Does the patient need a colonoscopy?

When Does a Patient Need a Colonoscopy?

Colonoscopy is indicated for patients with occult gastrointestinal blood loss, iron deficiency anemia, alarm features (blood in stools, anemia, weight loss), or for age-appropriate colorectal cancer screening, but should not be performed in patients without these indications. 1

Indications for Colonoscopy

Gastrointestinal Bleeding

• Patients with occult GI blood loss and iron deficiency anemia with negative upper endoscopy should undergo colonoscopy to identify intestinal bleeding lesions 1
• Patients presenting with major lower gastrointestinal bleeding should be admitted for colonoscopy on the next available list 1
• Patients with minor self-terminating bleeding (Oakland score ≤8 points) without other indications for hospital admission can be discharged for urgent outpatient colonoscopy 1
• Patients with rectal bleeding who are over 50 years old should undergo colonoscopy within 2 weeks due to 6% risk of underlying bowel cancer 1

Iron Deficiency Anemia

• Iron deficiency anemia is a strong indication for colonoscopy, as colorectal cancer is detected in 7.5% of these patients 2
• The number needed to investigate (NNI) to detect each colorectal cancer in patients with iron deficiency anemia is 13, compared to 53 for upper GI cancers 2
• For non-hospitalized patients with iron deficiency anemia, colonoscopy should be the initial investigation in those over 50 years of age, particularly men, and those with lower values for mean corpuscular volume and hemoglobin 3
• Patients with iron deficiency should undergo endoscopic examination regardless of hemoglobin level 4

Post-Cancer Surveillance

• Patients with a history of colorectal cancer that has been resected with curative intent should have a colonoscopy around the time of initial diagnosis to rule out synchronous neoplasms 1
• If the initial examination is normal, subsequent colonoscopy should be offered after 3 years, and then every 5 years if normal 1

Inflammatory Bowel Disease

• Patients with long-standing, extensive inflammatory bowel disease (ulcerative colitis or Crohn's colitis) should undergo surveillance colonoscopy with systematic biopsies 1
• Surveillance typically begins after 8 years of disease in patients with pancolitis or after 15 years in those with left-sided colitis 1

When Colonoscopy is NOT Indicated

• Colonoscopy should not be performed in patients without alarm features (blood in stools, anemia, weight loss) unless age-appropriate colon cancer screening has not been performed 1
• Patients with constipation without alarm symptoms do not require colonoscopy 1
• Routine small bowel investigation (capsule endoscopy) is not advised in patients with sporadic duodenal adenomas 1

Special Considerations

Obscure Gastrointestinal Bleeding

• Patients with obscure GI bleeding and associated anemia or overt bleeding with melena or maroon blood per rectum should undergo repeat endoscopic examinations 1
• In patients with occult GI blood loss and no anemia, evaluation beyond colonoscopy is not warranted unless upper tract symptoms are present 1

Irritable Bowel Syndrome

• Patients meeting Rome II diagnostic criteria for irritable bowel syndrome without "red flags" (fever, weight loss, blood in stools, anemia, abnormal physical findings) do not routinely require colonoscopy 1
• However, a stool Hemoccult test and complete blood count are recommended for screening purposes in these patients 1

Risk Factors That Increase Need for Colonoscopy

• Age over 50 years 3, 2
• Male gender (7.5 times higher risk for GI malignancies) 3
• Lower mean corpuscular volume 3
• Positive fecal occult blood test 3
• Iron deficiency anemia 5, 6, 4
• Overt rectal bleeding 1

Practical Approach

1. For patients with iron deficiency anemia, perform colonoscopy first, especially in those over 50 years old 2
2. For patients with acute lower GI bleeding, use the Oakland score to determine urgency (score >8 requires hospital admission and urgent colonoscopy) 1
3. For patients with constipation or IBS symptoms without alarm features, colonoscopy is not indicated 1
4. For post-colorectal cancer surveillance, perform colonoscopy at time of diagnosis, then 3 years later, then every 5 years if normal 1

Remember that approximately one-third of patients with a potentially bleeding benign lesion in the upper digestive tract may have another lesion in the colon, so a complete evaluation of both the upper and lower GI tracts is often necessary 5.