Toxic reaction to local anesth during preg, unsp trimester

This code signifies an adverse systemic response to a local anesthetic agent administered to a pregnant patient, where the specific trimester of pregnancy is not documented. It covers toxic effects such as central nervous system or cardiovascular manifestations, not allergic reactions.

Apply this code when a pregnant patient experiences a toxic reaction to a local anesthetic, and the medical record does not specify the trimester. Documentation should clearly indicate a toxic (pharmacologic) reaction rather than an allergic or hypersensitivity response.

• Always sequence this code as a secondary diagnosis, following the code for the specific toxic effect (e.g., convulsions, cardiac arrhythmia).
• Distinguish carefully between toxic reactions (pharmacologic overdose) and allergic reactions (immunologic response); allergic reactions are coded differently.
• If the trimester is known, use the more specific O29.3X1, O29.3X2, or O29.3X3 codes.