O91.23 Nonpurulent mastitis associated with lactation

Billable ICD-10-CM code, FY2026.

Applicable to

• Interstitial mastitis associated with lactation
• Lymphangitis of breast associated with lactation
• Mastitis NOS associated with lactation
• Parenchymatous mastitis associated with lactation

Applies from O91 Infections of breast associated with pregnancy, the puerperium and lactation

Use additional code

• code to identify infection

MS-DRG index

Defines the logic of DRG(s) 769 in MDC 14.

Approximate ICD-9-CM (GEMs)

• 675.82 Other specified infections of the breast and nipple associated with childbirth, delivered, with mention of postpartum complication (approximate)
• 675.84 Other specified infections of the breast and nipple associated with childbirth, postpartum condition or complication (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Maternity diagnoses (age 9 through 64): Age conflict edit. These diagnoses are clinically expected only in patients age 9 through 64.

Code annotations containing back-references to O91.23

Back-references to O91.2

• Type 2 Excludes: L03.31 Cellulitis of trunk ("puerperal cellulitis of breast (O91.2)")

Back-references to O91

• Type 1 Excludes: N61 Inflammatory disorders of breast ("inflammatory disorder of breast associated with childbirth (O91.-)")

Diagnosis Index entries for O91.23

• Mastitis (acute) (diffuse) (nonpuerperal) (subacute) › obstetric (interstitial) (nonpurulent) › associated with › lactation
• Puerperal, puerperium (complicated by, complications) › galactophoritis › associated with lactation
• Puerperal, puerperium (complicated by, complications) › lymphangitis › breast › associated with lactation
• Puerperal, puerperium (complicated by, complications) › mammitis › associated with lactation
• Puerperal, puerperium (complicated by, complications) › mastitis › associated with lactation

Nearby codes

• 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 (this code)