The Retroview™ (Pentax Medical, HOYA Co.) colonoscope has a short turning radius at the colonoscope tip, that allows a retroflexed view of the colon during withdrawal. This might allow the detection of polyps hidden behind flexures, folds, and valves, from the cecum to the rectum.
This device offers many advantages, such as the ability to provide a high definition view of the proximal aspects of colonic folds, flexures, and valves with no additional equipment or device costs. The image quality is high definition and the colonoscope also incorporates the I-SCAN technology. The suction/work channel of the colonoscope is available for therapeutic procedures. Polypectomy can be performed with the colonoscope during retroflexion, without losing view of the polyp. The only disadvantages are the higher consumed withdrawal time because the additional retroflexed withdrawal to the standard withdrawal and that a small portion of the colon is obscured by the shaft of the colonoscope in retroflexion that may be the reason why combined standard withdrawal with retroflexed withdrawal has proved to be better than retroflexed withdrawal alone.
The aim of this study is to determinate the polyp and adenoma detection rate via performing a colonoscopy using a conventional scope with standard withdrawal (forward view) and a combined forward and retroflexed withdrawal technique using the RetroView™ colonoscope.
Lesion's dimensions and characteristics will be recorded to determine a difference between both techniques.
MATERIALS AND METHODS Setting: Instituto Ecuatoriano de Enfermedades Digestivas (IECED), Omni Hospital Academic Tertiary Center. We will include patients from January 2019 to November 2019. The study protocol and consent form has been approved by the Institutional Review Board of our institution and will be conducted according to the Declaration of Helsinki. Patients will provide written informed consent.
Intervention: endoscopic technique. Participants will be submitted to two colonoscopies on the same day. First, a standard colonoscopy will be performed using a conventional HD colonoscope with I-Scan (EC 3490LK, PENTAX, Montvale, NJ) that has a 13.2 mm tube diameter and a total length of 2023 mm). Then a second procedure, combining the standard forward view and retroflexed withdrawal will be performed using the Retroview™ colonoscope (EC34-i10TL, Pentax Medical, Montvale, NJ), that has an 11.6 mm tube diameter and 2023 mm length.
The endoscopy images will be seen on a 27-inch, flat panel, HD LCD monitor (Radiance™ ultra-SC-WU27-G1520 model). All participants will have the same colonic preparation with 4 liters of polyethylene glycol (PEG) the day before and bowel preparation will be evaluated using the Boston Bowel Preparation Scale.
Two endoscopists with proficiency in retroflexed withdrawal will perform the colonoscopies. Colonoscopies will be performed in a tandem, random manner. First one endoscopist will perform the conventional colonoscopy using standard withdrawal technique with standard colonoscopes and then the second endoscopist blinded to the first colonoscopy results will perform the second colonoscopy with the Retroview scope and combination withdrawal (retroflexed with standard withdrawal). The operator assigned to each colonoscopy will be chosen randomly. A minimum withdrawal time of 10 minutes will be required for each procedure. After the examination, endoscopist will fill a questionnaire describing each polyp and adenoma found, including the size and location. The withdrawal time spent in each procedure will be measured.
Statistical analysis: Baseline characteristics will be analyzed using Chi-square o Fisher Test for categorical variable and Mann-Whitney Test for continuous variables. If there is more than one polyp in one patient it will be considered individually for statistical purposes. A P value of less than 0.05 will be considered statistically significant. All the statistical analysis will be performed using R.
Limitations: The protocol will be performed in a single-center by six endoscopists. A lack of a control group because the intention is to compare two endoscopic techniques in the same setting.
