| 摘要 |
A needle for withdrawing body fluids or injecting liquids comprises a trocar with a sharpened end within a generally conical cannula, with the trocar end extending past the cannula end and with the trocar removable after penetration to leave a tube with increasing i.d. The cannula pref. has external threads on its insertion end so that it can be threaded into body tissue to give min. tearing, and there are mating threaded parts on cannula and trocar so that they can be held together until position and the trocar can then be unscrewed and removed. The trocar may be solid, or may be hollow and have a cap to prevent throughflow of fluid, and a bevelled point.
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