1. ICD-10-CM Codes
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2. K00-K95 Diseases of the digestive system
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3. K35-K38 Diseases of appendix
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4. K35- Acute appendicitis
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5. 2021 ICD-10-CM Diagnosis Code K35.33

2021 ICD-10-CM Diagnosis Code K35.33

Acute appendicitis with perforation and localized peritonitis, with abscess

2019 - New Code 2020 2021 Billable/Specific Code

• K35.33 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
• Short description: Acute appendicitis with perf and loc peritonitis, with abscs
• The 2021 edition of ICD-10-CM K35.33 became effective on October 1, 2020.
• This is the American ICD-10-CM version of K35.33 - other international versions of ICD-10 K35.33 may differ.

• 338 Appendectomy with complicated principal diagnosis with mcc
• 339 Appendectomy with complicated principal diagnosis with cc
• 340 Appendectomy with complicated principal diagnosis without cc/mcc
• 371 Major gastrointestinal disorders and peritoneal infections with mcc
• 372 Major gastrointestinal disorders and peritoneal infections with cc
• 373 Major gastrointestinal disorders and peritoneal infections without cc/mcc

• 2019 (effective 10/1/2018): New code
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change

• Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic) L02.91
  ICD-10-CM Diagnosis Code L02.91

  Cutaneous abscess, unspecified

  2016 2017 2018 2019 2020 2021 Billable/Specific Code
  • iliac (region) L02.214
    ICD-10-CM Diagnosis Code L02.214

    Cutaneous abscess of groin

    2016 2017 2018 2019 2020 2021 Billable/Specific Code
    • fossa K35.33
  • peritoneum, peritoneal (perforated) (ruptured) K65.1
    ICD-10-CM Diagnosis Code K65.1

    Peritoneal abscess

    2016 2017 2018 2019 2020 2021 Billable/Specific Code

    Applicable To

    • Abdominopelvic abscess
    • Abscess (of) omentum
    • Abscess (of) peritoneum
    • Mesenteric abscess
    • Retrocecal abscess
    • Subdiaphragmatic abscess
    • Subhepatic abscess
    • Subphrenic abscess
    • with appendicitis K35.33 - see also Appendicitis
  • appendix K35.33
  • cecum K35.33
  • ileocecal K35.33
  • periappendicular K35.33
  • pericecal K35.33
  • perityphlic K35.33
  • postcecal K35.33
  • subcecal K35.33
  • vermiform appendix K35.33
• Appendicitis (pneumococcal) (retrocecal) K37
  ICD-10-CM Diagnosis Code K37

  Unspecified appendicitis

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Type 1 Excludes

  • -unspecified appendicitis with peritonitis (K35.2-, K35.3-)
  • with
    • peritonitis NEC K35.33
      • localized K35.30
        ICD-10-CM Diagnosis Code K35.30

        Acute appendicitis with localized peritonitis, without perforation or gangrene

        2019 - New Code 2020 2021 Billable/Specific Code

        Applicable To

        • Acute appendicitis with localized peritonitis NOS
        • with
          • perforation K35.32
            ICD-10-CM Diagnosis Code K35.32

            Acute appendicitis with perforation and localized peritonitis, without abscess

            2019 - New Code 2020 2021 Billable/Specific Code

            Applicable To

            • (Acute) appendicitis with perforation NOS
            • Perforated appendix NOS
            • Ruptured appendix (with localized peritonitis) NOS
            • and abscess K35.33
    • peritoneal abscess K35.33
  • acute (catarrhal) (fulminating) (gangrenous) (obstructive) (retrocecal) (suppurative) K35.80
    ICD-10-CM Diagnosis Code K35.80

    Unspecified acute appendicitis

    2016 2017 2018 2019 2020 2021 Billable/Specific Code

    Applicable To

    • Acute appendicitis NOS
    • Acute appendicitis without (localized) (generalized) peritonitis
    • with
      • peritonitis NEC K35.33
        • localized K35.30
          ICD-10-CM Diagnosis Code K35.30

          Acute appendicitis with localized peritonitis, without perforation or gangrene

          2019 - New Code 2020 2021 Billable/Specific Code

          Applicable To

          • Acute appendicitis with localized peritonitis NOS
          • with
            • perforation K35.32
              ICD-10-CM Diagnosis Code K35.32

              Acute appendicitis with perforation and localized peritonitis, without abscess

              2019 - New Code 2020 2021 Billable/Specific Code

              Applicable To

              • (Acute) appendicitis with perforation NOS
              • Perforated appendix NOS
              • Ruptured appendix (with localized peritonitis) NOS
              • and abscess K35.33
      • peritoneal abscess K35.33
• Rupture, ruptured
  • cecum (with peritonitis) K65.0
    ICD-10-CM Diagnosis Code K65.0

    Generalized (acute) peritonitis

    2016 2017 2018 2019 2020 2021 Billable/Specific Code

    Applicable To

    • Pelvic peritonitis (acute), male
    • Subphrenic peritonitis (acute)
    • Suppurative peritonitis (acute)
    • with peritoneal abscess K35.33

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.