O91

Non-Billable

ChapterO00–O9A

Rankcategory

Official Description

Infections of breast associated with pregnancy, the puerperium and lactation

Metadata & Insights

•2026 ICD-10-CM Edition - Effective October 1, 2025.
•Non-billable category (requires more specific sub-code).
•Chapter 15: Pregnancy, Childbirth and the Puerperium (O00-O9A).

CH15 Parent Instructions

Excludes1(Not coded here)

supervision of normal pregnancy (Z34.-)

Excludes2(Not included here)

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

code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.

O85-O92 Parent Instructions

Excludes2(Not included here)

mental and behavioral disorders associated with the puerperium (F53.-)
obstetrical tetanus (A34)
puerperal osteomalacia (M83.0)

Instructional Notes

Use Additional Code

code to identify infection

Clinical Hierarchy

CH15Pregnancy, childbirth and the puerperium (O00-O9A)

O85-O92Complications predominantly related to the puerperium (O85-O92)

O91Infections of breast associated with pregnancy, the puerperium and lactation

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

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

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

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to O91:

blockO85-O92

Complications predominantly related to the puerperium (O85-O92)

View context instructions

chapterCH15

Pregnancy, childbirth and the puerperium (O00-O9A)

View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to O91. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

25 raw paths

Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)2 unique routes

gestational mammary→O91

gestational subareolar→O91

Galactophoritis1 unique routes

gestational, puerperal, postpartum→O91

Gestational3 unique routes

mammary abscess→O91

purulent mastitis→O91

subareolar abscess→O91

Infection, infected, infective (opportunistic)3 unique routes

nipple(3 variants)

associated with(3 variants)

lactation→O91

pregnancy→O91

puerperium→O91

Lymphadenitis1 unique routes

breast

puerperal, postpartum (nonpurulent)→O91

Mammillitis1 unique routes

puerperal, postpartum→O91

Mastitis (acute) (diffuse) (nonpuerperal) (subacute)6 unique routes

obstetric (interstitial) (nonpurulent)(6 variants)

associated with(3 variants)

lactation→O91

pregnancy→O91

puerperium→O91

purulent(3 variants)

associated with(3 variants)

lactation→O91

pregnancy→O91

puerperium→O91

Pregnancy (single) (uterine)2 unique routes

complicated by (care of) (management affected by)(2 variants)

abscess or cellulitis

breast→O91

infection (s)

nipple→O91

Puerperal, puerperium (complicated by, complications)6 unique routes

abscess(6 variants)

areola→O91(2 variants)

associated with lactation→O91

breast→O91(2 variants)

associated with lactation→O91

mammary→O91(2 variants)

associated with lactation→O91

MS-DRG Classification

2026

No direct MS-DRG triggers identified.

Cross Reference

Find Procedures (ICD-10-PCS)

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