood count (CBC) with hemoglobin and hematocrit
• Coagulation profile (PT, aPTT)
• Blood typing and cross-matching (for severe bleeding) 1, 2
• Serum electrolytes, BUN, creatinine
• Serum lactate and base deficit (to estimate shock severity) 2

Diagnostic Approach Based on Severity

For Hemodynamically Unstable Patients

1. Immediate resuscitation with IV fluids
2. Blood transfusion (restrictive strategy with hemoglobin threshold of 70 g/L for most patients; 80 g/L for patients with cardiovascular disease) 2
3. CT angiography as the fastest method to localize bleeding (can detect bleeding at rates of 0.3-1.0 mL/min) 2
4. Consider immediate upper endoscopy to rule out upper GI source if CT is inconclusive

For Hemodynamically Stable Patients

1. Anoscopy or flexible sigmoidoscopy as first-line diagnostic tool 1
2. Full colonoscopy within 24 hours after adequate bowel preparation if:
   • Patient has high-risk features
   • Evidence of ongoing bleeding
   • Risk factors for colorectal cancer
   • Suspicion of more proximal bleeding source 1, 2

Special Considerations

Age-Based Approach

• Patients <30 years: Hemorrhoids are the most common cause (consider limited evaluation) 3
• Patients 30-39 years: Higher incidence of polyps (7.4%), with 28% located in proximal colon 3
• Patients >50 years: Higher risk of colorectal cancer; full colonoscopy recommended 2

Common Causes of Hematochezia

• Hemorrhoids (most common in young adults)
• Diverticular disease
• Angiodysplasia
• Ischemic colitis
• Inflammatory bowel disease
• Colorectal cancer (found in 6% of patients with rectal bleeding) 2

Pitfalls and Caveats

1. Don't assume all rectal bleeding in young patients is from hemorrhoids

   • While hemorrhoids are the most common cause, colorectal cancer can occur in young patients 4, 3

2. Don't delay evaluation in patients with severe or persistent bleeding

   • Prompt assessment reduces morbidity and mortality 2

3. Consider that many patients don't regularly inspect their stool

   • Studies show only 27% of people examine both stool and toilet paper every time 5
   • This may lead to delayed presentation and diagnosis

4. Avoid incision and drainage for thrombosed hemorrhoids

   • This is not recommended as a treatment approach 1

5. Don't rely solely on angiography for diagnosis

   • CT angiography has higher diagnostic yield and should be performed first in unstable patients with ongoing bleeding 2

By following this systematic approach to the evaluation of hematochezia, clinicians can efficiently identify the source of bleeding and implement appropriate treatment strategies to improve patient outcomes.