Reply to Triantafyllou

We read with interest the letter from Triantafyllou relating to our report of improved detection of right colon adenomas with additional retroflexion [1].

As Triantafyllou mentioned, it could be assumed that more adenomas are detected after three or more forward-view examinations [2]. However, we do not think that significant differences will be observed. Our study [1] indicated that retroflexion leads to additional detection of adenomas, which are usually missed on repeated forward-view examinations. However, this depends on the adenoma detection rate of each physician.

A previous study [3] showed an adenoma miss rate of 9.8 %, which was comparable to the 10.4 % miss rate in our study.

Although the frequency of surveillance colonoscopy in our study was relatively higher (27.1 %) than that in a previous study [4], and 8 of the 11 physicians were inexperienced, improved adenoma detection with retroflexion reflected the situation in real clinical practice.

The letter mentions that each endoscopist might have subconsciously introduced a bias to demonstrate the benefit of retroflexion. We do not agree with this. To minimize adenoma yields during retroflexion, each forward-view examination was performed for at least 2 minutes and more carefully than the routine examinations we perform. Moreover, we could not predict, at the time of study design [5], whether retroflexion would show this benefit. Although we aimed to evaluate improved detection of sessile serrated adenomas/polyps in old female patients, the results did not show this. Similarly to a previous study [4], we also planned to show that retroflexion showed no effects when the results had no significant benefit, because the result of absence of effects has its own value in this controversial issue regarding right colon retroflexion. We tried to overcome and minimize this bias subconsciously and consciously, and did not attempt to demonstrate the benefits of retroflexion.

• References

• 1 Lee HS, Jeon SW, Park HY. et al. Improved detection of right colon adenomas with additional retroflexion following two forward-view examinations: a prospective study. Endoscopy 2017; 49: 334-341
• 2 Guo CG, Zhang F, Ji R. et al. Efficacy of segmental re-examination of proximal colon for adenoma detection during colonoscopy: a randomized controlled trial. Endoscopy 2017; 49: 243-250
• 3 Hewett DG, Rex DK. Miss rate of right-sided colon examination during colonoscopy defined by retroflexion: an observational study. Gastrointest Endosc 2011; 74: 246-252
• 4 Triantafyllou K, Tziatzios G, Sioulas AD. et al. Diagnostic yield of scope retroflexion in the right colon: a prospective cohort study. Dig Liver Dis 2016; 48: 176-181
• 5 Lee HS, Jeon SW. Is retroflexion helpful in detecting adenomas in the right colon?: a single center interim analysis. Intest Res 2015; 13: 326-331