CPT Code

CPT stands for Current Procedural Terminology. It's the five-digit code system, maintained by the American Medical Association, that identifies every medical procedure and service billable to insurance. Every line on a medical bill maps to a CPT code, and every negotiated rate in a plan contract is tied to a CPT code.

A few real examples: 99213 is a standard 15-minute office visit with an established patient; 45378 is a diagnostic colonoscopy; 27447 is a total knee replacement; 74177 is a CT scan of the abdomen and pelvis with contrast. Modifiers (two-digit codes appended to the CPT) can change the meaning — modifier 26 means "professional component only," modifier TC means "technical component only," modifier 59 means "distinct procedural service." Coding is where a lot of billing errors happen; upcoding (billing a more complex code than the service warranted) and unbundling (billing separately for components that should be bundled) are the two most common. The CPT system is what makes price transparency possible at all — without a shared code, comparing prices across facilities would be meaningless.

The takeaway: when you get a medical bill, look up the CPT codes on the AMA site or a plan tool. If a code doesn't match what actually happened at the visit, that's a billing error worth disputing in writing.