ICD-10-CM 2027
ICD-10 code for external os frenum
From the official ICD-10-CM alphabetic index entry “Frenum, frenulum › external os”. Page updated September 29, 2026.
About coding external os frenum
The ICD-10-CM code for external os frenum is Q51.828 (Other congenital malformations of cervix).
Within Q51.82, choose Q51.828 (Other congenital malformations of cervix) only when documentation doesn't support a more specific option: cervical duplication (Q51.820) and hypoplasia of cervix (Q51.821).
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.
Common questions about external os frenum ICD-10 codes
What is the ICD-10 code for external os frenum?
- Q51.828 — Other congenital malformations of cervix.
Is Q51.828 billable?
- Yes. Q51.828 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q51.828 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q51.828 as a principal diagnosis.
Is Q51.828 a CC or MCC?
- No. Q51.828 is neither a CC nor an MCC under MS-DRG v44.0.