If a physician performs a surgical procedure, that procedure comes with a "global period" (0, 10, or 90 days) where all routine postoperative care is bundled into the surgical payment. But what if the patient comes in for something completely unrelated? That is where Modifier 24 comes in.
How to use Modifier 24
Modifier 24 is defined as an "Unrelated evaluation and management service by the same physician or other qualified health care professional during a postoperative period."
It must be appended to the E/M code (e.g., 99213-24), never to a surgical procedure code.
The Crucial ICD-10 Rule (Medical Necessity)
To successfully use Modifier 24, the E/M visit must be for an entirely different diagnosis than the surgery. If the patient had a knee replacement (90-day global) and comes in 30 days later for a severe sore throat and fever, the sore throat ICD-10 proves the visit was unrelated.
NCCI Edits and Global Days
Always verify the exact number of global days assigned to the original procedure before billing. If the global period has expired, Modifier 24 is no longer necessary.