A trocar (Fr. "three side") is a hollow cylinder with a sharply pointed end, often three-sided, that's used to introduce cannulas and other similar implements into blood vessels or body cavities. Trocars are also used as ports in laparoscopic surgery. The trocar is often passed inside a cannula, and functions as a portal for the subsequent placement of other devices, such as a chest drain, intravenous cannula etc. Surgical trocars are used to perform laparoscopic ('keyhole') surgery. They are us… (More on Trocar)