Abstract: A trocar for use in surgical procedures including a cannula for maintaining a sealed working channel in a body wall and an obturator which creates the working channel through the body wall while protecting patients and medical personnel from harm is disclosed. A cannula converter which can be employed with the trocar to enable a surgeon to use surgical instruments having a smaller outer diameter than the inner diameter of the cannula without deflating a body cavity is further disclosed. A site stabilizer which can be used with the trocar to prevent the cannula from being inadvertently withdrawn from the body cavity during a surgical procedure is also disclosed.