Differences in endoscopic views during biopsy through the right and left lower biopsy channels of the upper gastrointestinal endoscope

Background: It has not been established as to which side the biopsy (instrument) channel should be placed in the tip of a front-viewing upper gastrointestinal (GI) endoscope to allow an en-face approach to lesions on various aspects of the stomach wall. Methods: Using a front-viewing two-channel endoscope, we identified a difference in endoscopic views during biopsy between lower-right and lower-left channels. Colored marks were distributed on the lesser curvature (LC), greater curvature (GC), anterior wall (AW), and posterior wall (PW) in the 'stomach' of a dummy for mock-performance of upper GI endoscopy. When biopsy forceps through the different channels touched the marks, an endoscopic photograph was taken. Furthermore, when biopsy specimens were obtained from PW lesions in several patients, endoscopic views were compared between the two biopsy channels. Results: In the dummy study, no remarkable difference was detected in targeting the marks on AW, LC, or GC of the stomach. The dummy and the patient study showed that the lower-right approach could target PW lesions with a more adequate endoscopic view than from the lower left. The lower-left approach targeted PW lesions on the higher body with a nearly blinded endoscopic view. Specimens from PW of the upper body, which could be precisely obtained under direct visual control through the lower-right channel, were no smaller than those obtained using the channel on the lower left. Conclusion: The present study suggests that the lower-right channel may be preferable to the lower-left channel in the tip of a front-viewing upper GI endoscope.