ICD-10 K04.4
Billable / Specific CCAcute apical periodontitis of pulpal origin
About ICD-10-CM K04.4
ICD-10-CM code K04.4 represents Acute apical periodontitis of pulpal origin. This is a billable/specific code in the Digestive System chapter (block K04). The 2026 edition of ICD-10-CM K04.4 became effective on October 1, 2025.
Coding Tips for K04.4
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
K04.4 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under K04.4. Per CMS ICD-10-CM Tabular 2026.
- Acute apical periodontitis NOS
Type 1 Excludes
Pure excludes, these codes can never be coded together with K04.4. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- acute periodontitis (K05.2-)
Inpatient DRG Impact, CC
codes Acute apical periodontitis of pulpal origin. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for K04.4
Local Coverage Determinations (LCDs) from CMS MACs that list K04.4 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 K04.4.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but K04.4 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with K04.4
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 K04.4 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 |
|---|---|---|
| K04.4 | 5224 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To K04.4
Other codes in section K00-K14 (Diseases of oral cavity and salivary glands).
ICD-10 K04.4, Billing FAQ
Is ICD-10 code K04.4 billable? +
Yes, K04.4 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to K04.4? +
ICD-10 K04.4 includes: Acute apical periodontitis NOS.
What codes are Type 1 Excludes for K04.4? +
Type 1 Excludes (never code together with K04.4): acute periodontitis (K05.2-)
Is K04.4 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does K04.4 map to? +
Per CMS GEMs, K04.4 maps to ICD-9 codes: 5224. 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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