Health Information Management

ICD-10 tip: Coding for infectious and parasitic diseases

HIM-HIPAA Insider, March 25, 2013

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The first series of codes in both the ICD-9-CM and ICD-10-CM manuals are infectious and parasitic diseases. What a fun (cough, cough) place to start.

The very first disease listed in the ICD-9-CM Manual is cholera, an infection of the small intestine that causes a large amount of watery diarrhea. That sounds perfectly unpleasant. It’s probably also not a disease you’ll code often unless you start coding for Doctors Without Borders. Cholera occurs in places with poor sanitation, crowding, war, and famine.

Coding for cholera is exactly the same in ICD-9-CM and ICD-10-CM. The only difference is the actual code numbers. If you do get a patient with cholera, you have three choices:

  • Cholera due to Vibrio cholerae 01, biovar cholera
  • Cholera due to Vibrio cholerae 01, biovar eltor
  • Cholera, unspecified

Unfortunately the manuals include plenty of other unpleasant infectious diseases and not all are as easy to translate from ICD-9-CM to ICD-10-CM.

Take tuberculosis (TB) for example. In ICD-9-CM, we use a fifth character to denote how the TB was identified. For example, fifth digit 3 is added when the tubercle bacilli found (in sputum) by microscopy.

ICD-10-CM does not ask for that information.

In addition, while TB is divided by location or affected organ in both ICD-9-CM and ICD-10-CM, the categories are different and they include different subcategories. ICD-9-CM includes one code for TB of the eye—017.3—with six choices for the fifth digit. So you have a total of six possible codes.

ICD-10-CM also includes six codes, but they are very different codes:

  • A18.50, Tuberculosis of eye, unspecified
  • A18.51, Tuberculous episcleritis
  • A18.52, Tuberculous keratitis
  • A18.53, Tuberculous chorioretinitis
  • A18.54, Tuberculous iridocyclitis
  • A18.59, Other tuberculosis of eye

Histoplasmosis is an infection that occurs from breathing in the spores of the fungus Histoplasma capsulatum and is also known as caver’s disease and spelunker’s lung. How often you see this disease in charts will depend on where you (or the organization you code for) are located.

ICD-9-CM includes three codes for histoplasmosis and seven possible fifth digits to identify associated manifestations.

ICD-10-CM includes seven codes:

  • B39.0, acute pulmonary histoplasmosis capsulati
  • B39.1, chronic pulmonary histoplasmosis capsulati
  • B39.2, pulmonary histoplasmosis capsulati, unspecified
  • B39.3, disseminated histoplasmosis capsulati
  • B39.4, histoplasmosis capsulati, unspecified
  • B39.5, histoplasmosis duboisii
  • B39.9, histoplasmosis, unspecified

The ICD-10-CM codes don’t mention any associated manifestations. That’s because ICD-10-CM requires you to use an additional code for any associated manifestations. So instead of adding a fifth character, in ICD-10-CM you’ll add a whole code.

While you’re reviewing the new codes for infectious and parasitic diseases, don’t forget to review the coding guidelines. Many, but not all, of the guidelines remain the same. The guidelines for Methicillin-resistant Staphylococcus aureus look very similar, just with different codes, but the guidelines for sepsis are different.

This article originally appeared on the ICD-10 Trainer blog.

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