In simple words: This code indicates that a pregnant woman has high blood pressure that existed before the pregnancy and has developed pre-eclampsia, a condition involving high blood pressure and other complications during pregnancy.

Pre-existing hypertension with pre-eclampsia. Includes: conditions in O10 complicated by pre-eclampsia and pre-eclampsia superimposed on pre-existing hypertension. Use additional code from category O10 to identify the type of pre-existing hypertension.

Example 1: A 32-year-old woman with a history of chronic hypertension presents at 28 weeks gestation with elevated blood pressure (160/110 mmHg) and proteinuria.She reports a headache and some blurry vision.She is diagnosed with pre-eclampsia superimposed on chronic hypertension. Code O11 and an additional code from category O10 (e.g., O10.411 for pre-existing essential hypertension) should be used., A pregnant patient at 36 weeks presents for a regular prenatal visit and new onset high blood pressure (150/90), edema and protein in the urine, she also has history of hypertension prior to pregnancy, this should be coded O11., A 28-year-old woman with pre-existing hypertension (managed with medication) becomes pregnant. At 20 weeks of gestation, she develops high blood pressure (150/100 mmHg), generalized edema, and protein in her urine.The physician diagnoses her with superimposed pre-eclampsia. O11 is reported along with an appropriate code from category O10, specifying the type of pre-existing hypertension.

Documentation should include the diagnosis of both the pre-existing hypertension and pre-eclampsia, including the type of pre-existing hypertension. It must also include relevant clinical findings, such as blood pressure readings, presence of proteinuria, and other signs and symptoms. Specific weeks of gestation should be documented whenever known, utilizing the appropriate code from Z3A category.