| 摘要 |
An endoscopic instrument has a portion having an outer surface with a non-circular cross-sectional shape. The non-circular cross-sectional shape may be provided to the instrument by providing peripheral projections or fins along the length of the portion or by providing the periphery of the portion with a polygonal shape. Where fins are used, the fins are preferably quite small and only have a minimal effect on the fluid flow cross sectional area between the interior of the working channel and the endoscopic instrument. The resulting instrument has significantly reduced backlash while maintaining adequate fluid flow in the working channel. According to a second embodiment of the invention, a portion of the interior of the working channel of the endoscope has an interior surface having a non-circular cross sectional shape by the inclusion of a plurality of radially spaced and inwardly directed ribs or by being polygonally shaped. The resulting endoscope reduces the backlash of an endoscopic instrument inserted therein while maintaining adequate fluid flow in the working channel.
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