K59.31 Toxic megacolon

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

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.-)

Applies from K59.3 Megacolon, not elsewhere classified

Applicable to

• Dilatation of colon

Excludes1 (never code together)

• congenital megacolon (aganglionic) (Q43.1)
• megacolon (due to) (in) Chagas' disease (B57.32)
• megacolon (due to) (in) Clostridium difficile (A04.7-)
• megacolon (due to) (in) Hirschsprung's disease (Q43.1)

Code first

• , if applicable (T51-T65) to identify toxic agent

Risk adjustment (HCC)

• CMS-HCC V28: HCC 78 — Intestinal Obstruction/Perforation
• CMS-HCC V22: HCC 33 — Intestinal Obstruction/Perforation
• ESRD V24: HCC 33

MS-DRG index

Defines the logic of DRG(s) 393-395 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 556.9 Ulcerative colitis, unspecified (approximate)

Diagnosis Index entries for K59.31

• Dilatation › colon › toxic
• Megacolon (acquired) (functional) (not Hirschsprung's disease) (in) › toxic NEC

Nearby codes

• K59.04 Chronic idiopathic constipation
• K59.09 Other constipation
• K59.1 Functional diarrhea
• K59.2 Neurogenic bowel, not elsewhere classified
• K59.3 Megacolon, not elsewhere classified
• K59.31 Toxic megacolon (this code)
• 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