Underdosing of anticoagulants, subsequent encounter

This code indicates that a patient experienced an adverse effect due to receiving an insufficient dose of an anticoagulant medication, and this is not the initial encounter for this issue. This underdosing could lead to therapeutic failure, such as the formation or recurrence of blood clots, despite the patient being on the medication.

Use this code when documenting a patient presenting for follow-up care related to complications arising from an underdosed anticoagulant, such as a recurrent deep vein thrombosis (DVT) or pulmonary embolism (PE) while on a prescribed anticoagulant. It is also appropriate for ongoing management of a patient whose anticoagulant dose was previously identified as inadequate and is now being adjusted.

• Always assign an additional code for the specific adverse effect or condition resulting from the underdosing (e.g., DVT, PE).
• Ensure the documentation clearly states that the underdosing is the cause of the adverse effect and that this is a subsequent encounter.
• Distinguish from initial encounters for underdosing, which would use the "A" seventh character.