What counts as MAC
Monitored anesthesia care is anesthesia care during a procedure where an anesthesia provider is there to assess and manage the patient, ready to convert to general anesthesia if needed. It's billed with the same anesthesia codes and the same formula as general anesthesia.
The MAC modifiers
- QS: monitored anesthesia care was provided. Informational, used with your staffing modifier.
- G8: MAC for a deep, complex or markedly invasive procedure.
- G9: MAC for a patient with a history of severe heart or lung disease.
A CRNA working without medical direction might bill QZ and QS together. Some payers also use G8 or G9 to decide whether MAC was medically necessary.
Medical necessity
Payers look harder at MAC for short, minor procedures like cataracts, endoscopy and pain injections. Some Medicare contractors have local coverage rules listing which conditions support MAC. Read yours, and make sure the record states the reason in plain words.
MAC isn't moderate sedation
Moderate sedation is usually given by the proceduralist's team and billed with different codes. See MAC vs moderate sedation.
This article is general information, not billing, legal or tax advice. Payer rules change; always check current guidance.