From the Guidelines
For patients with anemia who cannot tolerate colonoscopy, CT colonography is the best alternative screening and diagnostic test, as recommended by the British Society of Gastroenterology guidelines 1. This non-invasive imaging technique uses computed tomography to create detailed 3D images of the colon and rectum without requiring the insertion of a colonoscope. The procedure still requires bowel preparation similar to conventional colonoscopy, but no sedation is needed, making it safer for patients with anemia or other conditions that increase colonoscopy risks.
Key Considerations
- CT colonography has high sensitivity for detecting polyps and masses larger than 10mm (90% sensitivity), though it is somewhat less effective for smaller lesions 1.
- If suspicious findings are detected, the patient would still need a follow-up procedure for tissue sampling, such as a targeted flexible sigmoidoscopy or a colonoscopy with appropriate precautions.
- For severely anemic patients, iron supplementation and possibly blood transfusion prior to any procedure might be necessary to improve tolerance.
- The radiation exposure from CT colonography is a consideration but is generally outweighed by the benefit of detecting colorectal cancer in high-risk patients who cannot undergo standard colonoscopy 1.
Additional Diagnostic Approaches
- In some cases, video capsule endoscopy may be considered, particularly if there is suspicion of small bowel bleeding 1.
- However, the most recent and highest quality guidelines recommend CT colonography as the first-line alternative to colonoscopy for patients with anemia who cannot tolerate colonoscopy 1.
From the Research
Screening and Diagnostic Tests for Anemia
When a patient with anemia is unable to tolerate colonoscopy, alternative screening and diagnostic tests can be used. The following options are available:
- CT colonography: This is a radiological examination that can be used to diagnose colorectal neoplasia 2. It is recommended as an acceptable and equally sensitive alternative to colonoscopy for patients with alarm symptoms.
- Capsule endoscopy: This can be considered as an alternative to colonoscopy in patients with non-alarm symptoms, although the evidence is low quality 2.
- Fecal occult blood testing: This may be a useful simple screening method in frail patients, as a negative test can avoid the need for invasive tests 3.
Comparison of Screening Tests
Studies have compared the acceptance and preferences of patients between CT colonography and conventional colonoscopy. One study found that patients preferred conventional colonoscopy over CT colonography, despite CT colonography being a safe and noninvasive screening test 4.
- Patient acceptance: CT colonography was found to have higher scores for abdominal pain, abdominal discomfort, and loss of dignity compared to conventional colonoscopy 4.
- Diagnostic accuracy: CT colonography is recommended as an acceptable and equally sensitive alternative to colonoscopy for patients with alarm symptoms 2.
Guidelines and Recommendations
The European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastrointestinal and Abdominal Radiology (ESGAR) have published guidelines on imaging alternatives to colonoscopy 2. The guidelines recommend:
- CT colonography as the radiological examination of choice for the diagnosis of colorectal neoplasia.
- Capsule endoscopy as an alternative to colonoscopy in patients with non-alarm symptoms, although the evidence is low quality.
- Fecal occult blood testing as a useful simple screening method in frail patients.