ICDcodes.org
FY2027

K35 vs K37

K35 and K37 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 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