A system can include an implantable device, an instrument, a display device and a processor. The implantable device can include a port and a localizer for generating a navigation field. The instrument can include a tracking device for sensing the navigation field. The processor can be operably coupled to the tracking and display devices and operable to determine a real-time location of the instrument relative to the port and a trajectory of the instrument relative to an insertion axis of the port. The processor system can be operable to cause the display device to graphically render the instrument as a plurality of two or three-dimensional rings positioned around an axis coincident with the determined trajectory and in spaced relation to each other along the axis. A first ring of the plurality of rings can be positioned at the determined instrument location relative to a graphical representation of the port location.