Manifestation codes should not be used as what type of diagnosis?

Manifestation codes are used to indicate the clinical manifestations or effects of an underlying condition. They serve to clarify the relationship between the underlying condition and its manifestations, but they should not be assigned as the principal diagnosis. The principal diagnosis is defined as the condition that is primarily responsible for the patient’s admission or encounter, and it should represent the main reason for the healthcare service provided.

The use of a manifestation code as the principal diagnosis would not accurately represent the primary condition being treated, potentially leading to incorrect coding and billing practices. Since manifestation codes are specific to the effects of an underlying condition, they do not stand alone and always relate back to an underlying etiology, making them unsuitable for use as a principal diagnosis.

In practice, the principal diagnosis should always be an underlying condition that is directly identified by the clinician, while manifestation codes are appropriately documented as secondary codes in cases where they accompany the primary diagnosis. This ensures that the medical record accurately reflects the patient's condition and the treatment provided.