I15 vs O16

I15 (Secondary hypertension) compared with O16 (Unspecified maternal hypertension), from the official CMS tabular data. Both may be reported when both conditions are documented (Excludes2).

Can these codes be reported together?

Yes, when both are documented. I15 carries an Excludes2 note covering O16: “hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

Side by side

	I15Secondary hypertension	O16Unspecified maternal hypertension
Billing status	Non-billable header Report instead: I15.0, I15.1, I15.2, I15.8, I15.9	Non-billable header Report instead: O16.1, O16.2, O16.3, O16.4, O16.5
Classification	I00-I99 — Diseases of the Circulatory System (I00-I99)	O00-O9A — Pregnancy, Childbirth and the Puerperium (O00-O9A)
Definition	Secondary hypertension is a non-billable ICD-10-CM category code (I15).	Unspecified maternal hypertension is a non-billable ICD-10-CM category code (O16).
Use additional code	code to identify: exposure to environmental tobacco smoke (Z77.22) history of tobacco dependence (Z87.891)	—

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources