O16.1 ICD-10-CM Code: Unspecified maternal hypertension, first trimester
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FY 2026 Apr update / Pregnancy, childbirth and the puerperium (O00-O9A) / Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium (O10-O16)
O16.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceUnspecified maternal hypertension, first trimester
High blood pressure in a pregnant woman during the first three months of pregnancy, without a specific underlying cause identified.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for O16.1 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for O16.1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for O16.1 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for O16.1 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for O16.1 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for O16.1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for O16.1 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is O16.1 an HCC code?
No. O16.1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
O16.1 is the ICD-10-CM diagnosis code for unspecified maternal hypertension, first trimester. High blood pressure in a pregnant woman during the first three months of pregnancy, without a specific underlying cause identified. O16.1 sits in the ICD-10-CM chapter for pregnancy, childbirth and the puerperium (o00-o9a), within the section covering edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium (o10-o16).
O16.1 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This code is for unspecified hypertension; if a specific type (gestational, chronic, etc.) is documented, use a more specific code.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for O16.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is for unspecified hypertension; if a specific type (gestational, chronic, etc.) is documented, use a more specific code
- •First trimester is defined as weeks 1-13 of pregnancy