| 摘要 |
A medical needle 1 including a tubular stylet 30 has one or more apertures 32, 32A-F at its distal end 16, which are located and dimensioned to prevent occlusion by body tissue. The aperture may be formed by a convexly sided, transverse channel 32B cut into the needle wall 19 or can face rearwardly. Alternatively, a plurality of spaced, longitudinal slits 32C or circular apertures 32D can be provided by laser perforation. The needle can be associated with an outer cutting sheath 34 housing a trocar 21 for use in ultrasound imaging. In further embodiments, the needle can constitute the stylet of an aspiration biopsy needle (FIG. 8) or a needle assembly can comprise a stylet 130 within a cannula 140, the stylet having an expanded distal tip 133 of cross-section complimentary to that of the cannula bore so as to prevent occlusion of the cannula end by tissue (FIG. 7).
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