FY2027
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Excludes1 pair

A50.2 vs A53.9

A50.2 and A53.9 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 A53.9
syphilis NOS under two years of age (A50.2)
A50.2

Early congenital syphilis, unspecified

BillableUnspecified
Chapter 1
Certain infectious and parasitic diseases
Section
A50-A64
Use when the record says
  • Congenital syphilis NOS less than two years after birth.
Indexed under
  • Syphilis, syphilitic › congenital › early, or less than 2 years after birth NEC
A53.9

Syphilis, unspecified

BillableUnspecified
Chapter 1
Certain infectious and parasitic diseases
Section
A50-A64
Use when the record says
  • Infection due to Treponema pallidum NOS
  • Syphilis (acquired) NOS
Indexed under
  • Syphilis, syphilitic (acquired)
  • Syphilis, syphilitic › conjugal
  • Syphilis, syphilitic › due to blood transfusion
  • Syphilis, syphilitic › general
  • Syphilis, syphilitic › organic

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