2027 ICD-10-CM Diagnosis Code Q18.4Macrostomia
ICD-10-CM Codes›Q00-Q99›Q10-Q18›Q18
- Billable — Valid for Submission
- POA Exempt
- Chronic Condition
Q18.4 is a billable ICD-10-CM diagnosis code for macrostomia. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 157 through 159. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Congenital malformations of eye, ear, face, neck.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q18.4 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of eye, ear, face and neck (Q10-Q18).
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Ablepharon
- Ablepharon macrostomia syndrome
- Bilateral congenital macrostomia
- Congenital left sided macrostomia
- Congenital macrostomia
- Congenital right sided macrostomia
- Hypertelorism
- Macrostomia, preauricular tag, external ophthalmoplegia syndrome
- Mandibulofacial dysostosis, macroblepharon, macrostomia syndrome
- Mass of preauricular region
- Sphenoidal dysostosis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q18.4: its own notes plus those printed at Q18, block Q10-Q18, and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- 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)
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q18.4, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming Q18.4: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Macrostomia (congenital) Q18.4
Meloschisis Q18.4
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Macrostomia
greatly exaggerated width of the mouth, resulting from failure of union of the maxillary and mandibular processes, with extension of the oral orifice toward the ear. the defect may be unilateral or bilateral. (dorland, 27th ed)
Patient EducationClinical
Craniofacial Abnormalities
Craniofacial is a medical term that relates to the bones of the skull and face. Craniofacial abnormalities are birth defects of the face or head. Some, like cleft lip and palate, are among the most common of all birth defects. Others are very rare. Most of them affect how a person's face or head looks.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q18.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q18.4Overview
What is the ICD-10 code for macrostomia?
The ICD-10-CM code for macrostomia is Q18.4 (sometimes written as Q184). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q18.4 (Other congenital malformations of face and neck) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report macrostomia on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q18.4 group to?
When macrostomia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 159, 158, 157, with relative weights from 0.6890 to 1.8082 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q18.4 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for macrostomia on inpatient claims. The code appears in the Congenital malformations of eye, ear, face and neck (Q10-Q18) range of the CMS exempt list.
Can Q18.4 be reported with a code from Q75?
Not as a rule. The Excludes1 note at Q18, which applies to Q18.4, lists "congenital malformations of skull and face bones (Q75.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
