Obstetric Codes

Report the current trimester of pregnancy, although the condition can occur in more than 1 trimester.

The trimester is described in the final character of the code.

If trimester isn’t part of a code, it’s because the condition always occurs in a specific trimester or the concept of trimester of pregnancy isn’t applicable. Certain ICD-10-CM codes have characters for only certain trimesters because the condition doesn’t occur in all trimesters, but it may occur in more than just 1.

Each category that includes codes for trimester has a code for unspecified trimester. You rarely use the unspecified trimester code. Use it only when the documentation in the record is insufficient to determine the trimester and you can’t get clarification.

This chart gives an example of an obstetric code that identifies trimester.