ICD-10-CM 2027
ICD-10 code for chin agenesis
From the official ICD-10-CM alphabetic index entry “Agenesis › chin”. Page updated September 29, 2026.
About coding chin agenesis
The ICD-10-CM code for chin agenesis is Q18.8 (Other specified congenital malformations of face and neck).
Within Q18, choose Q18.8 (Other specified congenital malformations of face and neck) only when documentation doesn't support a more specific option: sinus, fistula and cyst of branchial cleft (Q18.0), preauricular sinus and cyst (Q18.1), other branchial cleft malformations (Q18.2), Webbing of neck (Q18.3), Macrostomia (Q18.4), Microstomia (Q18.5), Macrocheilia (Q18.6), Microcheilia (Q18.7) and 1 more.
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 154 (Other Ear, Nose, Mouth and Throat Diagnoses with MCC, relative weight 1.5921), DRG 155 (Other Ear, Nose, Mouth and Throat Diagnoses with CC, relative weight 0.9322) and DRG 156 (Other Ear, Nose, Mouth and Throat Diagnoses without CC/MCC, relative weight 0.6659), in MDC 03 (Diseases and Disorders of the Ear, Nose, Mouth and Throat), 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 chin agenesis ICD-10 codes
What is the ICD-10 code for chin agenesis?
- Q18.8 — Other specified congenital malformations of face and neck.
Is Q18.8 billable?
- Yes. Q18.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q18.8 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q18.8 as a principal diagnosis.
Is Q18.8 a CC or MCC?
- No. Q18.8 is neither a CC nor an MCC under MS-DRG v44.0.