Pathology/Lab Coding Alert

Question: What are the restrictions on using modifier 90 for billing referred lab tests?


Texas Subscriber
Answer: You should use modifier 90 (Reference [outside] laboratory) if you are an independent lab billing for a test that you did not perform in-house.

Modifier 90 indicates to your payer that a party other than you, the reporting lab, performed a particular procedure. Medicare says that it will only process claims for referred laboratory services for labs having specialty code 69--that is, independent clinical laboratories. Also note that CPT does not list 90 as one of the modifiers approved for hospital outpatient use.

When you report referred tests with modifier 90, you must include the name, address and CLIA number of both the referring and reference laboratories on your Medicare claims. Medicare will pay the claim that you report with modifier 90 at the rate used for the reference lab's jurisdiction. If you file paper claims on form CMS 1500, you cannot use the same form for both referred and self-performed laboratory services. Rather, you'll have to file two separate claims.
 
You can read about Medicare's rules for referred laboratory services in Chapter 16 Section 40.1 of the Medicare Claims Processing Manual available online at http://www.cms.hhs.gov/manuals/pm_trans/R23CP2.pdf. The rules specified in this section do not apply to services performed in a physician-office laboratory or a qualified hospital laboratory.

Reader Questions and You Be the Coder were prepared with the assistance of R. M. Stainton Jr., MD, president of Doctors' Anatomic Pathology Services in Jonesboro, Ark.