What are the indications for Extracorporeal Shock Wave Lithotripsy (ESWL) and surgery in patients with renal and ureteric calculi?

Indications for ESWL and Surgery in Renal and Ureteric Calculi

For renal stones >20mm, percutaneous nephrolithotomy (PCNL) is first-line treatment; for stones <20mm in the renal pelvis or upper/middle calyx, flexible ureteroscopy (fURS) and ESWL are both first-line options, while for distal ureteric stones >10mm, ureteroscopy is first-line therapy. 1, 2

Renal Stones: Treatment Algorithm by Size and Location

Stones <10mm

• Lower pole stones <10mm: fURS or ESWL are primary treatment options 1
• Renal pelvis/upper/middle calyx <10mm: fURS or ESWL as first-line treatments 1
• Active surveillance is acceptable for asymptomatic, non-obstructing stones up to 15mm with periodic imaging follow-up 1

Stones 10-20mm

• Renal pelvis/upper/middle calyx 10-20mm: fURS and ESWL remain first-line, though EAU and SIU/ICUD guidelines add PCNL as another option 1
• Lower pole stones 10-20mm: fURS and PCNL are the suggested options; ESWL should not be offered as first-line therapy for lower pole stones >10mm 1, 2
• The rationale is that ESWL has poor stone-free rates for lower pole stones >10mm due to unfavorable anatomy for fragment passage 1

Stones >20mm

• PCNL is first-line treatment regardless of stone location 1, 2
• PCNL achieves 94% stone-free rates compared to 75% with URS for stones >20mm 2
• PCNL provides the highest stone-free rates and is less dependent on stone composition, density, and location compared to other modalities 2

Ureteric Stones: Treatment Algorithm by Location and Size

Distal Ureteric Stones

• Stones >10mm: Ureteroscopy (URS) is first-line therapy with superior stone-free rates (90% vs 72% for ESWL) 1
• Stones <10mm: URS is recommended as first-line per AUA/ES guidelines, while EAU and SIU/ICUD consider ESWL equivalent to URS 1
• Conservative management with observation is acceptable for stones <6-10mm if symptoms are controlled, with maximum duration of 4-6 weeks 1

Mid and Proximal Ureteric Stones

• URS is recommended as first-line treatment regardless of stone size 1
• Exception: SIU/ICUD guidelines recommend ESWL as first-line for proximal stones >10mm, and consider ESWL equivalent to URS for proximal stones <10mm 1

Absolute Indications for Intervention (Not Observation)

Surgical treatment is mandatory in these scenarios:

• Symptomatic stones with uncontrolled pain 1
• Obstructing stones causing hydronephrosis 1
• Stone growth on surveillance imaging 1
• Associated infection - urgent decompression via percutaneous nephrostomy or ureteral stenting is required before definitive treatment 2
• Vocational reasons (e.g., pilots, military personnel) 1

Special Stone Considerations

Stone Composition

• Cystine or uric acid ureteral stones: URS is recommended over ESWL 1
• Hyperdense stones (>1000 Hounsfield units): ESWL has poor results; flexible URS is preferred 3

Clinical Scenarios

• Patients on anticoagulation who cannot stop therapy: fURS is recommended over other modalities 1
• Suspected infection with obstructing stone: Drainage takes absolute priority over stone removal until infection resolves 2

Comparative Outcomes: ESWL vs URS

Stone-Free Rates

• URS achieves significantly higher single-procedure stone-free rates (90% vs 72%) across most stone locations 1
• ESWL for stones <10mm: 97% stone-free rate at 3 months (may require multiple sessions) 4
• ESWL for stones 10-15mm: 97% stone-free rate 4
• ESWL for stones >15mm: 90% stone-free rate 4

Morbidity and Complications

• ESWL has the least morbidity and lowest complication rate but requires more repeat procedures 1
• URS has higher complication rates including ureteral injury (3-6%) and stricture (1-4%) compared to ESWL 1
• In pediatric populations, flexible URS shows higher stone-free rates than ESWL with no difference in complication rates, though operative times and hospital stays are longer 1

Technical Considerations

ESWL-Specific

• Routine pre-stenting before ESWL is not recommended 1
• Alpha-blockers after ESWL facilitate passage of stone fragments 1
• If initial ESWL fails, endoscopic approach is recommended 1

URS-Specific

• Routine pre-stenting before URS is not recommended 1
• Post-URS stenting may be omitted if no ureteral injury, no stricture, normal contralateral kidney, no renal impairment, and no planned secondary procedure 1
• Alpha-blockers and anti-muscarinics reduce stent discomfort if stenting is performed 1

Critical Pitfalls to Avoid

• Do not offer ESWL for lower pole stones >10mm as first-line - poor fragment clearance leads to suboptimal outcomes 1, 2
• Do not delay intervention beyond 6 weeks for obstructing stones to avoid irreversible kidney injury 1
• Do not attempt definitive stone treatment in infected, obstructed systems - drain first, treat stone later 2
• Obtain urine culture before any procedure and treat bacteriuria; antibiotic prophylaxis is mandatory for URS and PCNL but not for ESWL in low-risk patients 1, 2