Note · Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
Note · Categories B90-B94 are to be used to indicate conditions in categories A00-B89 as the cause of sequelae, which are themselves classified elsewhere. The 'sequelae' include conditions specified as such; they also include residuals of diseases classifiable to the above categories if there is evidence that the disease itself is no longer present. Codes from these categories are not to be used for chronic infections. Code chronic current infections to active infectious disease as appropriate.