Urology Coding Alert

Question: We occasionally have patients whose PSA numbers are so high that they are above what the machine will output as an accurate count. The lab then dilutes the sample and runs the test again to get the correct PSA number. Is this something we can bill twice since we are running the test twice? If so, is there an appropriate modifier to allow the second test to be paid? Or is this considered an equipment malfunction since the original specimen has to be diluted to get an accurate count?

Pennsylvania Subscriber

Answer: No, you should not charge separately for the second test; only report 84154 (Prostate specific antigen (PSA); free) once.

At first glance, it seems that you might be able to report 84154 twice and append modifier 91 (Repeat clinical diagnostic laboratory test) to the second instance. However, when you read the coding guidelines for modifier 91 you’ll see that you should not use modifier 91 “for tests that the provider repeated to confirm initial results because of testing problems with specimens or equipment, or for any reason when a normal one time result is all that is needed.” Because your equipment cannot accurately count these extremely high PSA levels, that could be considered an equipment malfunction and therefore, negates the use of modifier 91.