Aceto-electric chromoendoscopy for pre-treatment evaluation of colorectal polyps

[Background and study aim] Using crystal violet (CV) for evaluating colorectal polyps is not recommended anymore due to its potential carcinogenicity. Our aim is to analyze the feasibility of acetic acid together with narrow band imaging (NBI) or blue light imaging (BLI) (aceto-electrical chromoendoscopy; AEC) as a substitute for CV. [Methods] This is a retrospective analysis of patients who underwent AEC for colorectal polyps between April 2020 and March 2021. We used 1.5% acetic acid by spraying through the working channel directly to the lesions. After evaluation, polyps were resected and sent for pathological investigations. [Results] 23 patients constituted the study population (39% female; mean age 69 (range 37-84)). Mean size of the lesions was 15 mm (range 2-90). In all lesions, pit patterns were well visualized with no adverse events encountered. Among 22 adenomatous lesions, the results were, sensitivity of the pit pattern III-IV determined by AEC for pathological adenoma and Tis: 53.0%; specificity: 100%; positive predictive value: 100%; negative predictive value: 38.5%; accuracy: 63.6%. The results for V_H-V_N for SM deep invasive cancer were, sensitivity: 100%; specificity: 77.8%; positive predictive value: 55.6%; negative predictive value: 100%; accuracy: 81.8%. [Conclusion] AEC provides excellent image of colonic mucosa and might have a potential to be an alternative for crystal violet as it is safe, inexpensive, and easy to use.