When Should Chromoendoscopy Be Used?

IBD dysplasia surveillance is the clearest use case

Chronic colitis increases colorectal neoplasia risk, and dysplasia can be flat or subtle. Modern surveillance emphasizes careful high-definition inspection with targeted biopsy/resection of visible lesions. Dye spraying can enhance topography; virtual chromoendoscopy can improve contrast without the time and mess of dye application.

High definition changed the comparative question

Older trials compared dye-based chromoendoscopy with standard-definition white-light endoscopy, which made the advantage easier to demonstrate. In modern HD practice, the difference between dye and virtual enhancement is smaller. ACG and AGA guidance therefore permit virtual chromoendoscopy as a reasonable alternative in several HD surveillance settings.

Barrett's and gastric mucosa

In Barrett's surveillance, high-definition white light plus virtual chromoendoscopy is commonly used to identify subtle nodularity or abnormal pit/vascular patterns before systematic biopsies. In gastric intestinal metaplasia and early gastric neoplasia, image enhancement can help map subtle areas for targeted biopsy. It does not replace systematic protocols when those are indicated.

Technique and training determine value

Chromoendoscopy is only as good as mucosal cleaning, insufflation, washing, withdrawal time and pattern recognition. Dye should not be sprayed over inadequately prepared mucosa, and virtual enhancement should not be mistaken for automated diagnosis.

When not to use it

Routine dye spraying in every standard colonoscopy has little justification. Use it when the incremental information can change lesion detection, biopsy targeting or resection planning.

A practical clinical approach

1. Define the surveillance or lesion-characterization question.
2. Use high-quality bowel/mucosal preparation first.
3. For IBD surveillance with standard-definition imaging, favor dye-based chromoendoscopy.
4. With high-definition imaging, use dye-based or validated virtual chromoendoscopy according to expertise and lesion risk.
5. Target visible abnormalities for biopsy/resection; do not let enhancement replace systematic sampling when still indicated.

Common errors to avoid

• Using dye to compensate for poor preparation.
• Assuming chromoendoscopy eliminates the need for careful white-light inspection.
• Randomly spraying dye without a defined high-risk indication.
• Calling optical pattern recognition 'histology' without tissue confirmation when pathology is required.

What should trainees remember?

Chromoendoscopy is not a decorative imaging mode. Its value is highest when subtle dysplasia is a realistic threat and the enhanced pattern changes targeting or management.

Free further reading from Dr. Alan B. R. Thomson

See Dr. Thomson's Endoscopy and Diagnostic Imaging and Images in Gastroenterology and Hepatology.

Frequently asked questions

Is dye-based chromoendoscopy mandatory for all IBD surveillance?

No. With high-definition systems, validated virtual chromoendoscopy is an accepted alternative in current guidance.

Does chromoendoscopy replace biopsy?

No. It improves targeting; tissue diagnosis remains important when dysplasia is suspected.

Is chromoendoscopy useful outside the colon?

Yes, particularly for Barrett's esophagus and gastric premalignant/neoplastic assessment.

References

1. Thomson ABR. Endoscopy and Diagnostic Imaging, Parts I-II. CAPstone Academic Publishers; 2012. ISBN 978-1477400579 and 978-1477400654.

2. Thomson ABR. Images in Gastroenterology and Hepatology, Parts 1-2. CAPstone Academic Publishers; 2021. ISBN 979-8719829074 and 979-8743669325.

3. Alkazzi A. IBD Surveillance Colonoscopy: To Spray or Not to Spray! Evidence-Based GI. American College of Gastroenterology; 2025.

4. Rubin DT, et al. ACG Clinical Guideline: Ulcerative Colitis in Adults. Updated June 2025.

5. Shaheen NJ, et al. Updated ACG Guideline: Barrett's Esophagus. Am J Gastroenterol. 2022;117:559-587.