Pathology/Lab Coding Alert

Question: What are the -GY and -GZ modifiers, and how and when should I use them for lab tests? Oregon Subscriber Answer: You should attach modifiers -GYand -GZ to procedure codes that Medicare doesn't cover. Use modifier -GY(Item or service statutorily excluded or does not meet the definition of any Medicare benefit) when Medicare will deny the claim because either Medicare doesn't cover the service or the claim doesn't meet the carrier's requirements for a particular benefit.

For example, a physician orders a lipid panel for an asymptomatic patient who is "curious" about his cholesterol level. Because Medicare statutorily excludes coverage for cholesterol screening, you should code the test as 80061 (Lipid panel) and attach modifier -GY. You do not need an advance beneficiary notice (ABN) for the claim, because Medicare excludes the service from coverage. The -GYmodifier is not mandatory, but Medicare fast-tracks -GYclaims to denial -- and the faster your lab receives the denial, the faster you can bill the patient or secondary insurance for the balance. Use modifier -GZ (Item or service expected to be denied as not reasonable and necessary) when you expect Medicare to deny a service as medically unnecessary and your lab does not have a signed ABN on file.

Example: A female patient reports for an annual pelvic exam and Pap smear. The physician identifies the patient as low-risk for cervical cancer and sends the Pap smear to the lab for evaluation. The physician indicates that 14 months have passed since the patient's last Pap smear, and Medicare will only pay for the procedure once every 24 months for low-risk patients. The lab evaluates the Pap smear and reports the appropriate HCPCS Level II screening Pap code such as G0123 (Screening cytopathology, cervical or vaginal [any reporting system], collected in preservative fluid, automated thin layer preparation, screening by cytotechnologist under physician supervision). You should attach modifier -GZ to show that your lab does not have a signed ABN on file and that you expect Medicare to deny the claim.