ICD-10 N21.0
Billable / SpecificCalculus in bladder
About ICD-10-CM N21.0
ICD-10-CM code N21.0 represents Calculus in bladder. This is a billable/specific code in the Genitourinary System chapter (block N21). The 2026 edition of ICD-10-CM N21.0 became effective on October 1, 2025.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under N21.0. Per CMS ICD-10-CM Tabular 2026.
- Calculus in diverticulum of bladder
- Urinary bladder stone
Type 2 Excludes
Not included here, the excluded code is not part of N21.0, but a patient may have both conditions at the same time. Both codes may be coded together when applicable.
- staghorn calculus (N20.0)
Medicare LCD Coverage for N21.0
Local Coverage Determinations (LCDs) from CMS MACs that list N21.0 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 N21.0.
1 Cigna
CPT Codes Commonly Billed with N21.0
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 52000 Cystoscopy diagnostic — bladder neck obstruction, cystitis, hematuria, hydronephrosis, bladder cancer, BPH, urinary retention, urethral stricture, poor stream, bladder calculus Urology
Convert N21.0 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 |
|---|---|---|
| N21.0 | 5940 | 10000 |
| N21.0 | 5941 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To N21.0
Other codes in section N20-N23 (Urolithiasis).
ICD-10 N21.0, Billing FAQ
Is ICD-10 code N21.0 billable? +
Yes, N21.0 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 N21.0? +
ICD-10 N21.0 includes: Calculus in diverticulum of bladder; Urinary bladder stone.
What codes are Type 2 Excludes for N21.0? +
Type 2 Excludes (may be coded together when both conditions exist): staghorn calculus (N20.0)
What CPT codes are commonly billed with N21.0? +
Procedures frequently paired with N21.0 include: 52000.
What ICD-9 codes does N21.0 map to? +
Per CMS GEMs, N21.0 maps to ICD-9 codes: 5940, 5941. 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 July 16, 2026.
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