Impact of DJ stenting on subacute renal recovery after flexible ureterorenoscopy

Routine ureteral stenting after flexible ureterorenoscopy (F-URS) remains controversial. While stents are used to secure drainage, their impact on subclinical renal tubular injury is not well defined. This study aimed to evaluate the effect of postoperative Double-J (DJ) stenting on acute and subacute renal injury using urinary Kidney Injury Molecule-1 (KIM-1) as a sensitive biomarker.

We conducted a retrospective analysis of a prospectively maintained database including 117 patients who underwent F-URS for renal stones. To minimize selection bias, patients with severe ureteral injury (PULS Grade ≥ 3) were excluded, and a ureteral access sheath (UAS) was utilized in all cases to standardize intrarenal pressure. Patients were stratified into two groups according to the postoperative drainage strategy: Group 1 (DJ stent) and Group 2 (no stent). Urinary KIM-1 levels normalized to creatinine (KIM-1/Cr) were measured preoperatively, at the postoperative 4th hour (acute phase), and on day 14 (subacute phase).

Demographic characteristics and operative trauma scores (PULS) were comparable between the groups. In the acute phase (4th hour), both groups exhibited a significant and similar rise in KIM-1/Cr levels compared to baseline (p < 0.001), with no intergroup difference (p = 0.748). However, in the subacute phase (day 14), the stented group had significantly lower KIM-1/Cr levels compared to the non-stented group (0.18 vs. 0.36; p = 0.001). Additionally, the stone-free rate (SFR) was significantly higher in the stented group (89.8% vs. 65.5%; p = 0.002). Postoperative complication rates were similar (p = 0.35).

DJ stent placement does not alter the acute biomarker surge associated with surgical stress but is associated with significantly lower KIM-1/Cr levels during the subacute recovery period. This finding suggests that improved drainage, together with more effective stone clearance, may contribute to better tubular recovery in stented patients. Urinary KIM-1 serves as a valuable objective tool for monitoring subclinical renal injury and may guide individualized stenting decisions.