reference numerals are used in this description to designate the various components and elements of the instrument of this invention . identical reference numerals designated in the various drawings refer to the identical element or component of the surgical penetration instrument . as used in this description , “ proximal ” or “ proximally ” refers to that portion of the instrument , component , or element which extends toward the user . conversely , “ distal ” or “ distally ” refers to that portion of the instrument , component , or element which extends away from the user . referring to fig1 and 2 , there is shown trocar 2 which incorporates obturator 20 and cannula 8 of the present invention . as illustrated in fig2 obturator 20 is inserted into and through valve 10 and into sleeve housing 14 and sleeve 12 . during insertion , an internal valve ( not shown ) connected to valve lever 18 is opened . seal 10 is preferably a septum valve which surrounds shaft 22 preventing any fluid or gas from escaping through cannula 8 . when shaft 22 is fully inserted into cannula 8 , hub 24 is secured to sleeve housing 14 by handle 26 . penetrating tip 32 of obturator 20 , and a portion of the distal end of shaft 22 , extend distally from sleeve 12 . in an actual surgical procedure utilizing the device of the present invention , a surgeon , using a scalpel , makes a small incision where trocar 2 , shown in fig1 is to be positioned during the surgical procedure . the distal end of trocar 2 is then inserted into the tissue exposed by the small incision . after insertion into the tissue , trocar 2 is oscillated back and forth around its axis to facilitate penetration . separators 34 and 36 on penetrating tip 32 help to separate tissue during oscillation to facilitate the advancement of trocar 2 into the abdominal cavity . after penetration into the abdominal cavity is complete , obturator 20 is removed from cannula 8 by pressing buttons 51 and 52 ( not shown ) which releases handle 26 from sleeve housing 14 . when obturator 20 is removed an internal valve ( not shown ) connected to valve lever 18 closes preventing any fluid or gas from escaping cannula 8 . if desired , a pressurizing gas such as carbon dioxide can be selectively pumped through sleeve 12 via stopcock 16 . surgical instruments , such as linear staplers , graspers , clip appliers , scopes etc . can now be inserted through cannula 8 to perform a procedure at the surgical site . referring again to fig1 and 2 , cannula 8 includes sleeve 12 and sleeve housing 14 . sleeve 12 extends distally from sleeve housing 14 . sleeve housing 14 includes stopcock 16 , valve lever 18 , and seal 10 . obturator 20 , as shown in fig3 has a shaft 22 having a proximal end 42 attached to handle 26 , and a distal end 44 extending therefrom . handle 26 and shaft 22 are formed from single piece of molded polymer . shaft 22 preferably includes a conical penetrating tip 32 which is integrally molded to shaft 22 at its distal end 44 . tip 32 includes first and second separators 34 and 36 which extend outwardly from penetrating tip 32 . handle 26 has a cap 46 attached to the proximal end 42 of shaft 22 . cap 46 is snapped onto handle 26 and is secured thereon by an interference fit . referring now to fig4 and 5 , penetrating tip 32 is molded integrally to shaft 22 at distal end 44 . penetrating tip 32 has circular base 40 and blunt point 38 extending distally from base 40 . base 40 is positioned adjacent to the distal end 44 of shaft 22 . first and second separators 34 and 36 , respectively , have generally straight , linear edge surfaces . each first and second separator 34 and 36 extends longitudinally from adjacent to base 40 toward point 38 of penetrating tip 32 . first and second separators 34 and 36 are spaced about 180 ° from each other , and are positioned proximally to point 38 . referring again to fig3 shaft 22 further includes a reinforcing member 30 disposed thereon . in the embodiment illustrated in fig6 member 30 is a rigid reinforcing hollow tube made of stainless steel , titanium or any other suitable material known to those skilled in the art . using manufacturing methods like injection molding , a polymer such as polycarbonate , or any other suitable polymer known to those skilled in the art , can be injected through member 30 wile forming shaft 22 and handle 26 . other manufacturing methods , readily apparent to those skilled in the art , could also be used to make the present invention . an alternate embodiment of the present invention is shown in fig7 . in this embodiment , shaft 122 , similar to shaft 22 , includes a reinforcing member 130 disposed within the shaft 122 . member 130 is a solid cylindrical rod made of a reinforcing material such as stainless steel , aluminum or any other material known to those skilled in the art . using manufacturing methods like injection molding , shaft 122 and handle 126 ( not shown ) can be integrally molded as a single piece around member 130 . fig8 shows another alternate embodiment , similar to that shown in fig7 wherein shaft 222 includes of a member 230 disposed therein . member 230 is similar to member 130 but has a plus shaped cross - section . as will be appreciated by those skilled in the art , many other suitable cross - sectional configurations other than circular and plus , can be used in the present invention . although particular embodiments of the present invention have been shown and described , other embodiments will become apparent to those skilled in the art without departing form the spirit and scope of the present invention . the terms used in describing the invention are used in their descriptive sense and not as terms of limitations .
in accordance with the present invention there is provided an obturator for penetrating body tissue which contains a handle and a shaft . the shaft has a proximal end attached to the handle and a distal end extending from it . the handle and shaft are formed from a single piece of molded polymer . a substantially rigid reinforcing member which is formed from a material having a greater rigidity than the molded polymer is disposed along the shaft .