AbstractBackground and aimsIn our previous study, we visualized and systematically evaluated gas leakage from the forceps plug of the gastrointestinal endoscope system using the Schlieren system. In order to minimize the potential risk of infection from gas leakage from the gastrointestinal endoscope, the development of a new forceps plug was considered urgent. In this study, we analyzed the structure of commercially available forceps plugs and attempted to develop new forceps plugs with improvements.MethodsMicrofocus computed tomography was used to nondestructively analyze the structural changes that occur when forceps are inserted into a commercially available forceps plug. Based on the findings, the basic structure of the newly developed forceps plug was set. We examined the airtightness of these newly developed plugs using the Schlieren system and also compared their fractional resistance with those of commercially available plugs.ResultsAs a result of the nondestructive analysis, all of the commercially available plugs had a single valve, and the cleavage created in the valve during forceps, insertion was large in the case of plugs with slit‐type entrances. In the newly developed forceps plugs, all four types of plugs showed less gas leakage and similar or better usability compared to the commercially available plugs.ConclusionsThe structural weaknesses of the existing gastrointestinal endoscopic forceps plugs were identified. Based on the findings, we froze the design of a prototype of a new forceps plug that was airtight and not inferior in usability compared to commercially available plugs.