2026 ICD-10-CM Diagnosis Code O10.312Pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester

ICD-10-CM Codes›O00-O9A›O10-O16›O10

ICD-10-CM O10.312
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O10.312 is a billable ICD-10-CM diagnosis code for pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 817 through 819, 831 through 833. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hypertension and hypertensive-related conditions complicating pregnancy; childbirth; and the puerperium and Hypertension with complications and secondary hypertension.

Code Identity

ICD-10-CM Code
O10.312
Billable Status
Yes — Valid for Submission
Code Describes
Pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester
Short Description
Pre-exist hyp heart and chr kidney dis comp preg, second tri
Parent Code
O10.31
Pre-existing hypertensive heart and chronic kidney disease complicating pregnancy

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO10-O16Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium
CategoryO10Pre-existing hypertension complicating pregnancy, childbirth and the puerperium
This CodeO10.312Pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O10.312.

Maternity diagnoses
The Medicare Code Editor detects inconsistencies in maternity cases by checking a patient's age and any diagnosis on the patient's record. The maternity code edits apply to patients age ange is 9–64 years inclusive (e.g., diabetes in pregnancy, antepartum pulmonary complication).

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PRG020
Hypertension and hypertensive-related conditions complicating pregnancy; childbirth; and the puerperium
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR CIR008
Hypertension with complications and secondary hypertension
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Chronic Kidney Disease

You have two kidneys, each about the size of your fist. Their main job is to filter your blood. They remove wastes and extra water, which become urine. They also keep the body's chemicals balanced, help control blood pressure, and make hormones.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert O10.312 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
642.21 Old hyperten NEC-deliver
Approximate The match is approximate rather than exact.
ICD-9-CM
642.23 Old hyperten NEC-antepar
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About O10.312Overview

Is O10.312 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does O10.312 group to?

When pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester is the principal diagnosis on an inpatient stay, it groups to MS-DRG 817, 818, 819, 831, 832, 833, with relative weights from 0.5229 to 1.6880 depending on complications. Higher weights mean higher Medicare reimbursement.

Who can O10.312 be reported for?

The Medicare Code Editor checks pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

What is the ICD-9 equivalent of O10.312?

Under the General Equivalence Mappings, pre-existing hypertensive heart and chronic kidney disease complicating pregnancy, second trimester converts to ICD-9-CM 642.21 (old hyperten NEC-deliver) and 642.23 (old hyperten NEC-antepar). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.