K59.9 Functional intestinal disorder, unspecified

Billable ICD-10-CM code, FY2026.

Applies from K59 Other functional intestinal disorders

Excludes1 (never code together)

• change in bowel habit NOS (R19.4)
• intestinal malabsorption (K90.-)
• psychogenic intestinal disorders (F45.8)

Excludes2 (not included here)

• functional disorders of stomach (K31.-)

MS-DRG index

Defines the logic of DRG(s) 391-392 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 564.9 Unspecified functional disorder of intestine

Diagnosis Index entries for K59.9

• Complaint › bowel, functional
• Complaint › intestine, functional
• Disease, diseased › bowel › functional
• Disease, diseased › colon › functional
• Disease, diseased › gastrointestinal (tract) › functional
• Disease, diseased › intestine › functional
• Disorder (of) › intestine, intestinal › functional NEC
• Distress › intestinal (functional) NOS
• Dysfunction › colon
• Dysfunction › rectum
• Syndrome › functional › bowel
• Upset › intestinal (large) (small)

Nearby codes

• K59.39 Other megacolon
• K59.4 Anal spasm
• K59.8 Other specified functional intestinal disorders
• K59.81 Ogilvie syndrome
• K59.89 Other specified functional intestinal disorders
• K59.9 Functional intestinal disorder, unspecified (this code)