How to Read an Itemized Medical Bill

The codes you will see

CPT codes are five-digit codes describing procedures and services. For example, 70450 is a CT scan of the head without contrast. These are the codes most worth checking.

Revenue codes identify the hospital department a charge came from. Less useful for spotting errors, but helpful for understanding where a charge originated.

Visit level codes such as 99281 through 99285 describe how complex an emergency visit was considered to be. Higher level, higher charge.

You do not need to memorize anything

Searching any CPT code along with the word "description" will tell you in seconds what you were billed for. That is usually enough to know whether a line item matches your memory of the visit.

The six patterns worth questioning

Repeats. The same code, same date, same amount appearing more than once.
Services you do not recognize. Medications, supplies, or provider visits you do not remember.
Quantity issues. Being billed for several units of something you received once.
Outliers. A single line dramatically larger than everything else.
Unbundled labs. Many small individual lab charges that are normally billed as one panel.
Timing mismatches. Charges dated before you arrived or after you were discharged.

Compare against your own records

Your discharge paperwork, appointment confirmations, and your insurer's Explanation of Benefits are all useful cross-references. If the bill and the EOB disagree about what was covered, that is worth asking about.