Over months, a stable impedance reading most directly suggests what about the SNM system?

• A. The lead integrity and electrode-tissue interface are stable.
• B. The device's battery is failing.
• C. The IPG has migrated from its original site.
• D. The patient is not using the device.

Answer: (A)

Impedance reflects the resistance to electrical current at the electrode-tissue interface. When impedance stays stable over months, it shows that the electrical path from the lead to the surrounding tissue and the contact between electrode and tissue remain constant. That means the lead is intact and the tissue response around the electrode hasn’t changed, so the system’s conductive pathway hasn’t been disrupted.

If the lead were fractured or had migrated, you’d expect the impedance to drift as the contact conditions change. A failing battery affects power delivery rather than the current path itself, and IPG migration would similarly alter the lead’s position and impedance. So the most direct takeaway from a stable impedance reading is that the lead integrity and electrode-tissue interface are stable.