A cannula provides access to a surgical site for a camera instrument and one or more minimally invasive surgical instruments. The cannula may include a curved or flexible section when used with flexible surgical instruments. A service port is defined in a sidewall between proximal and distal ends of the cannula, the service port being large enough to allow an object to be transferred between the instruments and a location outside the cannula. An end effector of the surgical instrument may be positioned within the cannula adjacent the service port. The camera instrument may be positioned to place the end effector within a field of view of the camera. An object may be transferred between a service instrument and the surgical instrument within the field of view of the camera.