2027 ICD-10-CM Diagnosis Code O91Infections of breast associated with pregnancy, the puerperium and lactation

ICD-10-CM Codes›O00-O9A›O85-O92›O91

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

O91 is a non-billable ICD-10-CM category code for infections of breast associated with pregnancy, the puerperium and lactation, so it cannot be submitted on claims. Use a more specific code from this category instead, such as O91.011, O91.012, O91.013, and O91.019.

Code Identity

ICD-10-CM Code
O91
Billable Status
No — Non-Billable Category
Code Describes
Infections of breast associated with pregnancy, the puerperium and lactation
Short Description
Infect of breast assoc w pregnancy, the puerp and lactation
Chapter
O85-O92
Complications predominantly related to the puerperium

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 CodeO91Infections of breast associated with pregnancy, the puerperium and lactation

Specific Coding for Infect of breast assoc w pregnancy, the puerp and lactationOverview

Non-specific codes like O91 require more characters. Use one of these billable codes instead:

  • O91.0 for Infection of nipple associated with pregnancy, the puerperium and lactation

  • O91.01 for Infection of nipple associated with pregnancy

  • Use O91.02 for Infection of nipple associated with the puerperium

  • Use O91.03 for Infection of nipple associated with lactation

  • O91.1 for Abscess of breast associated with pregnancy, the puerperium and lactation

  • O91.11 for Abscess of breast associated with pregnancy

  • Use O91.12 for Abscess of breast associated with the puerperium

  • Use O91.13 for Abscess of breast associated with lactation

  • O91.2 for Nonpurulent mastitis associated with pregnancy, the puerperium and lactation

  • O91.21 for Nonpurulent mastitis associated with pregnancy

  • Use O91.22 for Nonpurulent mastitis associated with the puerperium

  • Use O91.23 for Nonpurulent mastitis associated with lactation

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to O91: its own notes plus those printed at 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.

On O91 itself
  • 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, its category, or a range that includes it.

Excludes1 2

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

  • Block N60-N65 Disorders of breast
    disorders of breast associated with childbirth (O91-O92)
  • N61 Inflammatory disorders of breast
    inflammatory disorder of breast associated with childbirth (O91.-)

Patient EducationClinical

Breast Diseases

Breast diseases include various conditions and changes in your breast. Most women experience breast changes at some time. Your age, hormone levels, and medicines you take may cause lumps, bumps, and discharges of fluids that are not breast milk.

The full article covers:

  • What are breast diseases?
  • What are the symptoms of breast disease?
  • How are breast diseases diagnosed?
  • What are the treatments for breast disease?

Read the full article at MedlinePlus

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

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 O91Overview

Is O91 a billable code?

No. This is a category header that groups the codes for infections of breast associated with pregnancy, the puerperium and lactation, and headers cannot be submitted on claims. Claims for infections of breast associated with pregnancy, the puerperium and lactation need a more specific code from this category, such as O91.011, O91.012, and O91.013.

Does O91 need an additional code?

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