Unknown if Extension or Metastasis (code = 9)
There will be cases for which sufficient evidence is not available to adequately assign a stage. Examples include occasions when the patient expires before a workup is completed, when a patient refuses a diagnostic or treatment procedure, or when there is limited workup due to the patient's age or a simultaneous contraindicating condition. If sufficient information does not exist, the case is staged as "unknown" or is considered unstageable.
This code should be assigned very sparingly. If at all possible, contact the responsible physician to see if there is more information about the case which is not in the record, such as diagnostic studies performed prior to admission or documentation in the physician's office records.
Death certificate only cases are staged '9', unknown. Cases of unknown primary site (C80.9) are, by definition, staged as unknown.