Pain relief after removal of non-obstructive renal calculi
Reviewed by Jay Khastgir

Non-obstructing stones are often not considered to be the source of pain, and probably most are not. This is because flank pain associated with a stone is typically caused by a stone that obstructs urinary flow, which increases intraluminal pressure and stretches nerve endings in the renal capsule and ureteric mucosa. When there is no collecting system dilatation the stone is considered non-obstructive and therefore not to be the source of pain. Yet, in certain patients, treatment of these apparently innocuous stones leads to pain relief. In this multicentre observational trial, the authors recruited 43 adult patients with renal stones up to 10mm in longest diameter without radiologic evidence of obstruction who had moderate to severe pain as assessed by their Brief Pain Inventory (BPI) score. Patients with mild pain or those with ureteric stones, nephrocalcinosis, moveable stones within the renal pelvis, presence of anatomical abnormalities such as calyceal diverticula, and those with clinical determined non-renal sources of pain were excluded. Ureteroscopic treatment of the non-obstructive stone(s) led to significant improvement in pain (BPI and patient-reported outcomes measurement) scores and the Wisconsin Stone Quality of Life questionnaire scores at 12 weeks postoperatively. Additionally, 86% and 69% of patients had at least a 20% and 50% reduction in pain respectively. This phenomenon requires further exploration, whether additional factors other than obstruction could cause pain in the absence of obstruction such as associated inflammatory changes, impaction within an infundibulum, or attachment of the stone to the mucosa. Although the authors did not identify such granular detail, it would still not help clinically identify those patients who may benefit from treatment and those who may not.

Prospective multicenter evaluation of pain before and after removal of nonobstructing renal calculi: A CoRE Initiative.
Bhojani N, Wollin DA, Tayeb MM, et al.
JOURNAL OF UROLOGY
2024;211:436–44.