Can a 5 mm kidney stone located in the left lower pole cause pain in an older patient?

Can a 5mm Lower Pole Kidney Stone Cause Pain?

Yes, a 5mm kidney stone in the left lower pole can absolutely cause pain, even in the absence of obstruction, though the mechanism and likelihood differ from classic obstructing ureteral stones.

Pain Mechanisms in Lower Pole Stones

Non-Obstructing Stone Pain ("Small Stone Syndrome")

• Small non-obstructing calyceal stones (≤4mm) have been documented to cause significant flank pain requiring intervention 1
• In a study of patients with non-obstructing calyceal stones ≤4mm treated with ureteroscopy, 85% achieved complete pain resolution and 15% had partial resolution after stone removal, confirming these stones were the pain source 1
• Your 5mm stone is larger than the stones in this study, making it even more likely to cause symptoms 1

Detection and Clinical Significance

• Stones ≤5mm have historically been considered likely to pass spontaneously, but this does not mean they are asymptomatic 2
• Approximately 16-20% of small stones ≤5mm still require surgical intervention within 5 years, indicating they cause clinically significant problems 3
• The American College of Radiology recommends color Doppler with twinkling artifact assessment for small renal stones (<5mm) due to the clinical importance of detecting them 3

Location-Specific Considerations

Lower Pole Anatomy

• Lower pole stones are particularly problematic because gravity and unfavorable calyceal anatomy impede spontaneous passage 4
• For lower pole stones <10mm, flexible ureteroscopy (fURS) or shock wave lithotripsy (SWL) are primary treatment options, acknowledging these stones warrant intervention 4
• The European Association of Urology and Société Internationale d'Urologie guidelines specifically address lower pole stones separately, recognizing their unique clinical behavior 4

Pain Without Obstruction

Key Clinical Point

• The absence of hydronephrosis does not exclude a stone as the pain source 3
• Hydronephrosis has up to 100% sensitivity for ureteral obstruction, but lower pole stones may cause pain through mechanisms other than obstruction 3
• Within the first 2 hours of presentation, secondary signs of obstruction may not have developed yet 3

Proposed Mechanisms

• Local mucosal irritation and inflammation from the stone surface 1
• Microtrauma to the calyceal epithelium 1
• Intermittent partial obstruction not captured on static imaging 2

Clinical Implications for Older Patients

• Stone composition and metabolic factors become increasingly important with age, as recurrence rates are higher in patients with multiple previous episodes 4
• Older patients may have reduced pain perception, but this does not mean the stone is clinically insignificant 4
• If pain is present and attributable to the stone after excluding other causes, treatment should be considered regardless of obstruction status 1

Diagnostic Approach

• Confirm stone presence and size with imaging—CT is superior to ultrasound for accurate sizing, as ultrasound tends to overestimate stones ≤5mm 4, 3
• Assess for hydronephrosis, though its absence does not rule out the stone as pain source 3
• Consider metabolic evaluation in high-risk patients (family history, recurrent stones, single kidney) 5

Management Decision

• For a symptomatic 5mm lower pole stone causing pain, observation with medical expulsive therapy or definitive treatment (fURS or SWL) are both reasonable options 4
• Conservative management with periodic imaging is acceptable if pain is controlled, but follow-up duration should not exceed 4-6 weeks from initial presentation 4
• If pain persists despite conservative measures, ureteroscopic treatment has demonstrated 85-100% pain resolution rates for small non-obstructing stones 1