In determining when and how to use a code, the primary issues to address are the performance definition, bundling, and last but certainly not least, medical necessity.
Code 51792 is "Stimulus-evoked response (eg, measurement of bulbocavernosus reflex latency time)." Typically, this requires an instrument that allows you to measure in milliseconds the time it takes from stimulation of the tip of the penis to recorded conduction of the nerve impulse to the bulbocavernosus muscle.
Code 51792 does not preclude billing for any of the other urodynamics codes on the same visit, according to the National Correct Coding Initiative.
Ultimately, medical necessity must be met in the eyes of the physician before the service is billed and in the eyes of the payer before it is paid. Unfortunately, physician and payer determinations of medical necessity do not always match.
The following are two separate statements for local coverage determination (LCD) policies by Medicare Administrative Contractors relative to code 51792:
• TrailBlazer Health Enterprises, LLC: "Stimulus-evoked response has a limited application in practical urology but can be used to evaluate cases of suspected cauda equina syndrome."
• Palmetto GBA, LLC: "Stimulus-evoked response: This study measures bulbocavernosus reflex latency time, and may be needed to make a more definitive diagnosis of pelvic floor (sacral reflex arc) denervation. This test is also used for suspected cauda equina syndrome."
Therefore, documentation of the need to study denervation of the pelvic floor would seem to be required to support payment of the code. Additionally, you may run into some payers that will not pay for the service until there is a review of documentation relative to medical necessity, and others that will not pay for this service unless there is an issue related to cauda equina syndrome.
Another aspect of medical necessity that you should consider with respect to all tests but in particular to 51792: "The use of any of these procedures in a screening capacity does not represent a payable service."
The above statement is also pulled from an LCD related to urodynamics coding. However, the statement is not limited to any one LCD but is commonly included in them. Translated, the statement requires that services billed to Medicare, unless otherwise indicated, should be billed because the physician has identified symptoms that need to be further analyzed to make a diagnosis and decide treatment and that the test ordered is based on the presenting symptoms.