Neurosurgery Coding Alert

Question: During an office evaluation and management service, the provider performed low-complexity medical decision making (MDM) for an established patient with “toxic myopathy.” Total encounter time was 25 minutes. How should I report this encounter?

Texas Subscriber

Answer: When coding for a patient with toxic myopathy that isn’t specified as drug-induced or alcoholic, you should report G72.2 (Myopathy due to other toxic agents) for the condition along with 99213 (Office or other outpatient visit for the evaluation and management of an established patient, which requires a medically appropriate history and/or examination and low level of medical decision making. When using time for code selection, 20-29 minutes of total time is spent on the date of the encounter.) for the E/M.

Don’t stop there: Per ICD-10 instructions, when you use G72.2, you need to code first for the type of toxic agent. You’ll choose a code from the T51.- (Toxic effect of alcohol) through T65.- (Toxic effect of other and unspecified substances) code set as the primary diagnosis to identify the toxin.

There are a lot of diagnosis codes to choose from within each of these categories, so make sure you have as much information as possible from the encounter form before trying to select a code. For instance, the T53.- (Toxic effect of halogen derivatives of aliphatic and aromatic hydrocarbons) code set breaks out into these codes—and all of them require you to code to the 7th character:

• T53.1- (Toxic effects of chloroform)
• T53.2- (Toxic effects of trichloroethylene)
• T53.3- (Toxic effects of tetrachloroethylene)
• T53.4- (Toxic effects of dichloromethane)
• T53.5- (Toxic effects of chlorofluorocarbons)
• T53.6- (Toxic effects of other halogen derivatives of aliphatic hydrocarbons)
• T53.7- (Toxic effects of other halogen derivatives of aromatic hydrocarbons)
• T53.9- (Toxic effects of unspecified halogen derivatives of aliphatic and aromatic hydrocarbons)

Example: Let’s say that the notes indicate that the patient suffers from toxic myopathy caused by unintentional chloroform poisoning. You’d choose T53.1X1- (Toxic effects of chloroform, accidental (unintentional)) as your primary diagnosis code along with G72.2.