Ob-Gyn Coding Alert

Reader Questions:

Here’s the Difference Between Wet Mounts and KOH Slides

Question: If our ob-gyn suspects a vaginal infection when a patient presents for her annual gynecological exam and therefore orders a wet mount, how should I code it? If the Pap returns with inflammatory cells and the physician orders another Pap in four months, can I code that as a diagnostic Pap smear?

Texas Subscriber

Answer: For the wet mount, the lab mixes salt solution on a microscope slide with the contents of a vaginal swab and checks for bacteria, yeast cells, trichomonads, white blood cells that indicate infection, or “clue” cells that indicate bacterial vaginosis. The code for this test is 87210 (Smear, primary source with interpretation; wet mount for infectious agents [eg, saline, India ink, KOH preps]). To check specifically for yeast, the lab might perform a KOH slide by mixing the vaginal sample with potassium hydroxide in addition to the salt solution. The KOH destroys bacteria and cells from the vagina, leaving yeast hyphae and spores (if present) that indicate a yeast infection. If the lab performs both a wet mount and a separate KOH slide, you can code two units of 87210.

Keep in mind: For Medicare, use codes Q0111 (Wet mounts, including preparations of vaginal, cervical or skin specimens) or Q0112 (All potassium hydroxide [KOH] preparations) rather than 87210.

Warning: You should never use 87220 (Tissue examination by KOH slide of samples from skin, hair, or nails for fungi or ectoparasite ova or mites [e.g., scabies]) for a vaginal swab sample. Although it is a KOH test for fungus, this code is specifically for skin, hair, or nail specimens.

After clearing up the infection, the physician may order a repeat diagnostic Pap smear (such as 88174 [Cytopathology, cervical or vaginal [any reporting system], collected in preservative fluid, automated thin layer preparation; screening by automated system, under physician supervision]). The physician can order the test based on the findings of inflammatory cells in the original Pap — R87.820 (Cervical low risk human papillomavirus [HPV] DNA test positive) — but the practice will not bill this code for the Pap smear collection.

Other Articles in this issue of

Ob-Gyn Coding Alert

View All