Randomized Clinical Trial
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 28, 2020; 26(16): 1962-1970
Published online Apr 28, 2020. doi: 10.3748/wjg.v26.i16.1962
Retrograde inspection vs standard forward view for the detection of colorectal adenomas during colonoscopy: A back-to-back randomized clinical trial
Timo Rath, Lukas Pfeifer, Clemens Neufert, Andreas Kremer, Moritz Leppkes, Arthur Hoffman, Markus F Neurath, Steffen Zopf
Timo Rath, Lukas Pfeifer, Clemens Neufert, Andreas Kremer, Moritz Leppkes, Markus F Neurath, Department of Internal Medicine 1, Division of Gastroenterology, Ludwig Demling Endoscopy Center of Excellence, Friedrich-Alexander-University, Erlangen Nuernberg, Erlangen 91054, Germany
Arthur Hoffman, Department of Internal Medicine, Division of Gastroenterology, Klinikum Aschaffenburg, Aschaffenburg 63739, Germany
Steffen Zopf, Department of Internal Medicine, Division of Gastroenterology, Klinikum Fürth, Fürth 90766, Germany
Author contributions: Rath T, Zopf S and Neurath MF were responsible for the study conception and design, data analysis; Hoffman A was involved in data interpretation and manuscript drafting; Rath T, Pfeifer L, Leppkes M, Neufert C, Zopf A, and Kremer A were involved in patient recruitment and performing of the colonoscopies; all authors reviewed and approved the final version to be published.
Institutional review board statement: The study was reviewed and approved by the Institutional Review Board of the Friedrich-Alexander University Erlangen.
Clinical trial registration statement: The study was registered at ClinicalTrials.gov under the following ID: NCT04107376.
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: All authors declare no potential conflicting interests related to this paper.
Data sharing statement: No additional data are available.
CONSORT 2010 statement: The authors have read the CONSORT 2010 Statement, and the manuscript was prepared and revised according to the CONSORT 2010 Statement.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Timo Rath, MD, PhD, Full Professor, Department of Internal Medicine 1, Division of Gastroenterology, Ludwig Demling Endoscopy Center of Excellence, Friedrich-Alexander-University, Erlangen Nuernberg, Ulmenweg 18, Erlangen 91054, Germany. timo.rath@uk-erlangen.de
Received: February 3, 2020
Peer-review started: February 3, 2020
First decision: February 27, 2020
Revised: March 26, 2020
Accepted: April 17, 2020
Article in press: April 17, 2020
Published online: April 28, 2020
ARTICLE HIGHLIGHTS
Research background

Due to its inverse association with the incidence of interval colorectal cancer (CRC), the adenoma detection rate (ADR) serves as a key benchmark criterion for quality assessment in screening and surveillance colonoscopy worldwide. In this regard it has been shown that a 1% increase of the ADR results in a decrease of interval CRC incidence by 3%. At the same time, colonic neoplasia can frequently be missed during screening colonoscopy with miss rates for adenomas reaching up to 26% and human error as well as blind spots are considered the major factors contributing to these high miss rates.

Research motivation

Among the various means to limit miss rates, simple modification of standard colonoscopy such as change of patients’ position, appliance of abdominal compression or a second inspection of the colon in either standard forward view (SFV) or retroflected view (RFV) have shown to improve ADR. The latter has been addressed by several studies and although it has been shown that a second inspection in SFV or RFV can significantly increase ADR, these studies have utilized second inspection predominantly in the right sided colon. Within this study we therefore analyzed whether additional inspection of the whole colon in RFV can increase ADR compared to an additional inspection in SFV.

Research objectives

In this study we aim to assess whether inspection of the whole colon in RFV compared to standard forward view SFV can increase ADR.

Research methods

To address the question whether additional retrograde inspection of the whole colon can significantly increase ADR, we designed this study as prospective randomized back-to-back trial, in which patients were randomized used sealed envelopes into the following arms: (1) RFV arm: Colonoscopy was initially performed with SFV, followed by a second inspection of the whole colon in RFV; and (2) SFV arm: Colonoscopy was initially performed with SFV, followed by a second inspection of the whole colon again with SFV. Insertion time as well as withdrawal times in every segment under either SFV or RFV were recorded using a stop watch and all polyps and adenomas found were removed using either cold- or hot-snare polypectomy.

Research results

205 patients were randomly assigned to the RFV (n = 101) and SFV (n = 104) arm. In the RFV arm, both polyp detection rate (PDR) and ADR were increased under second inspection in RFV. Likewise, in the SFV arm, PDR and ADR also increased under second inspection and importantly, no significant differences in ADR and PDR between the SFV and RFV arm were found. Consistent with this, the mean number of adenomas per patient (APP) was increased in both, the RFV and SFV (APP RFV arm: 1st SFV: 1.71; 2nd RFV: 2.38; APP SFV arm: 1st SFV: 1.83, 2nd SFV: 2.2). The majority of adenomas additionally found during second inspection in RFV or in SFV were located in the transverse and left-sided colon and were > 5 mm in size.

Research conclusions

Second inspection of the whole colon in either standard forward view or retroflected view leads to increased adenoma detection with no significant differences between these two inspections modalities. Hence, increased detection is most likely a feature of the second inspection itself but not of the inspection mode.

Research perspectives

A second inspection of the colon in either standard forward view or retroflected view can be considered as an easy approach to increase ADR. Further large multi-center studies should assess whether this approach can increase effectiveness of screening or surveillance colonoscopy and reduce CRC mortality.