K31.1 Adult hypertrophic pyloric stenosis

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Pyloric stenosis NOS

Excludes1 (never code together)

• congenital or infantile pyloric stenosis (Q40.0)

Applies from K31 Other diseases of stomach and duodenum

Includes

• functional disorders of stomach

Excludes2 (not included here)

• diabetic gastroparesis (E08.43, E09.43, E10.43, E11.43, E13.43)
• diverticulum of duodenum (K57.00-K57.13)

MS-DRG index

Defines the logic of DRG(s) 380-382 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 537.0 Acquired hypertrophic pyloric stenosis

Medicare Code Edits (MCE v43.1 (April 2026))

• Adult diagnoses (age 15 through 124): Age conflict edit. These diagnoses are clinically expected only in patients age 15 through 124.

Code annotations containing back-references to K31.1

Back-references to K31

• Type 2 Excludes: K59 Other functional intestinal disorders ("functional disorders of stomach (K31.-)")

Diagnosis Index entries for K31.1

• Constriction › pylorus (adult hypertrophic)
• Hypertrophy, hypertrophic › pylorus (adult) (muscle) (sphincter)
• Obstruction, obstructed, obstructive › gastric outlet
• Obstruction, obstructed, obstructive › pylorus › adult
• Occlusion, occluded › pylorus, adult
• Stenosis, stenotic (cicatricial) › pylorus (hypertrophic) (acquired)
• Stenosis, stenotic (cicatricial) › pylorus (hypertrophic) (acquired) › adult
• Stricture › pylorus (hypertrophic)
• Stricture › pylorus (hypertrophic) › adult

Nearby codes

• K31 Other diseases of stomach and duodenum
• K31.0 Acute dilatation of stomach
• K31.1 Adult hypertrophic pyloric stenosis (this code)
• K31.2 Hourglass stricture and stenosis of stomach
• K31.3 Pylorospasm, not elsewhere classified
• K31.4 Gastric diverticulum
• K31.5 Obstruction of duodenum
• K31.6 Fistula of stomach and duodenum