Infectious gastroenteritis and colitis, unspecified (A09) ICD-10-CM
The A09 code range covers infectious gastroenteritis and colitis, unspecified with 1 ICD-10-CM diagnosis codes. 1 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
- Infectious colitis NOS
- Infectious enteritis NOS
- Infectious gastroenteritis NOS
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Codes in the A09 Range 1 codes · 1 billable
- A09 Infectious gastroenteritis and colitis, unspecified
About the A09 Code Range
The ICD-10 code A09 is used to classify cases of infectious gastroenteritis and colitis, unspecified. This code covers intestinal infections where the exact cause is not clearly identified but symptoms involve inflammation of the stomach and intestines.
This code applies to a broad range of gastrointestinal infections, often causing diarrhea and abdominal discomfort, and includes conditions commonly referred to as infectious diarrheal disease, acute gastroenteritis, infectious colitis, or infectious enteritis. It also encompasses infections linked to various microbes such as fungi (e.g., Aspergillus colitis) and parasites (e.g., Anisakis larva infection), as well as infections occurring in specific contexts like infectious gastroenteritis with AIDS or epidemic and institution-related outbreaks. The term “unspecified” indicates that precise pathogens are not identified, making A09 a practical code when detailed diagnostic information isn't available. Medical coders can rely on this code as a standardized classification for undetermined infectious inflammation of the digestive tract.
Questions About This Page
How many billable codes are in the A09 range?
Of the 1 codes in this range, 1 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the A09 range classify?
The range classifies infectious gastroenteritis and colitis, unspecified. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
