K59 Other functional intestinal disorders

Category / Non-billable header 17 subcodes

Block: Other diseases of intestines (K55-K64)

Excludes 1 (cannot be coded together)

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

Excludes 2 (not included here)

  • functional disorders of stomach (K31.-)

Subcodes

Subcodes are listed below for reference. Detail pages are not available for chapters 11–22.

Code Description Billable
K59..0 Constipation No
K59..00 Constipation, unspecified Yes
K59..01 Slow transit constipation Yes
K59..02 Outlet dysfunction constipation Yes
K59..03 Drug induced constipation Yes
K59..04 Chronic idiopathic constipation Yes
K59..09 Other constipation Yes
K59..1 Functional diarrhea Yes
K59..2 Neurogenic bowel, not elsewhere classified Yes
K59..3 Megacolon, not elsewhere classified No
K59..31 Toxic megacolon Yes
K59..39 Other megacolon Yes
K59..4 Anal spasm Yes
K59..8 Other specified functional intestinal disorders No
K59..81 Ogilvie syndrome Yes
K59..89 Other specified functional intestinal disorders Yes
K59..9 Functional intestinal disorder, unspecified Yes

Last reviewed: September 2026