L05 vs Q43.6
L05 and Q43.6 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on Q43.6
pilonidal fistula or sinus (L05.-)
L05
Pilonidal cyst and sinus
Not billable
- Chapter 12
- Diseases of the skin and subcutaneous tissue
- Section
- L00-L08
Q43.6
Congenital fistula of rectum and anus
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q38-Q45
Indexed under
- Fistula › anus, anal › congenital (cutaneous)
- Fistula › fecal › congenital (cutaneous)
- Fistula › rectum › congenital (cutaneous)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
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