Objective To systematically analyze the application effect of a distal flexible negative pressure suction sheath in flexible ureteroscopy lithotripsy (URS) and its influences on surgical efficiency, postoperative stress, and inflammatory response.

Methods A total of 85 patients with renal calculi treated in the First Affiliated Hospital of Anhui University of Chinese Medicine from January 2020 to September 2025 were included as the study subjects and randomly divided into observation group (n=43) and control group (n=42). The observation group underwent URS using a distal flexible negative pressure suction sheath, while the control group underwent conventional URS. The surgical success rate (complete stone clearance rate), operation time, complications (such as bleeding and infection), and hospital stay were compared between the two groups. The levels of serum stress indicators norepinephrine (NE), adrenocorticotropic hormone (ACTH), and cortisol (Cor) and inflammatory indicators C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured 24 hours postoperatively.

Results All patients in both groups completed the surgery successfully without severe complications such as ureteral rupture or adjacent organ injury during or after the operation. Significant differences were observed between the two groups in terms of operation time, hospital stay, and the success rate of one-time lithotripsy (P < 0.05). In the observation group, among 33 patients with a stone diameter ≤ 20 mm, the stone clearance rate was 100.0% (33/33); among 10 patients with a stone diameter >20 mm, the stone clearance rate was 90.0% (9/10); the overall stone clearance rate was 97.67% (42/43). In the control group, among 34 patients with a stone diameter ≤ 20 mm, the stone clearance rate was 100.0% (34/34); among 8 patients with a stone diameter >20 mm, the stone clearance rate was 75.0% (6/8); the overall stone clearance rate was 95.24% (40/42). No significant differences were observed between the two groups in terms of the stone clearance rates for different stone diameters and the overall stone clearance rate (P>0.05). The complication rate was 2.33% (1/43) in the observation group, which was significantly lower than 16.67% (7/42) in the control group (P < 0.05). The levels of NE, ACTH, and Cor in the observation group were lower significantly than those in the control group (all P < 0.05). The levels of IL-6, TNF-α, and CRP in the observation group were significantly lower than those in the control group (all P < 0.05).

Conclusion By improving the sheath structure and drainage mode, the distal flexible negative pressure suction sheath for flexible ureteroscopy can enhance surgical accessibility and stone clearance efficiency, reduce postoperative stress and inflammatory response, and has potential application value in cases with larger or complex stones.