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Ulcerative Colitis ICD-10 Code: K51.90

Last updated: January 4, 2026

Ulcerative colitis is coded using the K51 category in ICD-10-CM. The primary code is K51.90 (Ulcerative colitis, unspecified, without complications).

Quick Reference: Ulcerative Colitis Codes

CodeDescriptionUse When
K51.00Ulcerative pancolitis without complicationsEntire colon involved
K51.10Ulcerative proctitis without complicationsRectum only
K51.20Ulcerative proctosigmoiditisRectum and sigmoid
K51.30Ulcerative rectosigmoiditisRectosigmoid junction
K51.50Left-sided colitisDescending colon to rectum
K51.80Other ulcerative colitisOther specified types
K51.90Unspecified ulcerative colitisType not documented

Complication Codes (5th/6th characters)

Each ulcerative colitis type has complication-specific codes:

5th CharacterMeaning
0Without complications
1With rectal bleeding
2With intestinal obstruction
3With fistula
4With abscess
8With other complication
9With unspecified complications

Example: K51.011 = Ulcerative pancolitis with rectal bleeding

Coding Tips

  1. Document anatomic extent: Pancolitis, left-sided, proctitis
  2. Code complications: Bleeding, fistula, obstruction require specific codes
  3. Sequencing: UC is typically primary; complications secondary
  4. Excludes1: Crohn's disease (K50.-) - never code together
  • K50 - Crohn's disease (different condition)
  • K52.9 - Noninfective gastroenteritis and colitis
  • K51.919 - Ulcerative colitis with unspecified complications

Frequently Asked Questions

What is the ICD-10 code for ulcerative colitis?

K51.90 (Ulcerative colitis, unspecified, without complications) is the primary code. More specific codes like K51.00 (pancolitis) or K51.10 (proctitis) should be used when the anatomic location is documented.

How do I code ulcerative colitis with bleeding?

Add '1' as the 6th character. For example, K51.011 for ulcerative pancolitis with rectal bleeding, or K51.911 for unspecified ulcerative colitis with rectal bleeding.

What's the difference between K51 and K50?

K51 is for ulcerative colitis (confined to colon). K50 is for Crohn's disease (can affect any part of GI tract). These are Excludes1 conditions and cannot be coded together.

Related Resources

Last updated: January 2026. Code data reflects ICD-10-CM 2026 version. This guide is for educational purposes only. Always verify codes against current official guidelines.