2026 ICD-10-CM Diagnosis Code O41.1031Infection of amniotic sac and membranes, unspecified, third trimester, fetus 1

ICD-10-CM Codes›O00-O9A›O30-O48›O41

ICD-10-CM O41.1031
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O41.1031 is a billable ICD-10-CM diagnosis code for infection of amniotic sac and membranes, unspecified, third trimester, fetus 1. The 7th character 1 identifies fetus 1 in a multiple gestation pregnancy. 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 Maternal intrauterine infection.

Code Identity

ICD-10-CM Code
O41.1031
Billable Status
Yes — Valid for Submission
Code Describes
Infection of amniotic sac and membranes, unspecified, third trimester, fetus 1
Short Description
Infct of amniotic sac and membrns, unsp, third tri, fetus 1
Parent Code
O41.103
Infection of amniotic sac and membranes, unspecified, third trimester

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO41Other disorders of amniotic fluid and membranes
This CodeO41.1031Infection of amniotic sac and membranes, unspecified, third trimester, fetus 1

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O41.1031.

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 PRG021
Maternal intrauterine infection
Default principal diagnosis: inpatient Yes · outpatient Yes

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 O41.1031 to ICD-9-CMHistory

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

ICD-9-CM
658.41 Amniotic infection-deliv
Approximate The match is approximate rather than exact.
ICD-9-CM
658.43 Amniotic infect-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 O41.1031Overview

Is O41.1031 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report infection of amniotic sac and membranes, unspecified, third trimester, fetus 1 on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character 1 in O41.1031 mean?

The final character 1 identifies the fetus in a multiple gestation pregnancy: this code reports infection of amniotic sac and membranes, unspecified, third trimester for fetus 1.

What MS-DRG does O41.1031 group to?

When infection of amniotic sac and membranes, unspecified, third trimester, fetus 1 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 O41.1031 be reported for?

The Medicare Code Editor checks infection of amniotic sac and membranes, unspecified, third trimester, fetus 1 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 O41.1031?

Under the General Equivalence Mappings, infection of amniotic sac and membranes, unspecified, third trimester, fetus 1 converts to ICD-9-CM 658.41 (amniotic infection-deliv) and 658.43 (amniotic infect-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.