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    v1.0.28
    OpenPayerBilling CodesIntestinal infectious diseasesICD-10-CM a09-infectious-gastroenteritis-and-colitis
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    ICD-10-CM Code For Infectious Gastroenteritis And Colitis, Unspecified: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group A09 includes unspecified infectious gastroenteritis and colitis cases, acute diarrheal illnesses, and intestinal infections when a causative organism has not been determined or documented. These ICD-10-CM diagnosis codes are used to document acute infectious presentations of the gastrointestinal tract, capturing disease acuity, clinical complexity, and lack of identified pathogen. Accurate coding within the ICD-10-CM A09 group supports proper claim adjudication and complete clinical documentation for appropriate reimbursement.

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    ICD-10-CM A09: Infectious Gastroenteritis And Colitis, Unspecified Overview

    This group represents acute infectious inflammation of the gastrointestinal tract, including gastroenteritis and colitis when a specific pathogen is not identified. It targets the digestive system and covers presentations such as acute diarrhea and intestinal infection without a specified organism. Accurate coding matters for proper clinical documentation and for supporting reimbursement processes tied to diagnosis specificity.

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    When to Use

    Use a code from this group when a patient presents with symptoms of acute gastroenteritis or colitis and the medical record documents an infectious process but no specific organism is identified. These codes are appropriate for encounters where the clinical focus is symptomatic infectious inflammation of the gastrointestinal tract without pathogen-specific confirmation.

    ICD-10-CM Codes

    1 rows

    ICD-10-CM CodeDescription
    A09Infectious gastroenteritis and colitis, unspecified

    DRG Codes

    2 rows

    DRG CodeDescription
    391Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders with MCC
    392Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders without MCC

    Typical Clinical Scenarios

    • An otherwise healthy adult presents to the urgent care with acute onset of watery diarrhea, nausea, abdominal cramping, and low-grade fever that began 24 hours after attending a group picnic; history is notable for multiple similar cases among attendees suggesting a presumed foodborne viral or bacterial enteritis. Stool testing is not yet available and treatment is supportive; the clinician assigns a diagnosis from this group for acute infectious gastroenteritis while awaiting or without confirmatory pathogen identification. Typical codes: A09.
    • An elderly nursing home resident develops sudden profuse diarrhea and dehydration requiring hospitalization, with negative initial stool cultures for common bacterial pathogens and a clinical picture consistent with infectious colitis of uncertain etiology; management focuses on fluid resuscitation and infection control precautions in the facility. Because the causal organism is not identified but the presentation is consistent with an intestinal infection, a code from this group is used to document the infectious gastroenteritis/colitis. Typical codes: A09.
    • A young child with sickle cell disease is seen in clinic for persistent intermittent loose stools and abdominal pain for two weeks after a recent gastroenteritis outbreak at daycare; symptoms are prolonged but stool studies are inconclusive for a specific organism. The clinician documents ongoing infectious gastroenteritis/colitis as the reason for continued monitoring and symptomatic care, assigning a code from this group when no definitive pathogen is established. Typical codes: A09.

    Related Codes

    A00-CHOLERA

    ICD-10-CM Code For Cholera: Group Overview

    A01-TYPHOID-AND-PARATYPHOID-FEVERS

    ICD-10-CM Code For Typhoid And Paratyphoid Fevers: Group Overview

    A02-OTHER-SALMONELLA-INFECTIONS

    ICD-10-CM Code For Other Salmonella Infections: Group Overview

    A03-SHIGELLOSIS

    ICD-10-CM Code For Shigellosis: Group Overview

    A04-OTHER-BACTERIAL-INTESTINAL-INFECTIONS

    ICD-10-CM Code For Other Bacterial Intestinal Infections: Group Overview

    A05-OTHER-BACTERIAL-FOODBORNE-INTOXICATIONS

    ICD-10-CM Code For Other Bacterial Foodborne Intoxications Not Elsewhere Classified: Group Overview

    A06-AMEBIASIS

    ICD-10-CM Code For Amebiasis: Group Overview

    A07-OTHER-PROTOZOAL-INTESTINAL-DISEASES

    ICD-10-CM Code For Other Protozoal Intestinal Diseases: Group Overview

    Coming soon

    A08-VIRAL-AND-OTHER-SPECIFIED-INTESTINAL-INFECTIONS

    ICD-10-CM Code For Viral And Other Specified Intestinal Infections: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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