K31.9 Disease of stomach and duodenum, unspecified

Billable ICD-10-CM code, FY2026.

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) 391-392 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 536.9 Unspecified functional disorder of stomach (approximate)
• 537.9 Unspecified disorder of stomach and duodenum (approximate)

Code annotations containing back-references to K31.9

Back-references to K31

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

Diagnosis Index entries for K31.9

• Disease, diseased › duodenum
• Disease, diseased › stomach
• Disorder (of) › gastric (functional)
• Disturbance (s) › stomach (functional)
• Dysfunction › pylorus
• Gastropathy
• Lesion (s) (nontraumatic) › cardia
• Lesion (s) (nontraumatic) › duodenum
• Lesion (s) (nontraumatic) › gastric
• Lesion (s) (nontraumatic) › gastroduodenal
• Lesion (s) (nontraumatic) › pylorus
• Lesion (s) (nontraumatic) › stomach

Nearby codes

• K31.819 Angiodysplasia of stomach and duodenum without bleeding
• K31.82 Dieulafoy lesion (hemorrhagic) of stomach and duodenum
• K31.83 Achlorhydria
• K31.84 Gastroparesis
• K31.89 Other diseases of stomach and duodenum
• K31.9 Disease of stomach and duodenum, unspecified (this code)
• K31.A Gastric intestinal metaplasia
• K31.A0 Gastric intestinal metaplasia, unspecified
• K31.A1 Gastric intestinal metaplasia without dysplasia
• K31.A11 Gastric intestinal metaplasia without dysplasia, involving the antrum
• K31.A12 Gastric intestinal metaplasia without dysplasia, involving the body (corpus)