Can non-obstructing kidney stones cause pain?

Non-Obstructing Kidney Stones Can Cause Pain

Yes, non-obstructing kidney stones can cause significant pain that may warrant treatment, even without causing urinary obstruction. 1

Evidence for Pain from Non-Obstructing Stones

• A 2024 multicenter, observational trial found that patients with small non-obstructing calyceal stones (up to 10mm) experienced significant pain reduction and improved quality of life after stone removal, with 86% of patients experiencing at least a 20% reduction in pain scores 1
• A 2013 study examining "small stone syndrome" demonstrated that ureteroscopic treatment of small non-obstructing calyceal stones (≤4mm) achieved complete or partial pain resolution in all patients studied, with 85% reporting complete pain resolution 2
• The natural history of small non-obstructing renal stones shows that symptoms develop in 7-77% of cases, even without obstruction 3

Mechanisms of Pain in Non-Obstructing Stones

• While renal colic is classically associated with urinary tract obstruction, non-obstructing calyceal stones can cause pain through several mechanisms:
  • Direct irritation of the renal collecting system 2
  • Microcrystal movement within the collecting system 1
  • Intermittent partial obstruction that may not be captured during imaging 2

Clinical Implications

• When evaluating patients with flank pain and non-obstructing stones, clinicians should:
  • Not dismiss the stones as an incidental finding simply because they are non-obstructing 1, 2
  • Consider stone removal as a treatment option for patients with persistent pain attributed to non-obstructing stones 1
  • Recognize that stone size does not necessarily correlate with pain severity in non-obstructing stones 2

Diagnostic Considerations

• Non-contrast CT is the reference standard for evaluating urolithiasis with a sensitivity as high as 97% 3
• Ultrasound may be used as an initial imaging modality but has lower sensitivity (24-57%) for stone detection compared to CT 3
• The absence of hydronephrosis on ultrasound makes the presence of a larger obstructing stone (>5mm) less likely but does not rule out symptomatic non-obstructing stones 3

Treatment Approach

• For symptomatic non-obstructing stones:
  • Surgical removal (typically ureteroscopy) should be offered as a treatment option for patients with persistent pain 1
  • Conservative management with increased fluid intake and pain control may be appropriate for some patients 4
  • Medical expulsive therapy is typically not indicated for non-obstructing calyceal stones as they are unlikely to pass spontaneously 5

Prevention of Recurrence

• Preventive measures should be implemented based on stone composition 4:
  • Increased fluid intake to maintain adequate urine output 5
  • Dietary modifications based on stone type 4
  • Treatment of any underlying metabolic abnormalities 6

Conclusion

The evidence clearly demonstrates that non-obstructing kidney stones can cause significant pain and impact quality of life. Treatment of these stones can provide substantial pain relief and should be considered in the management approach for symptomatic patients.