Validation of non-stent criteria post-endoscopic stone management. Contemporary study

To validate the "5-Not's" (Hekal's) criteria for selecting candidates for stentless procedures following endoscopic urinary stone management, and to evaluate their applicability across both semi-rigid and flexible endoscopic modalities for renal and ureteral stones.

A cohort of 60 consecutive patients undergoing endoscopic treatment for urinary stones between October 2025 and March 2026 was enrolled. Exclusion criteria included severe obstructive hydronephrosis, concurrent urinary tract infection, a history of shockwave lithotripsy, and congenital urinary tract anomalies. All procedures were performed by a single surgeon without ureteral dilation. Patients were categorized based on whether they fulfilled the 5-Not's criteria (Group A, n = 23) or did not (Group B, n = 37). A stentless post-operative approach was the primary intent for all patients, with stent insertion performed only when clinically indicated. Stenting rates, secondary ureteroscopy requirements, and the diagnostic sensitivity and specificity of the criteria were evaluated.

Single stones were present in 95.6% of Group A and 83.8% of Group B cases (p = 0.164). Flexible ureteroscopy was utilized in 60.8% of Group A and 54.1% of Group B cases (p = 0.680). Postoperative ureteral stenting was required in 21.7% (5/23) of Group A patients and 43.2% (16/37) of Group B patients, p = 0.090. The combined criteria demonstrated an overall specificity of 76.2% and a sensitivity of 46.2%. Individually, the stone size cutoff ⩽ 8 mm yielded a sensitivity of 89.7% and a specificity of 52.3%, while the operative time cutoff ⩽ 40 min yielded a sensitivity of 92.3% and a specificity of 52.3%. The BMI cutoff ⩽ 27 demonstrated a sensitivity of 51.3% and a specificity of 57.1%.

The 5-Not's criteria provide a valid, reproducible, and clinically applicable framework for endoscopic urinary stone management. The criteria serve as a reliable confirmatory tool (high specificity) to safely select ideal candidates for stentless procedures, rather than an exclusive screening mechanism to rule out patients who fail to meet all five criteria.