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    v1.0.28
    OpenPayerBilling CodesDiseases of peritoneum and retroperitoneumICD-10-CM k65-peritonitis
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    ICD-10-CM Code For Peritonitis: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group K65 includes diagnoses for peritonitis, covering acute bacterial peritonitis, spontaneous bacterial peritonitis, tuberculous peritonitis, and other specified or unspecified peritonitis. These ICD-10-CM diagnosis codes are used to document clinical scenarios that capture infection versus noninfectious inflammation, the extent of peritoneal involvement, and any underlying causes or complications relevant to care. Accurate coding within the ICD-10-CM K65 group supports proper claim adjudication and complete clinical documentation and appropriate reimbursement.

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    ICD-10-CM K65: Peritonitis Overview

    The ICD-10-CM K65 group captures peritonitis, which is inflammation or infection of the peritoneum and related retroperitoneal spaces. These diagnoses target the peritoneal lining of the abdominal cavity and are used for conditions ranging from localized bacterial peritonitis to generalized or tuberculous peritonitis. Accurate coding matters for proper clinical documentation and has implications for reimbursement because it reflects disease severity and treatment complexity.

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    When to Use

    Use a code from this group when clinical documentation indicates peritoneal inflammation or infection with specification of etiology or site when available. Select the most specific code that reflects whether the peritonitis is bacterial, tuberculous, postoperative, localized, or generalized, and include any documented complications.

    ICD-10-CM Codes

    7 rows

    ICD-10-CM CodeDescription
    K65.0Generalized (acute) peritonitis
    K65.1Peritoneal abscess
    K65.2Spontaneous bacterial peritonitis
    K65.3Choleperitonitis
    K65.4Sclerosing mesenteritis
    K65.8Other peritonitis
    K65.9Peritonitis, unspecified

    DRG Codes

    8 rows

    DRG CodeDescription
    371Major Gastrointestinal Disorders and Peritoneal Infections with MCC
    372Major Gastrointestinal Disorders and Peritoneal Infections with CC
    373Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC
    393Other Digestive System Diagnoses with MCC
    394Other Digestive System Diagnoses with CC
    395Other Digestive System Diagnoses without CC/MCC
    791Prematurity with Major Problems
    793Full Term Neonate with Major Problems

    Typical Clinical Scenarios

    • An adult presents to the emergency department with sudden-onset severe diffuse abdominal pain, high fever, guarding and rebound on exam, and tachycardia after suspected perforated viscus (e.g., perforated diverticulitis). Imaging shows free intraperitoneal air and fluid consistent with peritoneal inflammation; the team documents a primary bacterial inflammation of the peritoneal cavity requiring urgent surgical intervention and antibiotics. Typical codes: K65.0, K65.2
    • A patient on long-term peritoneal dialysis develops progressive cloudy dialysate, low-grade fever, and abdominal discomfort without signs of generalized sepsis; peritoneal fluid analysis yields elevated white blood cells and a positive culture for skin flora. Because the peritoneum is inflamed secondary to peritoneal dialysis-related infection, a peritonitis code specific to the infectious process is assigned. Typical codes: K65.1, K65.8
    • An elderly hospitalized patient with advanced malignancy and recent intra-abdominal surgery develops slow-onset abdominal distension, mild tenderness, and imaging showing sterile inflammatory fluid in the peritoneal cavity without clear infectious source, consistent with localized or chronic peritonitis as a complication/prolonged inflammatory response. A nonacute or unspecified peritonitis code is used to capture this comorbidity affecting clinical management. Typical codes: K65.3, K65.9

    Related Codes

    K66-OTHER-DISORDERS-OF-PERITONEUM

    ICD-10-CM Code For Other Disorders Of Peritoneum: Group Overview

    K67-DISORDERS-OF-PERITONEUM

    ICD-10-CM Code For Disorders Of Peritoneum In Infectious Diseases Classified Elsewhere: Group Overview

    K68-DISORDERS-OF-RETROPERITONEUM

    ICD-10-CM Code For Disorders Of Retroperitoneum: 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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