A neurostimulator is a small implanted device that sends mild electrical impulses to nerves involved in bladder and pelvic function. It may be used for conditions such as overactive bladder, urinary urgency, frequency, or certain types of urinary retention when other treatments have not provided enough relief. The system typically includes a thin lead placed near the sacral nerves and a small pulse generator positioned beneath the skin. The stimulation can be adjusted to find settings that best control symptoms. A revision procedure may reposition or replace a lead, battery, or device if the existing system needs maintenance or is no longer functioning optimally.