A medical system comprises a probe comprising a coil and a terminal distal end. The medical system further comprises a guide instrument comprising a terminal distal end, a sensor, and a lumen sized to receive the probe. The probe is configured to be inserted through the lumen to reach a worksite. At the worksite, the terminal distal end of the probe is configured to reach at least the terminal distal end of the guide instrument. The medical system further comprises processing hardware configured to receive a first signal from the coil and to receive a second signal from the sensor.
