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N20.2

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N20.2 - Calculus of Kidney with Calculus of Ureter

Short Description

N20.2: Use for kidney and ureter stones present in the SAME patient - when imaging confirms stones located in BOTH the kidney (renal pelvis/calyces) AND the ureter. This is a combination code representing bilateral location involvement in the same urinary tract pathway.

Full Description & Clinical Context

N20.2 describes urolithiasis affecting both the kidney and ureter - essentially a “two-site” stone condition where calculi are present in both anatomical locations simultaneously. This is fundamentally different from N20.0 (kidney only) or N20.1 (ureter only); N20.2 indicates stones at multiple levels of the urinary tract.

Key Clinical Concept:

  • N20.0 = kidney stone only (no ureter involvement)
  • N20.1 = ureter stone only (no kidney involvement)
  • N20.2 = stones in BOTH kidney AND ureter (same patient)

The distinction is critical for accurate coding: imaging must show stones in both locations to justify N20.2 coding.

Common Clinical Scenarios with N20.2:

  1. Primary stone in kidney that has migrated to ureter - Stone formed in renal pelvis has passed into ureter
  2. Independent stones at both sites - Separate stones in kidney AND separate stone in ureter
  3. Stone migration during passage - Larger stone partially in kidney, partially in ureter at time of imaging

Code Details

  • Code set: ICD-10-CM
  • Full code: N20.2
  • Title: Calculus of kidney with calculus of ureter
  • Code type: Billable/specific combination diagnosis code
  • Clinical category: urolithiasis (N20 block)
  • Inclusion terms: “Staghorn calculus” (may apply if branching stone extends into ureter)
  • Excludes 1: N13.2 (hydronephrosis with calculus)

⚠️ CRITICAL CODING RULE: Excludes 1 with N13.2

FUNDAMENTAL RULE: N20.2 has an Excludes 1 note with N13.2 (Hydronephrosis with calculus). This means:

  • You CANNOT report N20.2 and N13.2 together for the same encounter
  • Violating this rule = automatic claim denial

Decision Rule:

  • IF kidney + ureter stones WITHOUT hydronephrosis → Use N20.2
  • IF kidney + ureter stones WITH hydronephrosis → Use N13.2 instead (NOT N20.2)
  • IF unsure whether hydronephrosis present → Query provider for clarity

Example of INCORRECT coding:

  • ❌ N20.2 + N13.2 on same claim = automatic denial
  • ❌ N20.2 with documented hydronephrosis = compliance violation

Example of CORRECT coding:

  • ✅ N20.2 only when stones present without hydronephrosis
  • ✅ N13.2 only when hydronephrosis present (even if stones in both locations)

When to Use N20.2

Use N20.2 when ALL of the following are documented:

  1. Imaging evidence of stones in kidney: CT, ultrasound, or KUB showing calculus/calculi in renal pelvis or calyces
  2. Imaging evidence of stones in ureter: Same imaging modality confirming calculus/calculi within the ureter
  3. NO hydronephrosis documented: Critical - if swelling/obstruction of kidney present, use N13.2 instead
  4. Current encounter diagnosis: Active condition being evaluated/treated, not remote history

Common documentation phrases supporting N20.2:

  • “Stones in both right kidney and right ureter”
  • “Bilateral renal and ureteral calculi”
  • “Renal stone with secondary ureteral stone”
  • “Kidney stone has passed into ureter”
  • “2.5 cm lower pole stone and 1 cm proximal ureteral stone on left side”
  • “Right kidney with 3 mm staghorn calculus extending into proximal ureter”

When NOT to Use N20.2

Do NOT use N20.2 when:

  • Hydronephrosis is present: Use N13.2 instead (takes precedence)
  • Stone in kidney only: Use N20.0 instead
  • Stone in ureter only: Use N20.1 instead
  • Location not specified: Use N20.9 (unspecified urinary calculus) instead
  • Bladder stone present along with kidney/ureter stones: Consider N21.0 for bladder in addition to N20.2
  • Bilateral kidneys with bilateral ureters: Still use N20.2 (one code for bilateral condition)
CodeDescriptionWhen Used
N20.0Calculus of kidneyStone in kidney only; no ureter involvement
N20.1Calculus of ureterStone in ureter only; no kidney involvement
N20.2Calculus of kidney with calculus of ureterStones in BOTH kidney AND ureter
N20.9Urinary calculus, unspecifiedLocation unclear; avoid when more specific info available
N21.0Calculus in bladderBladder stone; may add to N20.2 if bladder also involved
N13.2Hydronephrosis with renal/ureteral calculous obstructionStones + hydronephrosis (takes precedence over N20.2)
N13.6Pyonephrosis with stoneObstructing stone + infection (most specific)
N23Unspecified renal colicRenal colic symptoms when stone NOT confirmed

Combination & Companion Code Patterns

Stone in Both Kidney AND Ureter (Same Side)

Scenario: 2.5 cm left kidney stone AND 1.8 cm left ureteral stone on same side

  • Coding: N20.2-LT (calculus of kidney with calculus of ureter, left)
  • NOT: N20.0-LT + N20.1-LT (these are included in N20.2)
  • Modifiers: Use -LT (left) or -RT (right) to indicate laterality

Bilateral Kidney/Ureter Stones (Both Sides)

Scenario: Right 3 cm kidney stone with right ureteral stone + Left 2.5 cm kidney stone with left ureteral stone

  • Coding: N20.2-50 (bilateral modifier) or separate N20.2-RT and N20.2-LT
  • Units: Typically report as single code with -50 modifier

Mixed Presentation (One Side Obstructing, One Side Non-obstructing)

Scenario:

  • Left obstructing stone with hydronephrosis
  • Right nonobstructing stone(s) in kidney and ureter

Coding:

  • N13.2-LT (left hydronephrosis with obstructing stone - takes precedence)
  • N20.2-RT (right kidney + ureter stones, no obstruction)

These are NOT excludes 1 violations because they’re on different sides with different clinical conditions

Kidney + Ureter Stone + Bladder Stone (Triple Site)

Scenario: Stone in right kidney, right ureter, AND bladder

  • N20.2-RT (kidney + ureter, right)
  • N21.0 (bladder stone - separate code, different site)

These are reportable together (different anatomical sites, not excludes 1)

Kidney + Ureter Stone + Hematuria

Scenario: Documented blood in urine caused by stones

  • N20.2 (primary: kidney + ureter calculus)
  • R31.9 (secondary: hematuria, unspecified) - if clinically significant and documented as related

HCC Information

  • N20.2 itself does NOT map to a CMS-HCC category and does not directly affect HCC-based risk adjustment
  • However, associated conditions if documented may have HCC implications:
    • N17.9 (Acute kidney failure) - if stone causes AKI → HCC 135
    • N18.x (Chronic kidney disease) - if pre-existing or develops → HCC 136/137

Coding guidance: Document complete clinical picture including any kidney function deterioration; focus primarily on accurate stone location coding

RVU / wRVU Applicability

  • ICD-10-CM diagnosis codes (including N20.2) do NOT carry RVUs or wRVUs
  • RVUs are assigned only to CPT/HCPCS procedure codes
  • N20.2 is used for DRG assignment, medical necessity justification, and severity documentation, not direct RVU generation

Common CPT Procedure Pairings with N20.2

CPTDescriptionWhen Used with N20.2
50080Percutaneous nephrolithotomy, simple (≤2 cm)Smaller kidney stone; ureteral stone handled separately
50081Percutaneous nephrolithotomy, complex (>2 cm)Larger kidney stone or staghorn
50590ESWL (extracorporeal shock wave lithotripsy)Non-invasive fragmentation of both stones
52356Ureteroscopy with laser lithotripsyUreteral stone removal; may be used with kidney stone code
52352Ureteroscopy with stone manipulationStone repositioning/extraction in ureter
52353ureteroscopy with basket extractionStone retrieval via basket
50436Dilation of existing nephrostomy tractPercutaneous access for kidney stone
50437Dilation with new nephrostomy placementNew drainage access for kidney stone
52332Cystoscopy with ureteral stent placementUrgent decompression if stones obstruct
9920xNew patient office E/MClinic evaluation of kidney + ureter stones
9921xEstablished patient office E/MFollow-up management

Clinical Examples & Scenarios

Scenario 1 - Single-Site Bilateral (Both Kidneys + Ureters)

Documentation: “Right 3 cm staghorn calculus in renal pelvis with involvement of upper pole calyx. Right proximal ureter shows 1.5 cm stone. Left kidney has 2.2 cm stone in lower calyx. Left ureter shows 1 cm stone.”

Coding:

  • ICD-10-CM: N20.2-50 (bilateral: calculus of kidney with calculus of ureter)
  • CPT (if treatment): 50081-50 (complex PCNL bilateral)

Why N20.2-50: Stones present bilaterally in both kidneys and ureters; bilateral modifier indicates both sides

Scenario 2 - Unilateral Left with Migrated Stone

Documentation: “Left kidney with 2.8 cm lower pole stone. Stone has migrated into proximal left ureter causing partial obstruction. No hydronephrosis. Right side without stones.”

Coding:

  • ICD-10-CM: N20.2-LT (calculus of kidney with calculus of ureter, left)
  • CPT: 50081-LT or 52356-LT depending on approach

Why N20.2-LT: Stones confirmed in both kidney and ureter on left; no hydronephrosis documented (so N13.2 not appropriate)

Scenario 3 - Right Obstructing (N13.2) + Left Non-obstructing (N20.2)

Documentation: “Right 2.5 cm upper pole stone with moderate hydronephrosis. Right ureteral stone causing obstruction. Left kidney has 1.5 cm stone and left ureter has 1 cm stone, no hydronephrosis, no obstruction.”

Coding:

  • ICD-10-CM:
    • N13.2-RT (right hydronephrosis with obstructing stone - primary)
    • N20.2-LT (left kidney + ureter calculus, non-obstructing - secondary)
  • CPT: 50081-50 (bilateral PCNL) or staged procedures

Why different codes on each side: Right meets N13.2 criteria (obstruction + hydronephrosis); left meets N20.2 criteria (no obstruction/hydronephrosis)

Scenario 4 - Kidney + Ureter + Bladder Stones

Documentation: “Right 2 cm kidney stone, right 1.2 cm ureteral stone, and 0.8 cm bladder stone identified on CT. No hydronephrosis.”

Coding:

  • ICD-10-CM:
    • N20.2-RT (right kidney + ureter calculus)
    • N21.0 (calculus in bladder - separate code for bladder location)
  • CPT: Depending on approach - could be 50080/50081 for kidney + 52356 for ureter + 52352 for bladder

Why multiple diagnosis codes: Different anatomical sites (kidney/ureter vs bladder) warrant separate codes

Scenario 5 - Pure Ureteral Stones (NOT N20.2)

Documentation: “1.8 cm stone in left proximal ureter and 1.2 cm stone in left mid-ureter. No kidney involvement. No hydronephrosis.”

Coding:

  • ICD-10-CM: N20.1-LT (calculus of ureter, left)
  • NOT: N20.2 (requires kidney stone to be present)
  • CPT: 52356-LT (ureteroscopy with lithotripsy)

Why NOT N20.2: Both stones are in the ureter; NO stone in kidney = use N20.1, not N20.2

Documentation Requirements & Best Practices

Essential Elements for N20.2

To support N20.2, provider documentation should clearly include:

✅ Confirmation of kidney stone: “Stone in kidney,” “renal calculus,” “pelvic stone,” “calyceal stone” ✅ Confirmation of ureteral stone: “Stone in ureter,” “ureteral calculus,” “stone in ureter” ✅ Imaging confirmation: “CT shows,” “ultrasound demonstrates,” “KUB reveals” stones at BOTH sites ✅ Stone size: Measured in millimeters or centimeters (influences CPT code: 50080 vs 50081) ✅ Laterality: Right, left, or bilateral ✅ Absence of hydronephrosis: Confirm no kidney swelling present (critical - if present, use N13.2 instead) ✅ Location specificity: Where in kidney (pelvis, which calyx), where in ureter (proximal, mid, distal)

Common Documentation Pitfalls for N20.2

❌ Assuming ureter stone migrated from kidney without clear documentation that both stones present ❌ No confirmation of ureteral stone location - vague documentation without imaging specification ❌ Hydronephrosis present but not documented as such - if swelling present, must use N13.2 ❌ Using N20.2 when only one site has stone - stone in kidney only = N20.0; ureter only = N20.1 ❌ Not confirming two separate stones vs migration - document whether stones are independent or related ❌ Missing laterality documentation - code N20.2 without -RT, -LT, or -50 modifier ❌ Confusing bilateral kidneys with bilateral involvement - N20.2 means stones in kidney AND ureter, not bilateral kidneys

Coding Tips & Pearls

💡 N20.2 = “Two-Site” Code: Kidney AND ureter both have stones; not bilateral kidneys 💡 Excludes 1 with N13.2: If hydronephrosis present, N13.2 takes precedence over N20.2 💡 Different sides = different codes: Right kidney+ureter (N20.2-RT) + left kidney+ureter (N20.2-LT) or N20.2-50 💡 Single code for bilateral: Use N20.2-50 for bilateral kidney/ureter involvement, not N20.2 × 2 💡 Stone migration documentation: Clearly state if stone passed from kidney to ureter or if independent stones 💡 Size matters for CPT: Measure in cm - affects 50080 (≤2 cm kidney) vs 50081 (>2 cm) selection 💡 Provider query if unclear: If documentation doesn’t clearly show stones in both locations, query provider 💡 Imaging is critical: CT/ultrasound must confirm stones at BOTH anatomical sites 💡 Don’t use N20.0 + N20.1: If stones at both sites, use N20.2 alone (it’s the combination code) 💡 Bladder involvement: If bladder stone also present, add N21.0 (separate code, different site)

Quick Reference Card

ICD-10-CM N20.2 - Calculus of Kidney with Calculus of Ureter
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✓ Use for: Stones in BOTH kidney AND ureter
✓ Requires: Imaging confirmation at both sites
✓ ⚠️ EXCLUDES 1: Cannot use N20.2 + N13.2 together
✓ If hydronephrosis: Use N13.2 instead (takes precedence)
✓ If kidney only: N20.0 (NOT N20.2)
✓ If ureter only: N20.1 (NOT N20.2)
✓ If bladder also: Add N21.0 (separate code)
✓ Laterality: -RT, -LT, or -50 (bilateral) required
✓ Bilateral modality: Use -50, not ×2
✓ Common CPT pairings: 50080/50081 (PCNL), 50590 (ESWL),
  52356 (ureteroscopy)
✓ Payable: YES (billable diagnosis code)
✓ RVU: No direct RVU; used for DRG/medical necessity

Excludes 1 Warning - Practice Exercise

Which is CORRECT coding?

A) N20.2 + N13.2
B) N20.2 only
C) N13.2 only

Scenario 1: “Patient with kidney stone AND ureteral stone, no hydronephrosis”

ANSWER: B) N20.2 only

  • ✅ N20.2 correctly describes stones at both sites without obstruction
  • ❌ Adding N13.2 violates Excludes 1 (and hydronephrosis not present anyway)
  • ❌ N13.2 alone would miss the fact that stones are at TWO sites

Scenario 2: “Patient with kidney stone AND ureteral stone WITH hydronephrosis”

ANSWER: C) N13.2 only

  • ✅ N13.2 is a combination code that includes stones + hydronephrosis (most specific)
  • ❌ N20.2 alone misses the obstruction/hydronephrosis component
  • ❌ Using both N20.2 + N13.2 violates Excludes 1 rule

Key principle: Excludes 1 violation = automatic denial

Last Updated: February 9, 2026
Created for clinical/coding reference - always verify against latest ICD-10-CM, payer policies, and facility guidelines
Critical for accurate multi-site urinary calculi coding

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