O91.03Infection of nipple associated with lactation

O91.03 is the ICD-10-CM diagnosis code for infection of nipple associated with lactation. It belongs to category O91 (infections of breast associated with pregnancy, the puerperium and lactation), block O85-O92 (complications predominantly related to the puerperium) and chapter 15 (pregnancy, childbirth and the puerperium). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within O91.0 (infection of nipple associated with pregnancy, the puerperium and lactation), O91.03 is specifically for infection of nipple associated with lactation. Related codes cover pregnancy (O91.01) and the puerperium (O91.02).

Use an additional code to identify infection.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 769 (Postpartum and Post Abortion Diagnoses with O.R. Procedures, relative weight 1.6673) and DRG 776 (Postpartum and Post Abortion Diagnoses without O.R. Procedures, relative weight 0.6721), in MDC 14 (Pregnancy, Childbirth and the Puerperium), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

The Medicare Code Editor treats this as a maternity diagnosis, expected only for patients age 9 through 64.

It is on the CMS list of diagnoses consistent only with female patients (the sex-conflict edit itself was retired in FY2025).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 675.04 (infections of nipple associated with childbirth, postpartum condition or complication).