Q18.0 Sinus, fistula and cyst of branchial cleft

The ICD-10-CM code for Sinus, fistula and cyst of branchial cleft is Q18.0 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

17: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

Section

Q10-Q18: Congenital malformations of eye, ear, face and neck (Q10-Q18)

Category Q18

11 codes (10 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Q18.0:

• Branchiogenic remnant (in neck)
• Infection, infected, infective (opportunistic) › branchial cyst
• Cyst (colloid) (mucous) (simple) (retention) › branchiogenic
• Sinus › branchial cleft (internal) (external)
• Fistula (cutaneous) › branchial (cleft)
• Cyst (colloid) (mucous) (simple) (retention) › cervical lateral
• Fistula (cutaneous) › branchiogenous
• Cyst (colloid) (mucous) (simple) (retention) › branchial (cleft)

Inclusion Terms

• Branchial vestige

U.S. Hospital Utilization

• An estimated 1,265 U.S. inpatient stays in 2023 included Q18.0 among the documented diagnoses.
• 450 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

POA indicator for congenital conditions/anomalies and Q00-Q99 exception

Congenital conditions and anomalies Assign “Y” for congenital conditions and anomalies except for categories Q00- Q99, Congenital anomalies, which are on the exempt list. Congenital conditions are always considered present on admission.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)