N91.4Secondary oligomenorrhea

N91.4 is the ICD-10-CM diagnosis code for secondary oligomenorrhea. It belongs to category N91 (absent, scanty and rare menstruation), block N80-N98 (noninflammatory disorders of female genital tract) and chapter 14 (diseases of the genitourinary system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within N91 (absent, scanty and rare menstruation), N91.4 is specifically for secondary oligomenorrhea. Related codes cover primary amenorrhea (N91.0), secondary amenorrhea (N91.1), amenorrhea, unspecified (N91.2), primary oligomenorrhea (N91.3) and oligomenorrhea, unspecified (N91.5).

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 742 (Uterine and Adnexa Procedures for Non-Malignancy with CC/MCC, relative weight 1.8456), DRG 743 (Uterine and Adnexa Procedures for Non-Malignancy without CC/MCC, relative weight 1.2974), DRG 760 (Menstrual and Other Female Reproductive System Disorders with CC/MCC, relative weight 1.0129) and DRG 761 (Menstrual and Other Female Reproductive System Disorders without CC/MCC, relative weight 0.7041), in MDC 13 (Diseases and Disorders of the Female Reproductive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

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 626.1 (scanty or infrequent menstruation).