Inclusion Criteria:

1. Patients with upper urinary tract calculi, where the maximum diameter of a single calculus or the cumulative diameter of multiple calculi is 1-3 cm
2. Patients who choose to undergo "flexible ureteroscopic holmium laser lithotripsy"
3. Aged 18-80 years, regardless of gender
4. Subjects without mental illness or language dysfunction, who can understand the details of this study and sign the informed consent form

Exclusion Criteria:

1. Patients with ureteral stricture or a history of ureteral stricture
2. Patients with a history of open renal and/or ureteral surgery or laparoscopic surgery
3. Fever (body temperature ≥ 38℃) due to urinary tract infection or other reasons within one week before surgery
4. Pregnant women, lactating women, or women who are in the menstrual period
5. ASA classification > Grade 3: patients with severe systemic diseases, heart diseases, pulmonary insufficiency, and failure of important organ functions, etc., who cannot tolerate anesthesia or surgery
6. Patients with anatomical malformations such as polycystic kidney, horseshoe kidney, and ectopic kidney
7. Patients with abnormal coagulation function (e.g., international normalized ratio (INR) > 1.5 or platelet count < 80 × 10⁹/L)
8. Patients with failed sheath placement during surgery