Which of the following would result in a claim being denied?

• A. An italicized code used as the first listed diagnosis
• B. A correct code used as the first listed diagnosis
• C. A valid procedure code
• D. A claim submitted without patient consent

Answer: (A)

The main concept here is that the first-listed diagnosis must be the principal reason for the encounter and must be a valid, billable code. An italicized code signals that it should not be used as the primary diagnosis for billing purposes—it's a flag that this code isn’t appropriate to describe the main reason for the visit. When a claim lists an italicized code as the first-listed diagnosis, the payer cannot establish a proper principal diagnosis, which often leads to denial because the claim lacks the required justification for the encounter.

Other options describe scenarios that would be acceptable or unrelated to the primary billing rule: using a correct code as the first-listed diagnosis is proper because it accurately reflects the main reason for the visit; a valid procedure code is needed to describe the service performed; and while missing patient consent can cause issues in some contexts, it doesn’t address the requirement for a valid principal diagnosis in the claims workflow. The italicized primary diagnosis is the factor that creates the denial in this context.