Urology Coding Alert

Question: Most of our patients havePSA testing once per visit. However, sometimes we have patients whose PSA numbers are so high that the machine will not output an accurate count. The lab then must dilute the sample and run the test again to get the correct PSA number. Is this something that should be billed twice as we are running the test twice? I think payment for the repeat test will be denied as the same test on the same date of service; is there an appropriate modifier to use to allow the second PSA to be paid? Or would this be considered an equipment error or malfunction since the original specimen had to be diluted to get the accurate count?

Nebraska Subscriber

Answer: You can bill 84153 (Prostate specific antigen [PSA]; total) once for the original test, but not for the repeat test.

Here's why: At first glance, you could report 84153 a second time and append modifier 91 (Repeat clinical diagnostic laboratory test). However, coding guidelines state that you should not submit modifier 91 for lab tests that are repeated due to malfunctions of the testing equipment or the specimen.