FY2027
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Excludes1 pair

K35- vs K37

K35 and K37 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 K37
unspecified appendicitis with peritonitis (K35.2-, K35.3-)
K35

Acute appendicitis

Not billable
Chapter 11
Diseases of the digestive system
Section
K35-K38
K37

Unspecified appendicitis

BillableUnspecified
Chapter 11
Diseases of the digestive system
Section
K35-K38
Indexed under
  • Appendicitis (pneumococcal) (retrocecal)
  • Perityphlitis

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