Q18.4 – Macrostomia

ICD-10-CM 2027 diagnosis code · Congenital malformations of eye, ear, face and neck

Billable code

ICD-10-CM code Q18.4

Code: Q18.4 (claims format: Q184)
Description: Macrostomia
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 17. Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)
Block: Q10-Q18 Congenital malformations of eye, ear, face and neck
Parent codes: Q18

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Q18 – Other congenital malformations of face and neck

Excludes1 (not coded here):

cleft lip and cleft palate (Q35-Q37)
conditions classified to Q67.0-Q67.4
congenital malformations of skull and face bones (Q75.-)
cyclopia (Q87.0)
dentofacial anomalies [including malocclusion] (M26.-)
malformation syndromes affecting facial appearance (Q87.0)
persistent thyroglossal duct (Q89.2)

Block Q10-Q18

Excludes2 (not included here):

cleft lip and cleft palate (Q35-Q37)
congenital malformation of cervical spine (Q05.0, Q05.5, Q67.5, Q76.0-Q76.4)
congenital malformation of larynx (Q31.-)
congenital malformation of lip NEC (Q38.0)
congenital malformation of nose (Q30.-)
congenital malformation of parathyroid gland (Q89.2)
congenital malformation of thyroid gland (Q89.2)

Index terms for Q18.4

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in Q18

Q18.0 – Sinus, fistula and cyst of branchial cleftBillable
Q18.1 – Preauricular sinus and cystBillable
Q18.2 – Other branchial cleft malformationsBillable
Q18.3 – Webbing of neckBillable
Q18.5 – MicrostomiaBillable
Q18.6 – MacrocheiliaBillable
Q18.7 – MicrocheiliaBillable
Q18.8 – Other specified congenital malformations of face and neckBillable
Q18.9 – Congenital malformation of face and neck, unspecifiedBillable

Frequently asked questions

What is ICD-10 code Q18.4?

Q18.4 is the ICD-10-CM code for macrostomia, in the block Q10-Q18 (Congenital malformations of eye, ear, face and neck).

Is Q18.4 a billable code?

Yes. Q18.4 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does Q18.4 belong to?

It belongs to category Q18 – Other congenital malformations of face and neck.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.