ICD-10 K35.3
Non-Billable HeaderAcute appendicitis with localized peritonitis
About ICD-10-CM K35.3
ICD-10-CM code K35.3 represents Acute appendicitis with localized peritonitis. This is a non-billable header code in the Digestive System chapter (block K35). The 2026 edition of ICD-10-CM K35.3 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Medicare LCD Coverage for K35.3
Local Coverage Determinations (LCDs) from CMS MACs that list K35.3 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing K35.3.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but K35.3 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with K35.3
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert K35.3 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| K35.3 | 5401 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To K35.3
Other codes in section K35-K38 (Diseases of appendix).
ICD-10 K35.3, Billing FAQ
Is ICD-10 code K35.3 billable? +
No, K35.3 is a non-billable header code. Use a more specific child code from block K35 when submitting claims.
What ICD-9 codes does K35.3 map to? +
Per CMS GEMs, K35.3 maps to ICD-9 codes: 5401. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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