Lithotripsy, extracorporeal shock wave (ESWL)
Audit Defense & Denial Intelligence
Research-based denial patterns from OrbDoc Bill Analyzer
1. Stone size outside optimal range for ESWL (<5mm or >20mm)
Very Common50590 (shock wave lithotripsy) denials occur when kidney stone size is outside optimal treatment range. Stones <5mm should pass spontaneously with medical management. Stones >20mm have poor fragmentation success with ESWL - ureteroscopy or percutaneous nephrolithotomy more appropriate.
Common Causes
- • Stone <5mm - insurance expects conservative management (hydration, pain control, MET)
- • Stone >20mm - ESWL success rate too low, more invasive procedure appropriate
- • CT scan doesn't clearly show stone size in mm
Resolution Strategy
For stones <5mm: Appeal arguing patient cannot tolerate conservative management (severe pain despite narcotics, inability to work, recurrent ER visits), stone not passing after 4-6 weeks observation, or complicating factors (single kidney, transplant kidney, bilateral stones). For stones >20mm: Do not appeal ESWL denial - pursue alternative procedure (ureteroscopy 52353, PCNL 50080) with appropriate pre-authorization. For borderline sizes (18-22mm), appeal with stone composition data (CT Hounsfield units) showing favorable fragmentation characteristics and arguing patient preference for less invasive approach.
2. Failed conservative management not documented (stone passage trial)
CommonFor stones 5-10mm, many insurers require documented trial of medical expulsive therapy (MET) with tamsulosin before approving ESWL. Denials occur when immediate ESWL requested without showing patient tried and failed conservative stone passage.
Common Causes
- • ESWL requested without tamsulosin trial (alpha blocker to facilitate passage)
- • Conservative management <4 weeks - insufficient time for passage attempt
- • No documentation of pain management and hydration trial
Resolution Strategy
Appeal with documentation showing: trial of tamsulosin 0.4mg daily for 2-4 weeks without stone passage (prescription records, patient follow-up showing stone unchanged on imaging), adequate hydration attempted (patient educated, compliance documented), pain requiring narcotics (prescription records, ER visits), inability to work or function (work notes, activity restrictions), or urgent indications bypassing conservative management (fever >101°F suggesting infection, AKI, uncontrolled pain despite narcotics, solitary kidney). If no conservative trial attempted, may need to delay procedure for MET trial unless urgent indications documented.
3. Stone composition not favorable for ESWL fragmentation
OccasionalESWL success depends on stone composition. Calcium oxalate stones fragment well. Cystine and calcium phosphate monohydrate stones are very hard and resist fragmentation. Some insurers deny ESWL when CT Hounsfield units suggest unfavorable stone composition.
Common Causes
- • Cystine stones (HU >1000) - very resistant to shock wave fragmentation
- • Stone density >1000 HU on CT suggesting hard composition
- • Prior failed ESWL same patient/stone type - suggests unfavorable composition
Resolution Strategy
If stone composition unfavorable (HU >1000, known cystine or brushite stone, prior failed ESWL), appeal unlikely successful. Alternative procedures more appropriate: ureteroscopy with laser lithotripsy (52353) for most stone types, or PCNL (50080) for large/complex stones. If stone composition unknown, appeal arguing: no prior 24-hour urine stone analysis available to determine composition, CT HU <1000 suggesting favorable fragmentation, patient preference for least invasive approach with understanding may need secondary procedure if ESWL fails.
Relative Value Units (RVUs)
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Clinical Information
When to Use
Non-invasive treatment of kidney stones using external shock waves to fragment stones
Common Scenarios
Documentation Requirements
- CT scan or KUB X-ray showing stone size and location
- Stone size (typically 5-20mm for ESWL)
- Failed conservative treatment (hydration, pain control, medical expulsion therapy)
- Pre-procedure renal function tests
- Operative report describing number of shock waves and stone targeting
Coding Guidelines
Common Modifiers
Bundling Rules
- Includes fluoroscopic or ultrasound guidance
- Post-procedure imaging (KUB) separately billable if performed later
- Cannot bill multiple units for same stone in single session
- Anesthesia separately billable by anesthesiologist
Exclusions
- Do not use for bladder stones (use cystolithotripsy codes)
- Cannot bill if stone <5mm (should pass spontaneously)
- Do not use for stone >20mm (ureteroscopy or PCNL usually required)
- Cannot bill if procedure aborted before shock waves delivered
Coding Notes
Clinical scenarios
- CT scan or KUB X-ray showing stone size and location
- Stone size (typically 5-20mm for ESWL)
- Failed conservative treatment (hydration, pain control, medical expulsion therapy)
- CT scan or KUB X-ray showing stone size and location
- Stone size (typically 5-20mm for ESWL)
- Failed conservative treatment (hydration, pain control, medical expulsion therapy)
- CT scan or KUB X-ray showing stone size and location
- Stone size (typically 5-20mm for ESWL)
- Failed conservative treatment (hydration, pain control, medical expulsion therapy)
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Code Details
Medicare Pricing
PFSRVU Breakdown
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Ask a QuestionFrequently Asked Questions
CPT 50590 is the billing code for "Lithotripsy, extracorporeal shock wave (ESWL)". Non-invasive treatment of kidney stones using external shock waves to fragment stones
Medicare pays approximately $716.80 for CPT 50590 (national average). Actual payment varies by geographic location due to GPCI adjustments. Hospital and commercial insurance rates are typically 2-4x higher than Medicare rates.
CPT 50590 has a total RVU of 49.80, broken down as: Work RVU 5.20, Practice Expense RVU 42.80, and Malpractice RVU 1.80. RVUs (Relative Value Units) determine Medicare reimbursement rates.
The most common denial reason for CPT 50590 is "Stone size outside optimal range for ESWL (<5mm or >20mm)". 50590 (shock wave lithotripsy) denials occur when kidney stone size is outside optimal treatment range. Stones <5mm should pass spontaneously with medical management. Stones >20mm have poor fragmentation success with ESWL - ureteroscopy or percutaneous nephrolithotomy more appropriate. Common causes include: Stone <5mm - insurance expects conservative management (hydration, pain control, MET); Stone >20mm - ESWL success rate too low, more invasive procedure appropriate. Appeal success rate is approximately 10-30%.
Key documentation requirements for CPT 50590 include: CT scan or KUB X-ray showing stone size and location; Stone size (typically 5-20mm for ESWL); Failed conservative treatment (hydration, pain control, medical expulsion therapy); Pre-procedure renal function tests. Missing or incomplete documentation is a leading cause of claim denials for this code.
Bundling considerations for CPT 50590: Includes fluoroscopic or ultrasound guidance. Post-procedure imaging (KUB) separately billable if performed later Use an NCCI bundling checker to verify specific code combinations before billing.
Common modifiers for CPT 50590 include: 50 (Bilateral stones (both kidneys)), RT (Right kidney stone), LT (Left kidney stone). Modifiers indicate special circumstances and can affect reimbursement or prevent claim denials.
The typical time requirement for CPT 50590 is 60-90 minutes including positioning and imaging. Time-based codes require documentation of the actual time spent providing the service.