I10 vs O16
I10 (Essential (primary) hypertension) compared with O16 (Unspecified maternal hypertension), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. I10 carries an Excludes1 note covering O16: “hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| I10Essential (primary) hypertension | O16Unspecified maternal hypertension | |
|---|---|---|
| Billing status | Billable | Non-billable header |
| Classification | I00-I99 — Diseases of the Circulatory System (I00-I99) | O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A) |
| Definition | Essential (primary) hypertension is a billable ICD-10-CM diagnosis code (I10). | Unspecified maternal hypertension is a non-billable ICD-10-CM category code (O16). |
| Includes | high blood pressure hypertension (arterial) (benign) (essential) (malignant) (primary) (systemic) | — |
| Use additional code | code to identify: exposure to environmental tobacco smoke (Z77.22) history of tobacco dependence (Z87.891) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources