B27.9
Header — not billableInfectious mononucleosis, unspecified
The ICD-10 code for infectious mononucleosis, unspecified is B27.9.
B27.9 is a non-billable header code. It groups related conditions but cannot be used on its own for reimbursement — select one of the 4 more specific codes below.
Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •This is a non-billable header code. Documentation must support a more specific child code before this diagnosis can be reported on a claim.
- •This code describes an unspecified presentation. If the medical record documents a more specific detail (e.g. laterality, type, or affected site), a more specific sibling code should be used instead — see Related codes below.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Related codes in this category
- B27.0Gammaherpesviral mononucleosisnon-billable header
- B27.1Cytomegaloviral mononucleosisnon-billable header
- B27.8Other infectious mononucleosisnon-billable header
- B27.9Infectious mononucleosis, unspecifiednon-billable header