A09 - Infectious gastroenteritis and colitis, unspecified

Version 2023
Billable Code
Unspecified Code
MS-DRG Mapping
Convert to ICD-9
ICD-10:A09
Short Description:Infectious gastroenteritis and colitis, unspecified
Long Description:Infectious gastroenteritis and colitis, unspecified
Status: Valid for Submission
Version:ICD-10-CM 2023
Code Classification:
  • Certain infectious and parasitic diseases (A00–B99)
    • Intestinal infectious diseases (A00-A09)
      • Infectious gastroenteritis and colitis, unspecified (A09)

A09 is a billable ICD-10 code used to specify a medical diagnosis of infectious gastroenteritis and colitis, unspecified. The code is valid during the fiscal year 2023 from October 01, 2022 through September 30, 2023 for the submission of HIPAA-covered transactions.

Unspecified diagnosis codes like A09 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Clinical Information

Tabular List of Diseases and Injuries

The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more. The following references are applicable to this diagnosis code:


Inclusion Terms

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.

Type 1 Excludes

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.

Index to Diseases and Injuries References

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for this diagnosis code are found in the injuries and diseases index:

Convert to ICD-9 Code

Source ICD-10 CodeTarget ICD-9 Code
A09009.0 - Infectious enteritis NOS
Approximate Flag - The approximate mapping means there is not an exact match between the ICD-10 and ICD-9 codes and the mapped code is not a precise representation of the original code.

Patient Education


Gastroenteritis

Have you ever had the "stomach flu?" What you probably had was gastroenteritis - not a type of flu at all. Gastroenteritis is an inflammation of the lining of the intestines caused by a virus, bacteria, or parasites. Viral gastroenteritis is the second most common illness in the U.S. The cause is often a norovirus infection. It spreads through contaminated food or water or by contact with an infected person. The best prevention is frequent hand washing.

Symptoms of gastroenteritis include diarrhea, abdominal pain, vomiting, headache, fever, and chills. Most people recover with no treatment.

The most common problem with gastroenteritis is dehydration. This happens if you do not drink enough fluids to replace what you lose through vomiting and diarrhea. Dehydration is most common in babies, young children, older adults, and people with weak immune systems.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases


[Learn More in MedlinePlus]

Infectious Diseases

Germs, or microbes, are found everywhere - in the air, soil, and water. There are also germs on your skin and in your body. Many of them are harmless, and some can even be helpful. But some of them can make you sick. Infectious diseases are diseases that are caused by germs.

There are many different ways that you can get an infectious disease:

There are four main kinds of germs:

Infectious diseases can cause many different symptoms. Some are so mild that you may not even notice any symptoms, while others can be life-threatening. There are treatments for some infectious diseases, but for others, such as some viruses, you can only treat your symptoms. You can take steps to prevent many infectious diseases:


[Learn More in MedlinePlus]

Code History

Previous Code: A08.8

Next Code: A15