2026 ICD-10-CM Diagnosis Code O20.0Threatened abortion

ICD-10-CM Codes›O00-O9A›O20-O29›O20

ICD-10-CM O20.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O20.0 is a billable ICD-10-CM diagnosis code for threatened abortion. 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 threatened miscarriage. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Early, first or unspecified trimester hemorrhage.

This medical diagnosis code is frequently used in OB/GYN medical specialties to designate conditions such maternal disorders related to pregnancy.

Code Identity

ICD-10-CM Code
O20.0
Billable Status
Yes — Valid for Submission
Code Describes
Threatened abortion
Short Description
Threatened abortion
Same as the full description in the CMS dataset.
Parent Code
O20
Hemorrhage in early pregnancy

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO20-O29Other maternal disorders predominantly related to pregnancy
CategoryO20Hemorrhage in early pregnancy
This CodeO20.0Threatened abortion

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O20.0.

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.

  • Threatened miscarriage
  • Threatened miscarriage in first trimester
  • Threatened miscarriage in second trimester
  • Threatened miscarriage in third trimester

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Hemorrhage specified as due to threatened abortion

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.

    • Abortion(complete) (spontaneous)
      • spontaneous
        • threatened
    • Abortion(complete) (spontaneous)
      • threatened (spontaneous)
    • Hemorrhage, hemorrhagic(concealed)
      • antepartum (with)
        • before 20 weeks gestation
          • threatened abortion
    • Pregnancy(single) (uterine)
      • complicated by (care of) (management affected by)
        • hemorrhage
          • threatened abortion
    • Pregnancy(single) (uterine)
      • complicated by (care of) (management affected by)
        • threatened
          • abortion
    • Threatened
      • abortion
    • Threatened
      • miscarriage

Clinical ClassificationClinical

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

CCSR PRG009
Early, first or unspecified trimester hemorrhage
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Threatened Abortion

    vaginal bleeding preceding the 20th week of gestation.

Patient EducationClinical

Miscarriage

A miscarriage is an unexpected loss of pregnancy before the 20th week. Most miscarriages happen very early in the pregnancy, often before a woman even knows she is pregnant.

The full article covers:

  • What is a miscarriage?
  • What causes a miscarriage?
  • What are the signs of a miscarriage?
  • How is a miscarriage diagnosed?
  • What is the treatment for a miscarriage?
  • Can a miscarriage be prevented?

Read the full article at MedlinePlus

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

Convert O20.0 to ICD-9-CMHistory

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

ICD-9-CM
640.03 Threaten abort-antepart
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 O20.0Overview

Is O20.0 (Hemorrhage in early pregnancy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report threatened abortion on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does O20.0 group to?

When threatened abortion 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 O20.0 be reported for?

The Medicare Code Editor checks threatened abortion 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 O20.0?

Under the General Equivalence Mappings, threatened abortion converts to ICD-9-CM 640.03 (threaten abort-antepart). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.