Hi.
I certainly don't think that "Drug Screen WNL" is enough documentation to determine a proper code. (May I assume that WNL = within normal limits?).
Before I selected a code, I would want to know the drug(s) or class of drug(s) being tested, the source of the specimen (urine, blood, breath, feces, sputum), the method (e.g., chromtography, assay) and whether it is qualitative or quantitative.
CPT directs you to 80100-80101, 80104, 82486, 99408-99409.
80100: You should see the words "qualitative" and "chromatographic as well as indications of multiple drug classes, i.e., amphetmines, benzodiazepines or alcohols.
80101: You should see only a single drug class and see words like "immuno assay" or "enzyme assay" and NOT see the word "chromatography."
80104: You should see multiple drug classes and anything type of testing OTHER THAN chromatography.
99408 and 99409 are not P&L codes and are in the E/M section under "Counseling Risk Factor Reduction and Behavior Change Inrtervention."
It well may be that your "Drug Screen" was a breathalizer for alcohol and that would put your code in the "Chemistry" section of the CPT.
This sounds like you need to query the provider. Good luck.