| 摘要 |
A trocar (10) for placement in the lumen (24) of a cannula to facilitate insertion of the cannula (20) through the wall of a body cavity is described. The trocar (10) comprises a handle (28), an obturator (30) having a proximal portion (31) and a distal portion with a cutting surface (35) for piercing the wall of the body cavity, and an axis (A). The proximal and distal portions of the obturator (30) are mounted for relative rotational movement about the axis (A) of the obturator (30). A mechanism retracts the obturator (30) proximally relative to the cannula (20) along an axial path as the proximal (31) and distal portions rotate relative to each other after the cutting surface (35) has at least partially penetrated through the wall of the body cavity. Preferably, the path is free of distal movement of the obturator (30) relative to the cannula (20). |
