Impact of Forced Diuresis on the Residual Fragment Rate After Flexible Ureteroscopy for Management of Renal Stones

This randomized controlled clinical trial evaluated whether furosemide-assisted forced diuresis during flexible ureteroscopy reduced the residual fragment rate and improved stone clearance in patients with renal stones measuring up to 30 millimeters. Adult patients undergoing flexible ureteroscopy were randomized into two parallel groups: an experimental group that received intravenous furosemide during the procedure and a control group that received standard perioperative and postoperative care without furosemide. Residual stone fragments were assessed using low-dose non-contrast computed tomography on postoperative day 1 and at 6 weeks after the procedure. The primary outcome was the proportion of patients with residual stone fragments greater than 2 millimeters on postoperative day 1. Secondary outcomes included the proportion of patients with residual stone fragments greater than 2 millimeters at 6 weeks, operative time, postoperative complications, and the need for auxiliary treatment for clinically significant residual stones.

Study Overview

• Status: Completed
• Conditions: Kidney Stones
• Intervention / Treatment: Drug: Furosemide; Other: Standard Care After Flexible Ureteroscopy Without Furosemide

• Study Type: Interventional
• Enrollment (Actual): 200
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Cairo Governorate
    • Cairo, Cairo Governorate, Egypt, 11511
      • Ain Shams University Hospitals (Urology Department)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adult patients aged 18 years or older.
• Patients who underwent flexible ureteroscopy for renal stones measuring 30 millimeters or less.

Exclusion Criteria:

• Patients with active urinary tract infection.
• Patients with a history of previous open renal surgery or renal trauma.
• Patients with contraindications to anesthesia, such as severe cardiac disease, uncontrolled diabetes mellitus, or severe coagulation disorder.
• Patients with severe renal impairment, defined as an estimated glomerular filtration rate less than 30 milliliters per minute per 1.73 square meters.
• Known Ureteric stricture and pelvi-ureteric junction obstruction
• Patients with a single kidney.
• Patients with contraindications to furosemide administration.
• Patients with congenital renal anomalies.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Furosemide-Assisted Forced Diuresis During Flexible Ureteroscopy; During flexible ureteroscopy, participants received intravenous furosemide 40 milligrams total, divided into 20 milligrams administered 5 minutes after induction of anesthesia and 20 milligrams administered 30 minutes after the start of the procedure.	Drug: Furosemide; Intravenous furosemide was administered as a total dose of 40 milligrams during the procedure, divided into 20 milligrams given 5 minutes after induction of anesthesia and 20 milligrams given 30 minutes after the start of the procedure.
Active Comparator: Standard Care During Flexible Ureteroscopy Without Furosemide; Participants underwent flexible ureteroscopy and received standard perioperative and postoperative care without receiving intravenous furosemide or any other diuretic medication.	Other: Standard Care After Flexible Ureteroscopy Without Furosemide; Participants received standard perioperative and postoperative management after flexible ureteroscopy without administration of furosemide or any other diuretic medication.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of patients with residual stone fragments greater than 2 mm	Residual stone fragments were assessed using low-dose non-contrast computed tomography (CT) performed on postoperative day 1. The outcome was reported as the proportion of patients with one or more residual renal stone fragments measuring greater than 2 mm.	Postoperative day 1 after flexible ureteroscopy

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Operative time	Operative time was calculated from insertion of the ureteroscope into the urethra until completion of ureteral stent placement.	During procedure
Postoperative urinary tract infection	Postoperative urinary tract infection was assessed within seven days after the procedure using fever with urinary symptoms and or a positive urine culture with significant bacteriuria.	Within 7 days post-procedure
Need for auxiliary treatment for clinically significant residual stones	The need for auxiliary treatment for clinically significant residual stones was recorded, including extracorporeal shock wave lithotripsy or repeat ureteroscopy.	Up to 6 weeks after flexible ureteroscopy
Proportion of patients with residual stone fragments greater than 2 mm at 6 weeks	Residual stone fragments were assessed using low-dose non-contrast computed tomography (CT) performed 6 weeks after flexible ureteroscopy. The outcome was reported as the proportion of patients with one or more residual renal stone fragments measuring greater than 2 mm.	6 weeks after flexible ureteroscopy

Collaborators and Investigators

• Sponsor: Ain Shams University

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2026
• Primary Completion (Actual): July 1, 2026
• Study Completion (Actual): July 1, 2026

Study Registration Dates

• First Submitted: December 16, 2025
• First Submitted That Met QC Criteria: December 30, 2025
• First Posted (Actual): January 13, 2026

Study Record Updates

• Last Update Posted (Actual): August 18, 2026
• Last Update Submitted That Met QC Criteria: August 15, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: furosemide; nephrolithiasis; ureteroscopy; Kidney stones; flexible ureteroscopy; renal calculi; non-contrast computed tomography; laser lithotripsy; stone-free rate; residual stone fragments; forced diuresis
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urolithiasis; Urinary Calculi; Pathological Conditions, Signs and Symptoms; Kidney Calculi; Nephrolithiasis; Sulfur Compounds; Organic Chemicals; Amides; Aniline Compounds; Amines; Sulfonamides; Sulfanilamides; Sulfones; Furosemide
• Other Study ID Numbers: FMASU MS 686/2025

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data that underlay the reported results were planned to be shared with other researchers. The shared data were planned to include baseline characteristics, stone characteristics, intraoperative details, stone-free outcome on non-contrast computed tomography at four weeks, and postoperative outcomes including complications, pain scores, urine output in the first 24 hours, and need for auxiliary treatment. A data dictionary was planned to be provided.
• IPD Sharing Time Frame: The data were planned to become available after completion of the study and acceptance of the thesis or publication of the primary results, and were planned to remain available for five years.
• IPD Sharing Access Criteria: Access was planned to be provided to qualified researchers upon reasonable request, after review of a brief proposal and analysis plan, and after execution of a data use agreement. Data were planned to be shared in a secure electronic format with de-identification applied.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No