What is the best management approach for a patient with asymptomatic 12mm kidney stones in both the lower and upper pole of the right kidney?

Management of 12mm Kidney Stones in Lower and Upper Pole of Right Kidney

For asymptomatic 12mm kidney stones in both the lower and upper pole, ureteroscopy (URS) should be offered as first-line treatment, with percutaneous nephrolithotomy (PCNL) as an alternative option, while shock wave lithotripsy (SWL) should NOT be used due to unacceptably low success rates for stones >10mm. 1

Treatment Algorithm Based on Stone Size and Location

Why SWL is NOT Appropriate

• SWL should be explicitly avoided for stones >10mm as success rates drop dramatically to only 58% for 10-20mm stones, with significantly lower stone-free rates compared to other modalities 1
• Lower pole stones are particularly problematic for SWL due to gravity-dependent drainage issues and collecting system anatomy that prevents fragment clearance 1
• The 2025 guidelines from the American Urological Association state that for stones >10mm, SWL should NOT be offered as first-line therapy due to significantly lower success rates 1

First-Line Treatment Options

Ureteroscopy (URS):

• Median success rate of 81% for stones 10-20mm in the lower pole 1
• Higher stone-free rates (90%) compared to SWL (72%) for renal stones ≤20mm 1
• Can effectively treat both upper and lower pole stones in the same session 1
• Slightly higher complication rates than SWL, but this is acceptable given the superior efficacy 2

Percutaneous Nephrolithotomy (PCNL):

• Median success rate of 87% for lower pole stones 10-20mm 1
• Should be considered as first-line for total stone burden >20mm (which applies here with bilateral pole involvement) 1
• Flexible nephroscopy should be routinely performed during PCNL to access stone fragments in areas inaccessible by rigid nephroscope 1
• Normal saline irrigation must be used to prevent electrolyte abnormalities 1

Pre-Treatment Assessment

Mandatory Exclusions Before Surgery

• Rule out active infection: If obstructing stones with suspected infection are present, urgent drainage with stent or nephrostomy tube is mandatory before definitive treatment 1
• Ensure adequate renal functional reserve 2
• Verify no contraindications such as uncorrectable coagulopathy (for PCNL) or pregnancy 1

Factors Affecting Treatment Selection

• Body habitus and skin-to-stone distance affect SWL success (though SWL is already excluded for this size) 1
• Stone composition and density should be assessed if available 1
• Collecting system anatomy, particularly infundibular width and infundibulopelvic angle for lower pole stones 1

If Patient is Truly Asymptomatic

Active Surveillance Option

• European Association of Urology guidelines recommend active surveillance for asymptomatic, nonobstructing lower pole stones up to 15mm 1
• However, approximately 50% of asymptomatic stones will progress, and stones >15mm in the renal pelvis are at highest risk 3
• Stone size >7mm is a significant predictor of need for future surgical intervention 4, 5

Surveillance Protocol if Observation Chosen

• Follow-up imaging every 4-6 months for stones in this size range 6
• Monitor for development of symptoms, stone growth, or hydronephrosis 2
• Imaging studies should assess stone position and check for hydronephrosis 2

Common Pitfalls to Avoid

• Do not offer SWL as first-line therapy for 12mm stones—this is the most critical error to avoid, as success rates are unacceptably low 1
• Do not perform blind basket extraction without direct ureteroscopic vision 2
• Do not place routine stents after uncomplicated URS—this increases morbidity unnecessarily 1
• Do not delay treatment if infection is present—drain first, treat stone later 1

Patient Counseling Requirements

• Inform patient about all treatment modalities including relative benefits and risks 2
• Discuss stone-free rates: URS (81-90%), PCNL (87%), and why SWL is not appropriate 1
• Explain anesthesia requirements and need for potential additional procedures 2
• URS offers better chance of stone-free status with single procedure but has higher complication rates than SWL (though SWL is ineffective at this size) 2