Is ureteroscopy (URS) necessary for an asymptomatic kidney stone?

Management of Asymptomatic Kidney Stones

Ureteroscopy (URS) is not necessary for asymptomatic kidney stones and active surveillance is the recommended approach according to current guidelines. 1, 2

Evidence-Based Approach to Asymptomatic Kidney Stones

The American Urological Association (AUA) guidelines provide clear direction on the management of asymptomatic kidney stones:

• Active surveillance is recommended for patients with asymptomatic kidney stones when no interventional therapy is mandatory due to pain or medical factors 3
• Surgical intervention (URS, SWL, or PCNL) should be reserved for symptomatic stones or those causing obstruction/infection 1

Key Decision Factors

When evaluating asymptomatic kidney stones, consider:

1. Stone size and location:

   • Stones ≤4mm: High likelihood of spontaneous passage
   • Stones >7mm: Higher risk of future intervention, but still appropriate for observation if asymptomatic 4

2. Risk of progression:

   • Lower pole stones have lower spontaneous passage rates but can still be observed if asymptomatic
   • Stone growth rate should be monitored with periodic imaging

3. Patient factors:

   • Absence of symptoms (pain, hematuria, recurrent infections)
   • Normal renal function
   • No anatomical abnormalities that increase obstruction risk

Surveillance Protocol

For asymptomatic kidney stones under observation:

• Regular follow-up imaging (ultrasound or low-dose CT) at 6-12 month intervals
• Monitor for stone growth, development of symptoms, or signs of obstruction
• Metabolic evaluation to identify risk factors for stone formation
• Dietary modifications as appropriate (normal calcium intake, limited sodium, adequate hydration)

When Intervention May Be Warranted

Despite being asymptomatic, consider intervention if:

• Stone size increases significantly during observation
• Development of symptoms (pain, infection)
• Obstruction develops
• Patient preference after thorough counseling about risks/benefits

Treatment Options When Intervention Is Needed

If an asymptomatic stone requires treatment due to growth or other factors:

1. For stones ≤10mm:

   • SWL or URS are equally effective options with comparable stone-free rates 1, 5
   • A randomized controlled trial showed 90% stone-free rate with SWL and 92% with URS for lower pole stones <10mm 5

2. For stones >10mm and ≤20mm:

   • URS is preferred over SWL, especially for lower pole stones 1
   • Stone-free rates decline with SWL as stone size increases 1

3. For stones >20mm:

   • PCNL is the first-line therapy with highest stone-free rates 1, 6

Common Pitfalls to Avoid

1. Unnecessary intervention: Treating asymptomatic stones exposes patients to procedural risks without clear benefit to mortality or quality of life

2. Inadequate follow-up: Failing to monitor asymptomatic stones may lead to silent obstruction or infection

3. Overestimating benefits of prophylactic treatment: The majority of asymptomatic stones remain asymptomatic or pass spontaneously without intervention

4. Underestimating patient preferences: Some patients may prefer observation to avoid procedural risks, while others may prefer intervention to eliminate uncertainty

Conclusion

For asymptomatic kidney stones, active surveillance is the preferred initial approach based on current guidelines. URS and other interventional procedures should be reserved for stones that become symptomatic, show significant growth, or cause obstruction or infection. This approach minimizes unnecessary procedures while maintaining patient safety through appropriate monitoring.