Infections of breast associated with pregnancy, the puerperium and lactation (O91) ICD-10-CM
The O91 code range covers infections of breast associated with pregnancy, the puerperium and lactation with 25 ICD-10-CM diagnosis codes. 18 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
- code to identify infection
Codes in the O91 Range 25 codes · 18 billable
- O91 Infections of breast associated with pregnancy, the puerperium and lactationNon-billable
- O91.0 Infection of nipple associated with pregnancy, the puerperium and lactationNon-billable
- O91.01 Infection of nipple associated with pregnancyNon-billable
- O91.011 Infection of nipple associated with pregnancy, first trimester
- O91.012 Infection of nipple associated with pregnancy, second trimester
- O91.013 Infection of nipple associated with pregnancy, third trimester
- O91.019 Infection of nipple associated with pregnancy, unspecified trimester
- O91.02 Infection of nipple associated with the puerperium
- O91.03 Infection of nipple associated with lactation
- O91.1 Abscess of breast associated with pregnancy, the puerperium and lactationNon-billable
- O91.11 Abscess of breast associated with pregnancyNon-billable
- O91.111 Abscess of breast associated with pregnancy, first trimester
- O91.112 Abscess of breast associated with pregnancy, second trimester
- O91.113 Abscess of breast associated with pregnancy, third trimester
- O91.119 Abscess of breast associated with pregnancy, unspecified trimester
- O91.12 Abscess of breast associated with the puerperium
- O91.13 Abscess of breast associated with lactation
- O91.2 Nonpurulent mastitis associated with pregnancy, the puerperium and lactationNon-billable
- O91.21 Nonpurulent mastitis associated with pregnancyNon-billable
- O91.211 Nonpurulent mastitis associated with pregnancy, first trimester
- O91.212 Nonpurulent mastitis associated with pregnancy, second trimester
- O91.213 Nonpurulent mastitis associated with pregnancy, third trimester
- O91.219 Nonpurulent mastitis associated with pregnancy, unspecified trimester
- O91.22 Nonpurulent mastitis associated with the puerperium
- O91.23 Nonpurulent mastitis associated with lactation
About the O91 Code Range
These breast and nipple infections are associated with pregnancy, the period after childbirth, or lactation, when the breasts produce milk.
The subdivisions separate nipple infection (O91.0), breast abscess (O91.1), and nonpurulent mastitis (O91.2). Each separates pregnancy from the period after childbirth and lactation. Pregnancy codes then distinguish the first, second, and third trimesters, or an unspecified trimester.
Questions About This Page
How many billable codes are in the O91 range?
Of the 25 codes in this range, 18 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the O91 range classify?
The range classifies infections of breast associated with pregnancy, the puerperium and lactation. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
