Every year, influenza season is considered to stretch from October through May. The peak occurs between December through February, causing a lot of hospital encounters— whether as inpatients, emergency department visits, or physician office visits.
Within the medical world, there are different types of influenza viruses. In order to reflect the type of influenza appropriately, the coding professional must carefully examine the documentation provided by the physician in order to assign the correct influenza code. Within this article, we will discuss the different types of influenza and the documentation/coding nuances for each.
Sometimes the type of influenza will not be identified, but the physician will still document “influenza” and treat it as such. Within the alphabetical index, this would be considered an unidentified influenza virus (J11.x). Other times, the physician will order a nasal swab and it will come back positive for Influenza A or Influenza B. In these cases, the influenza would be indexed as Influenza, identified influenza virus, NEC (J10.x).
Novel A Influenza virus is considered to be an influenza arising from animal origin, and is actually somewhat rare. Some of the key words the physician must document in order to assign a code for Novel A are: “novel”, “avian”, “swine”, “H1N1”, “H5N1”. The inclusive list of sub terms can be found within the alphabetical index and are also listed in the tabular index under J09. X. These codes can only be assigned on confirmed cases of Novel Influenza because these are nationally reported infectious diseases. If the physician uses equivocal terms such as “possible” or “probable” a code from the J09 section should not be assigned and the physician should be queried for clarification.
There are times when the coder will see documentation of “influenza like illness”. In the alphabetical index, there is a specific entry for this, which directs the coder back to the main term of influenza. Because there is a specific alphabetical index entry, this diagnosis is appropriate for assignment on both inpatient and outpatient cases.
Under all specified influenza types, there is a subset of manifestations defined by the word “with”. Referring back to the Official Coding Guidelines for ICD-10-CM and PCS, the diagnoses listed under the term “with” are assumed to be linked and can be coded as such (i.e., influenza with pneumonia).
It’s important to remember chart documentation is critical when assigning the appropriate code for influenza. The coder should carefully review the alphabetical index entries and assign the most appropriate code. Remember that Novel A Influenza and Influenza A are not the same. Influenza A is most common, whereas Novel A Influenza is rather rare.
Director of Client Services, Excite Health Partners