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.