Unsp pre-existing htn comp pregnancy, third trimester

This code signifies a pregnant patient in her third trimester who has a history of hypertension that existed prior to her current pregnancy, and the specific type or severity of this hypertension is not documented. It indicates that the pre-existing high blood pressure is actively complicating the current pregnancy.

Use this code when the medical record clearly states a diagnosis of pre-existing hypertension in a pregnant patient during her third trimester, but lacks further specificity regarding the type (e.g., essential, secondary) or severity of the hypertension. Documentation should confirm the hypertension predates the pregnancy and is impacting the current gestation.

• Ensure documentation explicitly states "pre-existing" or "chronic" hypertension to differentiate from gestational hypertension.
• If the type of pre-existing hypertension is specified (e.g., essential, secondary), use a more specific O10 subcategory.
• Always sequence this code as a primary diagnosis when it is the main reason for the encounter, or as a secondary diagnosis when it is a co-morbidity complicating the pregnancy.