Excludes1 pair
Q17- vs Q18.1
Q17 and Q18.1 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on Q17
preauricular sinus (Q18.1)
Q17
Other congenital malformations of ear
Not billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q10-Q18
Q18.1
Preauricular sinus and cyst
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q10-Q18
Use when the record says
- Fistula of auricle, congenital
- Cervicoaural fistula
Indexed under
- Cyst › ear (external)
- Cyst › preauricular
- Fistula › cervical, lateral
- Fistula › cervicoaural
- Fistula › preauricular (congenital)
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027