A system for determining a location of an instrument within an anatomy is provided. The system can include a first instrument, which can define at least one lumen. The system can further include a second instrument, which can be received through the at least one lumen. The system can include at least one electrode, which can be coupled to a distal end of the first instrument. The electrode can be responsive to electrical activity to generate at least one signal. The system can include a sensing unit, which can be in contact with the anatomy to sense electrical activity within the anatomy at a location near the instrument. The sensing unit can be in communication with the electrode to receive the signal. The system can further include a control module that can determine, based on the sensed electrical activity and the signal, the location of the first instrument.