ED Coding and Reimbursement Alert

Question: We had a parent present to the ED with her one-year-old son, and she suspected he had impetigo on his buttocks. The physician determined that it was just diaper rash, but he ordered a KOH test to confirm the presence of candida. Which codes apply to this situation?

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Answer: Diaper rashes are caused either by irritants, such as urine or feces; allergic reactions to diaper materials or baby wipes; or yeast infections, which is the kind of rash you describe.

Diagnosis coding for the condition would certainly include L22 (Diaper dermatitis). And, as B37.2 (Candidiasis of skin and nail) lists L22 as an Excludes2 code, meaning that both conditions can occur at the same time, then you can go ahead and code both together. In terms of sequencing, as the etiology of the diaper rash is known, and as the infectious agent is the subject of the treatment, B37.2 would be the primary diagnosis.

The KOH test is so called because potassium hydroxide, known by its chemical formula KOH, is added to the skin sample to dissolve it and determine if the Candida albicans fungus is present. What is confusing from a coding perspective is that CPT^® lists two KOH tests: 87210 (Smear, primary source with interpretation; wet mount for infectious agents (e.g., saline, India ink, KOH preps)) and 87220 (Tissue examination by KOH slide of samples from skin, hair, or nails for fungi or ectoparasite ova or mites (e.g., scabies)).

As your provider would, presumably, be testing a skin sample in this encounter, both the wording of the descriptor for 87220 and the note accompanying 87210, which states “For KOH examination of skin, hair, or nails, see87220,” would indicate that 87220 would be the correct KOH test to bill. But check with your provider first to see if this was, in fact, the test used in this situation. Of note, these pathology tests are not typically performed/reported by the ED physician but may be part of a more final bill that involves pathology and facility services.