2027 ICD-10-CM Diagnosis Code O12.03Gestational edema, third trimester

ICD-10-CM Codes›O00-O9A›O10-O16›O12

ICD-10-CM O12.03
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

O12.03 is a billable ICD-10-CM diagnosis code for gestational edema, third trimester. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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 Other specified complications in pregnancy.

Code Identity

ICD-10-CM Code
O12.03
Billable Status
Yes — Valid for Submission
Code Describes
Gestational edema, third trimester
Short Description
Gestational edema, third trimester
Same as the full description in the CMS dataset.
Parent Code
O12.0
Gestational edema

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO10-O16Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium
CategoryO12Gestational [pregnancy-induced] edema and proteinuria without hypertension
This CodeO12.03Gestational edema, third trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O12.03.

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).

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to O12.03: its own notes plus those printed at Chapter 15. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • supervision of normal pregnancy (Z34.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • postpartum necrosis of pituitary gland (E23.0)
  • puerperal osteomalacia (M83.0)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.

Notes

General instructions on how these codes are used.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
  • Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
  • Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
  • 1st trimester- less than 14 weeks 0 days
  • 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
  • 3rd trimester- 28 weeks 0 days until delivery

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name O12.03, its category, or a range that includes it.

Includes 1

These notes mention O12.03.

  • O15 Eclampsia
    convulsions following conditions in O10-O14 and O16 names O10-O14, which includes this code

Excludes1 1

These codes carry an Excludes1 note naming O12.03: they are not reported together with it, unless the two conditions are unrelated.

  • R60 Edema, not elsewhere classified
    gestational edema (O12.0-) names O12.0-, which includes this code

Excludes2 2

These codes carry an Excludes2 note naming O12.03: its condition is not part of those codes, and both may be reported when the patient has both.

  • O26.0 Excessive weight gain in pregnancy
    gestational edema (O12.0, O12.2) names O12.0, which includes this code
  • O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium
    hypertensive disorders (O10-O16) names O10-O16, which includes this code

Clinical ClassificationClinical

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

CCSR PRG028
Other specified complications in pregnancy
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Edema

Edema means swelling caused by fluid in your body's tissues. It usually occurs in the feet, ankles and legs, but it can involve your entire body.

Read the full article at MedlinePlus

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

Convert O12.03 to ICD-9-CMHistory

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

ICD-9-CM
646.11 Edema in preg-delivered
Approximate The match is approximate rather than exact.
ICD-9-CM
646.12 Edema in preg-del w p/p
Approximate The match is approximate rather than exact.
ICD-9-CM
646.13 Edema in preg-antepartum
Approximate The match is approximate rather than exact.
ICD-9-CM
646.14 Edema in preg-postpartum
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About O12.03Overview

What is the ICD-10 code for gestational edema, third trimester?

The ICD-10-CM code for gestational edema, third trimester is O12.03 (sometimes written as O1203). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is O12.03 (Gestational edema) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report gestational edema, third trimester on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does O12.03 group to?

When gestational edema, third trimester is the principal diagnosis on an inpatient stay, it groups to MS-DRG 833, 832, 831, 819, 818, 817, with relative weights from 0.5000 to 1.7586 depending on complications. Higher weights mean higher Medicare reimbursement.

Who can O12.03 be reported for?

The Medicare Code Editor checks gestational edema, third 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 O12.03?

Under the General Equivalence Mappings, gestational edema, third trimester converts to ICD-9-CM 646.11 (edema in preg-delivered), 646.12 (edema in preg-del w p/p), and 646.13 (edema in preg-antepartum). The mapping is approximate, so confirm the match fits the documentation.