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