2026 ICD-10-CM Diagnosis Code O34.00Maternal care for unspecified congenital malformation of uterus, unspecified trimester

ICD-10-CM Codes›O00-O9A›O30-O48›O34

ICD-10-CM O34.00
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O34.00 is a billable ICD-10-CM diagnosis code for maternal care for unspecified congenital malformation of uterus, unspecified 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). Coders also document this condition as bicornuate uterus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Maternal care for abnormality of pelvic organs.

Code Identity

ICD-10-CM Code
O34.00
Billable Status
Yes — Valid for Submission
Code Describes
Maternal care for unspecified congenital malformation of uterus, unspecified trimester
Short Description
Maternal care for unsp congen malform of uterus, unsp tri
Parent Code
O34.0
Maternal care for congenital malformation of uterus

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO34Maternal care for abnormality of pelvic organs
This CodeO34.00Maternal care for unspecified congenital malformation of uterus, unspecified trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O34.00.

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).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bicornuate uterus
  • Bicornuate uterus affecting pregnancy
  • Bicornuate uterus in pregnancy, childbirth and the puerperium
  • Congenital abnormal shape of fallopian tube
  • Congenital abnormality of uterus in pregnancy, childbirth and the puerperium
  • Congenital abnormality of uterus, affecting pregnancy
  • Congenital anomaly of mother complicating pregnancy
  • Double uterus affecting pregnancy

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Bicornate or bicornis uterus
      • in pregnancy or childbirth
    • Unicornate uterus
      • in pregnancy or childbirth

Clinical ClassificationClinical

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

CCSR PRG017
Maternal care for abnormality of pelvic organs
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Bicornuate Uterus

    a congenital uterine anomaly in which the uterus is divided into two uterine horns with a significant cleft at the uterine fundus due to partial fusion of the mullerian ducts. bicornuate uterus is sometimes associated with a longitudinal vaginal septum and abnormal development of renal tracts.

Patient EducationClinical

Health Problems in Pregnancy

A health problem in pregnancy is any disease or condition that could affect your health or the health of your fetus. Some health problems may make it more likely that you will have a high-risk pregnancy. A high-risk pregnancy is one in which you, your fetus, or both are at higher risk for health problems than in a typical pregnancy.

The full article covers:

  • What are health problems in pregnancy?
  • What raises my risk for health problems during pregnancy?
  • Can chronic health conditions cause problems in pregnancy?
  • Can health problems in pregnancy be prevented?

Read the full article at MedlinePlus

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

Convert O34.00 to ICD-9-CMHistory

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

ICD-9-CM
654.00 Cong abn uter preg-unsp
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 O34.00Overview

Is O34.00 (Maternal care for congenital malformation of uterus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report maternal care for unspecified congenital malformation of uterus, unspecified trimester on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does O34.00 group to?

When maternal care for unspecified congenital malformation of uterus, unspecified 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 O34.00 be reported for?

The Medicare Code Editor checks maternal care for unspecified congenital malformation of uterus, unspecified 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 O34.00?

Under the General Equivalence Mappings, maternal care for unspecified congenital malformation of uterus, unspecified trimester converts to ICD-9-CM 654.00 (cong abn uter preg-unsp). 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.