Preliminary Diagnosis: Colon Polyps
I. What imaging technique is first-line for this diagnosis?
Fiber-optic colonoscopy is the first-line imaging technique to evaluate colon polyps.
II. Describe the advantages and disadvantages of this technique for diagnosing colon polyps.
Advantages
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Allows for direct visualization, tissue biopsy/polypectomy, and tissue marking for later surgical removal.
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Has the advantage of being radiation-free.
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More sensitive than other imaging modalities to smaller polyps, allowing for earlier diagnosis and treatment.
Disadvantages
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Invasive procedure that requires sedation, which may affect compliance rate.
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May not be able to visualize the proximal colon beyond an obstructing lesion.
III. What are the contraindications for the first-line imaging technique?
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Contraindications include infection, ischemia, or a risk of perforation. Other indications include inability to consent or inability to tolerate a bowel preparation.
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Hemodynamic instability.
IV. What alternative imaging techniques are available?
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Double-contrast barium enema.
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CT colonography.
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MR colonography (if available).
V. Describe the advantages and disadvantages of the alternative techniques for diagnosing colon polyps.
Double-contrast barium enema (DCBE)
Advantages
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Noninvasive.
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Does not require sedation.
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Can visualize the full length of the colon, including beyond a scope-obstructing lesion.
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As sensitive as colonoscopy for larger polyps.
Disadvantages
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Exposes the patient to ionizing radiation.
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There is a requirement for adequate bowel preparation.
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This technique is relatively insensitive for smaller polyps.
CT colonography
Advantages
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Noninvasive.
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Does not require sedation.
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Can visualize the full length of the colon with comparable accuracy to other modalities.
Disadvantages
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Exposure to ionizing radiation.
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Variable experience/availability to this modality.
MR colonography
Advantages
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Does not involve ionizing radiation.
Disadvantages
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Limited availability and experience.
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Can be more prone to artifact.
VI. What are the contraindications for the alternative imaging techniques?
Double-contrast barium enema
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Contraindicated if there is a risk of perforation.
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Contraindicated in pregnant women.
CT colonography
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Contraindicated if there is a risk of perforation.
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Contraindicated in pregnant women.
MR colonography
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Contraindicated in patients who are claustrophobic or who are pregnant.
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