ICD-10-CM 2027
ICD-10 code for infectious sigmoiditis
Infectious gastroenteritis and colitis, unspecified
From the official ICD-10-CM alphabetic index entry “Sigmoiditis › infectious”. Page updated September 29, 2026.
About coding infectious sigmoiditis
The ICD-10-CM code for infectious sigmoiditis is A09 (Infectious gastroenteritis and colitis, unspecified).
Don't report A09 together with the conditions in its Excludes1 note: colitis NOS (K52.9), diarrhea NOS (R19.7), enteritis NOS (K52.9), gastroenteritis NOS (K52.9) and 1 more.
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 391 (Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders with MCC, relative weight 1.2392) and DRG 392 (Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders without MCC, relative weight 0.7645), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Don't confuse with (Excludes1 for A09)
Common questions about infectious sigmoiditis ICD-10 codes
What is the ICD-10 code for infectious sigmoiditis?
- A09 — Infectious gastroenteritis and colitis, unspecified.
Is A09 billable?
- Yes. A09 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can A09 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict A09 as a principal diagnosis.
Is A09 a CC or MCC?
- A09 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.