What should I do if I notice blood in my stools?

Blood in Stools: Immediate Assessment and Management

If you notice blood in your stools, you need immediate risk stratification based on your hemodynamic status—check your heart rate and blood pressure, and seek urgent medical evaluation within 24 hours for stable bleeding or immediately for unstable bleeding. 1, 2

Immediate Self-Assessment

Calculate your shock index (heart rate divided by systolic blood pressure):

• Shock index >1 = unstable bleeding → Go to emergency department immediately 1, 2
• Shock index <1 = stable bleeding → Urgent outpatient evaluation needed 1, 2

Warning signs requiring immediate emergency care:

• Lightheadedness, dizziness, or fainting 2
• Rapid heart rate or low blood pressure 2
• Large volume of blood or continuous bleeding 1
• Passing blood alone without stool 1

What Your Doctor Will Do

For Stable, Minor Bleeding (Oakland Score ≤8)

You can be discharged for urgent outpatient colonoscopy if you have no other reasons for hospital admission 1. The evaluation pathway includes:

• Digital rectal examination and anoscopy/proctoscopy first to identify common anorectal causes like hemorrhoids 2
• Colonoscopy within 24 hours after bowel preparation as the definitive diagnostic test 2, 3
• Diagnostic yield of colonoscopy ranges from 72-86% for identifying bleeding sources 2, 4

For Major or Unstable Bleeding

Hospital admission is mandatory 1. The management algorithm includes:

• Immediate IV fluid resuscitation and blood transfusion to maintain hemoglobin >7 g/dL 1, 2
  • Higher threshold of 9 g/dL if you have cardiovascular disease 1
• CT angiography performed before endoscopy if you remain unstable after initial resuscitation 1, 2
  • CT angiography detects bleeding at rates as low as 0.3 mL/min 1, 5
• Upper endoscopy may be needed first because 15% of patients with serious rectal bleeding actually have an upper GI source 1

Important Considerations

Cancer Risk

Approximately 6% of patients with rectal bleeding have underlying bowel cancer, making timely colonoscopy critical 2. The estimated colorectal cancer risk ranges from 2.4-11% in patients presenting with rectal bleeding 1.

Age-Related Causes

In elderly patients, angiodysplasia is a common cause, most frequently occurring in the cecum and proximal ascending colon 2, 4.

Medication Review

• Stop NSAIDs immediately as they worsen bleeding, particularly from diverticulosis or angiodysplasia 3
• Do not stop aspirin if you're taking it for cardiovascular disease (secondary prevention)—the timing of resumption depends on bleeding severity and cardiovascular risk 3
• Iron supplements can cause false-positive occult blood tests but do not cause visible blood in stool 6

Critical Pitfalls to Avoid

• Never assume the bleeding is from hemorrhoids without proper evaluation—colonoscopy is essential to exclude cancer and other serious causes 2
• Do not delay seeking care if you have an Oakland score >8—this requires hospital admission 2
• Bright red blood does not always mean a lower GI source—up to 15% have upper GI bleeding 1
• Adequate bowel preparation is essential for accurate colonoscopy—poor preparation leads to missed diagnoses 4

Follow-Up After Initial Evaluation

If colonoscopy is inconclusive but bleeding continues:

• Repeat colonoscopy with better bowel preparation 4
• Consider radionuclide imaging (red blood cell scan) if repeat colonoscopy is negative 4
• CT enterography for suspected small bowel sources 7