Alphabetic Index FY2027

K52.1

Toxic gastroenteritis and colitis

FY2027Chapter 11: Diseases of the digestive system/K50–K52 Noninfective enteritis and colitis

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Gastrointestinal tract and Genitourinary systemHospital CC

K52.1 (also written K521) is a billable ICD-10-CM diagnosis code for toxic gastroenteritis and colitis. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 14 codes in category K52 (Other and unspecified noninfective gastroenteritis and colitis). The Alphabetic Index lists it under 18 entries. Its coding notes include a Code first instruction, a Use additional code instruction, 2 Excludes1 entries and 8 Excludes2 entries.

Code first

If the underlying condition listed here is present and known, sequence it first.

This code

Use additional code

Add the listed code as a secondary code, if known.

This code
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (2 notes)
Inherited from K50–K52 Noninfective enteritis and colitis

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (8 notes)
Inherited from Chapter 11 Diseases of the digestive system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Gastrointestinal tract and Genitourinary system clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Hospital CC

Counts as a complication or comorbidity (CC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 1 code in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C

Includes

Further defines or gives examples of the content of the category.

Also from chapter/block level (1 note)
Inherited from K50–K52 Noninfective enteritis and colitis
  • noninfective inflammatory bowel disease

Inclusion terms

Conditions classified to this code.

This code
  • Drug-induced gastroenteritis and colitis

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 18 entries

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