Shielded trocar with safety locking mechanism

摘要

A trocar is formed from a cannula and an interfitting obturator for penetrating body cavity walls in laparoscopic and endoscopic surgery. The obturator is provided with an improved piercing tip having a pointed blade and an improved locking shield design. The locking mechanism must be actuated before the shield will retract to expose the piercing tip. The shield is located inside the obturator sheath and provides faster coverage of the piercing tip after the body cavity wall has been penetrated. The cannula has an improved thread design to more easily and securely hold the cannula in the incision of the body cavity wall. A one piece inner housing is used in the cannula to reduce the need for welding to prevent gas leakage. The cannula also has improved seals to maintain insufflation of the body cavity and an automatic insufflation valve to facilitate connection to an external gas supply. Reducing fittings may also be used on the cannula to allow the insertion of endoscopic instruments of lesser diameter than the obturator.