Is an 8mm right lower calyceal non-obstructing renal stone with mild pelvocaliceal dilatation an indication for Extracorporeal Shock Wave Lithotripsy (ESWL)?

From the Guidelines

An 8 mm right lower calyceal non-obstructing renal stone with mild pelvocaliceal dilatation is generally indicated for ESWL (Extracorporeal Shock Wave Lithotripsy). ESWL is typically considered appropriate for stones between 5-20 mm, with optimal results for those under 10 mm, making this 8 mm stone a suitable candidate 1. The lower calyceal location may slightly reduce ESWL success rates compared to stones in other locations due to gravity-dependent drainage issues, but it remains a reasonable first-line approach.

Considerations for ESWL

• The presence of mild pelvocaliceal dilatation suggests some degree of urinary flow obstruction, which further supports intervention rather than watchful waiting.
• Before proceeding with ESWL, the patient should have a complete metabolic evaluation, urine culture to rule out infection, and assessment of stone composition if possible.
• Post-procedure, patients typically need pain management with NSAIDs or acetaminophen, adequate hydration (2-3 liters of water daily), and possibly alpha-blockers like tamsulosin 0.4 mg daily to facilitate stone fragment passage.
• Follow-up imaging at 2-4 weeks post-treatment is recommended to assess stone clearance.

Comparison with Other Treatment Options

• While URS (Ureteroscopy) is also an acceptable first-line treatment for ureteral stones, ESWL is often preferred for renal stones due to its less invasive nature and lower risk of complications 1.
• The choice between ESWL and URS should be based on individual patient factors, including stone size, location, and composition, as well as patient preferences and medical history.

Key Points to Consider

• ESWL is a suitable treatment option for an 8 mm right lower calyceal non-obstructing renal stone with mild pelvocaliceal dilatation.
• Patients should be counseled on the attendant risks and benefits of ESWL, including the potential for pain, infection, and the need for additional procedures 1.

From the Research

Indications for ESWL

• The patient has an 8 mm right lower calyceal non-obstructing renal stone with mild pelvocaliceal dilatation, which may be indicated for Extracorporeal Shock Wave Lithotripsy (ESWL) as the stone size is between 10 and 20 mm 2.
• ESWL is a treatment option for renal stones between 10 and 20 mm in size, excluding lower polar stones, unless the anatomy is favorable 2.
• Stone size and location are significant factors in determining the outcome of ESWL, with smaller stones and those in more accessible locations having better success rates 3, 4.

Considerations for ESWL

• The mean attenuation value (MAV) and skin-to-stone distance (SSD) can be useful in predicting treatment success, but their inclusion may not provide substantial advantages compared to relying solely on kidney-ureter-bladder film (KUB) 3.
• Traditional factors such as stone size, location, composition, and renal anatomy are important in predicting ESWL success 4.
• Nomograms and computed tomography attenuation values can help predict stone-free outcome after ESWL 4.

Alternative Treatment Options

• Flexible ureteroscopy can be an option for lower pole stones between 1.5 and 2 cm in size, especially in cases of difficult lower polar anatomy and ESWL-resistant stones 2.
• Percutaneous nephrolithotomy (PCNL) is generally recommended for stones larger than 20 mm², staghorn and partial staghorn calculi, and stones in patients with chronic kidney disease 2.
• Active monitoring may be employed in post-intervention residual stones, asymptomatic patients with no evidence of infection, and fragments less than 4 mm 2, 5.