2027 ICD-10-CM Diagnosis Code O91.111Abscess of breast associated with pregnancy, first trimester

ICD-10-CM Codes›O00-O9A›O85-O92›O91

ICD-10-CM O91.111
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

O91.111 is a billable ICD-10-CM diagnosis code for abscess of breast associated with pregnancy, first 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 Nonmalignant breast conditions and Other specified complications in pregnancy.

Code Identity

ICD-10-CM Code
O91.111
Billable Status
Yes — Valid for Submission
Code Describes
Abscess of breast associated with pregnancy, first trimester
Short Description
Abscess of breast associated with pregnancy, first trimester
Same as the full description in the CMS dataset.
Parent Code
O91.11
Abscess of breast associated with pregnancy

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO85-O92Complications predominantly related to the puerperium
CategoryO91Infections of breast associated with pregnancy, the puerperium and lactation
This CodeO91.111Abscess of breast associated with pregnancy, first trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O91.111.

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 O91.111: its own notes plus those printed at O91, block O85-O92, and 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 Block O85-O92 Complications predominantly related to the puerperium applies to 114 codes
  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • puerperal osteomalacia (M83.0)
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 O91 Infections of breast associated with pregnancy, the puerperium and lactation applies to 18 codes
  • code to identify infection
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 O91.111, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming O91.111: they are not reported together with it, unless the two conditions are unrelated.

  • N61 Inflammatory disorders of breast
    inflammatory disorder of breast associated with childbirth (O91.-) names O91.-, which includes this code
  • Block N60-N65 Disorders of breast
    disorders of breast associated with childbirth (O91-O92) names O91-O92, which includes this code

Clinical ClassificationClinical

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

CCSR GEN017
Nonmalignant breast conditions
Default principal diagnosis: inpatient No · outpatient No
CCSR PRG028
Other specified complications in pregnancy
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Abscess

An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms.

Read the full article at MedlinePlus

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

Convert O91.111 to ICD-9-CMHistory

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

ICD-9-CM
675.11 Breast abscess-delivered
Approximate The match is approximate rather than exact.
ICD-9-CM
675.13 Breast abscess-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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About O91.111Overview

What is the ICD-10 code for abscess of breast associated with pregnancy, first trimester?

The ICD-10-CM code for abscess of breast associated with pregnancy, first trimester is O91.111 (sometimes written as O91111). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is O91.111 (Abscess of breast associated with pregnancy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report abscess of breast associated with pregnancy, first trimester on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does O91.111 group to?

When abscess of breast associated with pregnancy, first 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 O91.111 be reported for?

The Medicare Code Editor checks abscess of breast associated with pregnancy, first trimester against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

Does O91.111 need an additional code?

When the condition applies, yes. The Use Additional Code note at O91, which applies to O91.111, reads: code to identify infection. The additional code is reported after O91.111.