FY2027
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Excludes1 pair

K31.B vs Q40.0

K31.B and Q40.0 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 K31.B
congenital pyloric stenosis (Q40.0)
K31.B

Hypertrophic pyloric stenosis, in childhood

Billable
Chapter 11
Diseases of the digestive system
Section
K20-K31
Use when the record says
  • Infantile hypertrophic pyloric stenosis
  • Pediatric hypertrophic pyloric stenosis
  • Pediatric pyloric stenosis
Indexed under
  • Stenosis, stenotic › pylorus › in childhood
  • Stenosis, stenotic › pylorus › infantile
  • Stenosis, stenotic › pylorus › pediatric (hypertrophic)
  • Stricture › pylorus › infantile
Q40.0

Congenital hypertrophic pyloric stenosis

Billable
Chapter 17
Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
Section
Q38-Q45
Use when the record says
  • Congenital constriction
  • Congenital hypertrophy
  • Congenital spasm
  • Congenital stenosis
  • Congenital stricture
Indexed under
  • Achalasia › pylorus
  • Pylorospasm NEC › congenital
  • Pylorospasm NEC › newborn
  • Constriction › pylorus › congenital
  • Constriction › pylorus › newborn

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