trocar

thumb|Disposable trocars thumb|Laparoscopic instruments for insertion through trocars

A trocar (or trochar) is a medical or veterinary device traditionally used in draining or venting procedures, now also (informally termed a port) prominent in minimally invasive surgery. Trocars are typically made up of an obturator (which may be metal or plastic, and with a pointed or tapered tip), within a cannula (essentially a rigid tube), and often with a seal. They allow passive evacuation of excess gas or fluid from organs within the body; some also include a valve mechanism to allow for insufflation. Trocars designed for placement through the chest and abdominal walls during thoracoscopic and laparoscopic surgery function as portals for the subsequent insertion of other endoscopic instruments, such as grasper, scissors, stapler, electrocautery, suction tip, etc.