Acetic Acid Chromoendoscopy in the Preliminary Diagnosis of Histological Type of Colon Polyp during Colonoscopy

Aim: to increase the efficiency of endoscopic diagnosis of serrated and non-serrated histological types of colon polyps in real time.Materials and methods. From September 2017 to February 2018, 63 polyps were detected among 51 patients (male 11, women 40, aged between 30–78 years, average age 52.2 ± 12.5 years) in all parts of the colon.Polyps were found in all parts of colon, sizes varied: 24 (38.1 %) ≤5 mm, 31 (49.2 %) 6–10 mm, 8 (12.7 %) ≥10 mm. The macroscopic types 0–IIa were 44 (69.8 %), and 0–Is — 19 (30.2 %). During colonoscopy, 1.5%-acetic acid, 5 ml, was sprayed onto the identified polyps. Additionally was blowed 40 ml of air jet. Mucosa was observed endoscopically for 2 minutes. Then polyps were removed and sent for pathology.Results. Use of acetic acid leads to fast acetowhitening reaction of lesions and surrounding mucosa. 2 groups were distinguished (table): 1) Loss of acetowhitening (LAW) of polyps occurs earlier than LAW of surrounding mucosa — «acetowhitening negative». 2) LAW of polyps occurs later than LAW of surrounding mucosa — «acetowhitening positive». Group 1 includes 25 (39.7%) polyps, 88.0% of which were non-serrated: 18(72.0%) — tubular adenoma; 4 (16.0%) — tubular-villous adenoma, one of which had high-grade dysplasia. Only 3(12.0%) polyps were serrated — hyperplastic polyps. Group 2 includes 38 (60.3%) polyps, 97.4% of which were serrated: 24 (63.2%) — hyperplastic polyp; 12 (31.6%) — sessile serrated polyp, including one with low-grade dysplasia, 1 (2.6%) - traditional serrated adenoma. Only 1 (2.6%) polyp was non-serrated — tubular adenoma. This suggests that LAW of non-serrated polyps occurs faster than LAW of surrounding mucosa — «acetowhitening negative». On the contrary, the LAW of serrated polyps is delayed compared to the LAW of the surrounding mucosa «acetowhitening positive». LAW of 4(6.3%) polyps was atypical. The reason for this phenomenon requires further study.Conclusion. Acetic acid chromoendoscopy can be used as a diagnostic method to determine the histological type of polyps during colonoscopy.