Pathology/Lab Coding Alert

Question: A clinician submitted four blood-gas samples taken throughout the day for a single patient for repeat testing. Per the order, we measured pH and pCO2 for each of the four samples, but measured all of the gases with calculated oxygen saturation only on the final specimen. Do we need to use a modifier to bill these tests, and if so, which one?

Florida Subscriber

Answer: For the testing you described, you should bill four unitsof 82803 (Gases, blood, any combination of pH, pCO2, pO2, CO2, HCO3 (including calculated O2 saturation)). Notice that you use one unit of this same code whether you measure just two listed components or the entire list.

Whether to use a modifier will depend on your payer's expectations. Some payers want you to list multiple units of a clinical lab test like 82803 just once, and they want you to place the number of units in the quantity field of the claim form.

Other payers may want you to list the first instance of the test with only the code, but list additional tests on separate claim lines with modifier 91 (Repeat clinical diagnostic laboratory test). Even though you're not performing the exact testing each time, modifier 91 is appropriate because a single code - 82803 - best describes each test encounter.

Notice: A few payers may still request modifier 76 (Repeat procedure or service by same physician or other qualified health care professional) in these cases.

Bottom line: Especially when it comes to modifiers, payers may have different expectations. You can best facilitate claims processing by understanding and complying with those rules.