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Topical application of acetic acid (AA) or ethanoic acid 1–3% provides an enhanced view of Barrett’s mucosal surface. The method removes mucus and is followed by a transient whitening due to a transient protein acetylation when exposed to a pH of 2.5–3.0. BE epithelium without neoplasia tends to have longer whitening periods than areas of dysplasia and neoplasia, theoretically due to a reduced cytoplasmic content in worrisome areas. The technique of spraying AA requires practice and patience as detection of the loss of whitening appears as subtle areas of erythema within seconds.

Numerous reports and meta‐analysis have shown the utility in AA chromoendoscopy to identify BE and dysplastic areas. In a remarkable prospective trial of 132 patients conducted by a very experienced group in Portsmouth, UK, acetowhitening improved detection of neoplasia in BE with a cutoff of 142 seconds of application time and revealed neoplastic areas with a sensitivity of 97% and specificity of 84% [4]. In a retrospective report of their experience, Tholoor et al. AA found chromoendoscopy to be superior to standardized random biopsies in detecting dysplasia and neoplasia [5].

Iodine staining with Lugol solution (2.5% iodine) is a useful chromoendoscopy for squamous cell dysplasia and neoplasia. Normal squamous epithelium has a uniform uptake of the dark brown stain due to glycogen within squamous cells compared to dysplastic and neoplasia, where there is a deficiency of glycogen accounting for a void or lack of staining. In addition to a lack of uptake, a pink hue in the unstained mucosa within three minutes seems to be a more specific sign for high‐grade squamous intraepithelial neoplasia or more advanced neoplasia [6]. In a series of 79 patients with 121 lesions, the pink hue as the determinant produced a sensitivity of 91.9% and specificity of 94.0% for high‐grade intraepithelial squamous neoplasia and squamous cell carcinoma.

Indigo carmine and methylene blue have been used as contrast stains and do not have clinical utility in detecting more dysplasia or reducing the number of biopsies during surveillance of BE over electronic chromoendoscopy using narrow‐band imaging (NBI) [7, 8].