In simple words: This code describes a follow-up visit for a patient who intentionally poisoned themselves with a pertussis vaccine, or a vaccine containing pertussis.

Poisoning by pertussis vaccine, including combinations with a pertussis component, intentional self-harm, subsequent encounter.

Example 1: A patient is seen in the emergency department after intentionally ingesting a large dose of pertussis vaccine in a suicide attempt. This is the initial encounter and would be coded as T50.A12A. The patient is admitted to the hospital for observation and treatment. Subsequent encounters for this poisoning episode during this admission would be coded as T50.A12D., A patient is treated in the emergency room for intentional pertussis vaccine poisoning. After two weeks, the patient is seen in the clinic for follow-up related to the poisoning incident. This follow-up visit would be coded as T50.A12D., A patient who attempted self-harm by intentionally taking an excessive dose of pertussis vaccine is seen for therapy sessions related to the self-harm behavior and the ongoing effects of the poisoning. These therapy sessions would be coded as T50.A12D.

Documentation should support the diagnosis of intentional self-harm by pertussis vaccine poisoning, including the type of vaccine taken, the amount ingested, and evidence of intent. Subsequent encounter documentation should reflect the ongoing effects and treatment of the poisoning.

** The 7th character 'D' indicates a subsequent encounter. This code should not be used for the initial encounter, which is coded as T50.A12A. If long-term consequences or sequelae develop, use T50.A12S. Do not use this code for accidental poisoning by pertussis vaccine, which is coded elsewhere.