Pathology/Lab Coding Alert

Question: A clinician submitted a vaginal smear for a patient experiencing discharge due to “cystitis.” We performed an antigen-detection test using amplified nucleic acid probe, and determined the presence of the organism Trichomonas vaginalis. What are the correct procedure and ICD-10 codes?

Missouri Subscriber

Answer: The correct procedure code for the test you describe is 87661 (Infectious agent detection by nucleic acid (DNA or RNA); Trichomonas vaginalis, amplified probe technique).

Avoid using any of the following codes for different tests a lab might perform to identify this organism:

• 87660 (Infectious agent detection by nucleic acid (DNA or RNA); Trichomonas vaginalis, direct probe technique)
• 87808 (Infectious agent antigen detection by immunoassay with direct optical observation; Trichomonas vaginalis)
• 87210 (Smear, primary source with interpretation; wet mount for infectious agents (eg, saline, India ink, KOH preps)).

Regarding the diagnosis code, labs typically use the ordering diagnosis for a test, which in this case, is “cystitis.” Because you don’t have any specific information about the cystitis, including any indication of blood in the urine, the best ICD-10 code based on the clinician’s ordering information is N30.90 (Cystitis, unspecified without hematuria).

Final diagnosis: Upon receiving the lab results identifying the causative organism as Trichomonas vaginalis, the clinician would report the final diagnosis using a code such as A59.03 (Trichomonal cystitis and urethritis).