What is the recommended number of shocks for Extracorporeal Shock Wave Lithotripsy (ESWL)?

Recommended Number of Shocks for ESWL

Hundreds to thousands of shock waves are required to adequately fragment kidney stones during ESWL, with typical treatment protocols ranging from 2,000-4,500 shocks depending on stone location and size. 1

Standard Shock Wave Protocols by Stone Location

Renal Calculi

• 2,000-3,500 shocks are typically administered for kidney stones 2
• Treatment duration: 20-35 minutes 2
• The AUA guidelines confirm that "hundreds, or sometimes thousands" of shock waves are necessary for adequate stone fragmentation 1

Ureteral Calculi

• 3,000-4,500 shocks are typically required for ureteral stones 2
• Treatment duration: 30-45 minutes 2
• Higher shock numbers reflect the increased difficulty in fragmenting stones in the ureter compared to the kidney 2

Optimizing Shock Wave Delivery for Better Outcomes

Energy Escalation Strategy (Preferred Approach)

Use a stepwise voltage ramping protocol rather than fixed high-voltage treatment to improve stone-free rates and minimize renal injury. 3, 4

• Start with 500 shocks at 14 kV, then 1,000 shocks at 16 kV, followed by 1,000 shocks at 18 kV 4
• This escalating strategy achieves 81% stone-free rates compared to only 48% with fixed high-voltage protocols 4
• Stepwise energy ramping significantly reduces renal damage as measured by urinary biomarkers (beta2-microglobulin and microalbumin) 3, 4

Shock Wave Frequency Optimization

Decrease shock wave frequency from 120 to 60-90 shocks per minute to improve stone-free rates and reduce tissue damage. 3

• Slower delivery rates allow better stone fragmentation while minimizing collateral renal injury 3
• This represents a critical technical modification that directly impacts both efficacy and safety 3

Practical Treatment Range Across Different Lithotriptors

Clinical experience with various lithotriptor models demonstrates the following shock wave ranges:

• Dornier HM3/4 and modern systems: 793-8,000 shocks (mean 3,673 shocks) 5
• MPL 9000 technology: 610-4,000 shocks at 14-24 kV (usual energy 18 kV) 6
• Dornier DoLi 50: 2,500 shocks for fixed protocols or escalating protocols as described above 4

Critical Technical Considerations

Factors Affecting Total Shock Number

• Stone size: Larger stones require more shocks; stones >2 cm may need multiple sessions 6
• Stone composition: Harder stones (calcium oxalate monohydrate, cystine) require more energy and potentially more shocks 1
• Lithotriptor generation: Second and third-generation machines with smaller focal zones may require more shocks than the original Dornier HM-3 1

Session Management

• Re-treatment rates: 45.8% of patients require multiple sessions, with 54.2% achieving success in one session 6
• Multiple session approach: When needed, repeat treatments are preferable to excessive shocks in a single session to minimize cumulative renal injury 3

Common Pitfalls to Avoid

• Avoid fixed high-voltage protocols: Starting at maximum voltage (18 kV) throughout the entire treatment increases renal injury without improving stone-free rates 4
• Do not exceed safe shock wave rates: Delivering shocks at 120/minute or faster reduces efficacy and increases tissue damage 3
• Ensure proper acoustic coupling: Air pockets between the treatment head and skin deflect shockwaves, requiring more total shocks and reducing efficacy 3
• Recognize operator experience matters: Inexperienced operators may deliver more shocks due to poor targeting, increasing both treatment time and tissue injury 3