K52.9: Noninfective gastroenteritis and colitis, unspecified

Yes. K52.9 is a valid billable ICD-10-CM code at the fourth character. It is valid in the FY2026 code set and unchanged in the FY2027 update, effective 1 October 2026. The record should show a provider statement of colitis, gastroenteritis or another term from the inclusion list at K52.9. It should also show that no infectious cause was identified and that no named type applies, such as ulcerative, Crohn, indeterminate, microscopic, eosinophilic or ischemic.

Use A09 when the provider attributes the gastroenteritis or colitis to infection without naming an organism. Infectious colitis NOS is an inclusion term at A09. Use K52.9 when infection is not documented as the cause. The two codes carry reciprocal Excludes1 notes and are not reported together for the same condition. Where an organism is named, code the organism instead, for example A04.72 for enterocolitis due to Clostridium difficile not specified as recurrent.

No. K52.9 carries no CMS-HCC v28 category. No other code in category K52 maps to a v28 category either. The two inflammatory bowel disease categories in v28 are HCC 80 for Crohn's Disease (Regional Enteritis) and HCC 81 for Ulcerative Colitis. K51.90 maps to HCC 81, which is the mapping an unspecified colitis code forfeits.

Code microscopic colitis from K52.83, which is not billable on its own and requires a sixth character. Assign K52.831 for collagenous colitis, K52.832 for lymphocytic colitis, K52.838 for another named microscopic subtype and K52.839 when the pathology report names no subtype. The diagnosis rests on biopsy. NIDDK describes the inflammation of microscopic colitis as visible only when colon tissue is examined under a microscope. An endoscopic report alone does not support these codes.

K52.9 is not reported with any of the three for the same condition. K52.9 carries an Excludes1 note for diarrhea NOS (R19.7). Diarrhea integral to the colitis is not reported separately. K52.3 carries an Excludes1 note for unspecified colitis, which means K52.3 and K52.9 are not reported together for the same condition. A documented ulcerative colitis diagnosis is coded from the K51 codes and displaces K52.9 rather than accompanying it.

ICD-10-CM carries no unique code for segmental colitis associated with diverticulosis. The diverticular disease is reported from category K57, for example K57.30 for diverticulosis of large intestine without perforation or abscess without bleeding. No Excludes note stands between K52 and K57. Both may therefore be reported when the provider documents a diverticular disease and a separate colitis at the same encounter.

K52.9 may be the principal diagnosis when colitis is the condition established after study to be chiefly responsible for the admission. It is a secondary diagnosis when another condition better accounts for the encounter. In the inpatient setting a diagnosis documented at discharge as probable or suspected is coded as though it were confirmed, under UHDDS rules. In the outpatient setting only a confirmed diagnosis is coded. An uncertain colitis is reported there with the presenting sign or symptom instead, such as diarrhea, unspecified (R19.7).

K52.9 is unchanged in the FY2027 update, effective 1 October 2026, which adds, deletes or revises nothing in category K52. K52.9 was not revised in the FY2026 annual release, which took effect on 1 October 2025. No codes were added to or deleted from category K52 in FY2026. The April 1, 2026 mid-year addendum added no new diagnosis codes. No change affecting category K52 was identified in that addendum.