Impact of Surgical Position on Stone-Free Rates in Retrograde Intrarenal Surgery (POS-RIRS-RCT)

August 14, 2025 updated by: Murat Gulsen, Ondokuz Mayıs University

Does the Positioning in Retrograde Intrarenal Surgery Affect Stone-Free Rates? A Prospective Randomized Controlled Trial

The goal of this clinical trial is to determine whether the surgical position during retrograde intrarenal surgery (RIRS) affects stone-free rates in adults with kidney stones. The main questions it aims to answer are:

  • Does the modified lithotomy position result in a higher stone-free rate compared to the standard lithotomy position?
  • Are there differences in complication rates between the two surgical positions?

Researchers will compare patients undergoing RIRS in the standard lithotomy position to those in the modified lithotomy position (30-degree Trendelenburg with elevated surgical side) to assess its impact on stone clearance and surgical outcomes.

Participants will:

  • Be randomly assigned to one of two surgical positions
  • Undergo RIRS with standard surgical procedures
  • Have follow-up imaging to assess stone clearance after surgery

This study aims to improve surgical techniques and patient outcomes in kidney stone treatment.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

128

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Turkey
      • Samsun, Turkey
        • Recruiting
        • Ondokuz Mayıs University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Presence of single or multiple kidney stones, with the largest stone ≤2 cm
  • Age ≥18 years
  • Provided written informed consent to participate in the study
  • Indicated for retrograde intrarenal surgery (RIRS) as a treatment approach

Exclusion Criteria:

  • Severe cardiovascular disease (e.g., heart failure)
  • Congenital kidney anomalies (e.g., horseshoe kidney, ectopic kidney)
  • Concurrent ureteral stones
  • Pregnancy or planning pregnancy
  • History of previous kidney surgery on the same side
  • Active urinary tract infection (UTI)
  • Coagulopathy or use of anticoagulant therapy that cannot be stopped before surgery

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
No Intervention: Standard lithotomy position
In this arm we will use standard lithotomy position as control group.
Active Comparator: T-Tilt Lithotomy Position
Procedure: The T-Tilt position

The T-Tilt position is a modified lithotomy position used during retrograde intrarenal surgery (RIRS). In this position:

The patient is placed in a 30-degree Trendelenburg position, meaning the head is slightly lower than the feet.

The surgical side is elevated at a 30-degree angle to improve access to the kidney.

This modified positioning is designed to enhance stone clearance, particularly by facilitating the movement of stone fragments away from the lower kidney calyces, where residual stones often remain. Researchers will compare this position to the standard lithotomy position to determine its impact on stone-free rates and surgical outcomes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Stone-Free Rate After Retrograde Intrarenal Surgery
Time Frame: 6 weeks post-surgery
The percentage of participants with no residual kidney stones (≤4 mm fragments) on non-contrast computed tomography (CT) at 6 weeks postoperatively.
6 weeks post-surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Complication Rate
Time Frame: Within 30 days post-surgery
he percentage of participants experiencing any postoperative complications, classified according to the Clavien-Dindo grading system.
Within 30 days post-surgery

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Rehospitalization Rate
Time Frame: Within 30 days post-surgery
The percentage of participants requiring hospital readmission due to complications related to the surgical procedure
Within 30 days post-surgery
Total Laser Energy Used
Time Frame: Intraoperative
The total Holmium:YAG laser energy (Joules) applied during stone fragmentation
Intraoperative

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ondokuz Mayıs University

Investigators

  • Principal Investigator: Murat Gulsen, Ondokuz Mayıs University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2025

Primary Completion (Estimated)

December 1, 2025

Study Completion (Estimated)

June 1, 2026

Study Registration Dates

First Submitted

January 30, 2025

First Submitted That Met QC Criteria

January 30, 2025

First Posted (Actual)

February 5, 2025

Study Record Updates

Last Update Posted (Estimated)

August 15, 2025

Last Update Submitted That Met QC Criteria

August 14, 2025

Last Verified

August 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • B.30.2.ODM.0.20.08/603-670

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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