DISS vs FANS in Suction-Assisted RIRS for Medium-Sized Renal Stones

April 1, 2026 updated by: Ahmed Samy Abd Elmawgod Ali Marey, Ain Shams University

The Impact of Suction-Assisted RIRS (DISS Versus FANS) on Postoperative Infection Rate and Stone-Free Rate After Treatment of Medium Sized Renal Stones

Kidney stones are a common health problem and may recur frequently, which can affect quality of life and kidney function. Retrograde intrarenal surgery (RIRS) is a minimally invasive treatment used for renal stones, but treatment of medium-sized stones may be associated with longer operative time, impaired visibility during surgery, residual stone fragments, and postoperative infectious complications caused by increased intrarenal pressure.

Suction-assisted retrograde intrarenal surgery (RIRS) techniques have been developed to improve surgical efficiency and safety by facilitating continuous removal of stone fragments and helping control intrarenal pressure. Two commonly used suction-assisted approaches are direct in-scope suction (DISS) and flexible and navigable suction ureteric access sheath (FANS). However, there is limited prospective randomized evidence directly comparing these two techniques.

This randomized prospective clinical study aims to compare direct in-scope suction (DISS) versus flexible and navigable suction ureteric access sheath (FANS) in adult patients with medium-sized renal stones measuring 2 to 3 cm who are undergoing retrograde intrarenal surgery (RIRS). Participants will be randomly assigned to one of the two suction-assisted techniques. The study will evaluate whether flexible and navigable suction ureteric access sheath (FANS) provides better outcomes than direct in-scope suction (DISS) in terms of stone-free rate and postoperative infection rate.

The primary outcome is stone-free status assessed by postoperative imaging. Secondary outcomes include operative time, intraoperative visibility, and postoperative complications, particularly infection and urosepsis. The study hypothesis is that suction-assisted retrograde intrarenal surgery (RIRS) using the flexible and navigable suction ureteric access sheath (FANS) technique will result in a higher stone-free rate and a lower postoperative infection rate compared with direct in-scope suction (DISS) in the management of medium-sized renal stones.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

126

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

  • Egypt
      • Cairo, Egypt, 11511
        • Ain Shams University Hospitals

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

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults aged 18 to 60 years
  • Radiologically confirmed renal stones measuring 2 to 3 centimeters
  • Eligible for retrograde intrarenal surgery
  • Normal renal function as evidenced by normal serum creatinine
  • Able and willing to provide written informed consent

Exclusion Criteria:

  • Pregnancy or lactation
  • Active urinary tract infection at the time of enrollment
  • Bleeding disorders or coagulopathies that contraindicate surgical intervention
  • Anatomical malformations affecting the urinary tract
  • Solitary kidney
  • Inability or unwillingness to provide informed consent

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: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: In-Scope Suction Group
Participants assigned to this arm will undergo suction-assisted retrograde intrarenal surgery using direct in-scope suction. A single-use flexible ureteroscope with suction function will be used, and direct suction will be applied through the working channel during laser lithotripsy. Negative pressure will be maintained between 2 and 7 kilopascals and adjusted intraoperatively according to visibility and fragment evacuation. Laser lithotripsy will be performed using a holmium:yttrium-aluminum-garnet laser with dusting and popcorn techniques, followed by placement of a 6 French double-J ureteral stent.
Procedure: Direct In-Scope Suction
Direct suction is applied through the working channel of the flexible ureteroscope during retrograde intrarenal surgery to facilitate evacuation of stone fragments and improve intraoperative visibility during laser lithotripsy.
Other Names:
  • DISS
Experimental: Flexible and Navigable Suction Ureteric Access Sheath Group
Participants assigned to this arm will undergo suction-assisted retrograde intrarenal surgery using a flexible and navigable suction ureteric access sheath. The sheath will be inserted under guidewire guidance and connected to a vacuum device. Negative pressure will be maintained between 2 and 7 kilopascals and adjusted intraoperatively according to visibility and fragment evacuation. Laser lithotripsy will be performed using a holmium:yttrium-aluminum-garnet laser with dusting and popcorn techniques. Suction will be applied intermittently through the sheath to facilitate fragment evacuation, followed by placement of a 6 French double-J ureteral stent.
Procedure: Flexible and Navigable Suction Ureteric Access Sheath
A flexible and navigable suction ureteric access sheath is used during retrograde intrarenal surgery to provide suction-assisted evacuation of stone fragments, improve visibility, and support intrarenal pressure control during laser lithotripsy.
Other Names:
  • FANS

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Stone-Free Rate
Time Frame: At 1 month after surgery
Stone-free status will be assessed by postoperative imaging using kidney, ureter, and bladder radiography and non-contrast computed tomography. Clinically insignificant residual fragments will be defined as residual fragments measuring 2 to 3 millimeters or less.
At 1 month after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Infection Rate
Time Frame: Within 1 month after surgery
The proportion of participants who develop any postoperative infectious complications.
Within 1 month after surgery
Operative Time
Time Frame: During surgery (Intraoperatively)
Operative time measured in minutes from ureteroscope insertion to successful placement of the double-J ureteral stent.
During surgery (Intraoperatively)
Intraoperative Visibility Score
Time Frame: During surgery (Intraoperatively)
Intraoperative visibility will be graded by the operating surgeon using a 3-point scale: grade 0 for poor visibility, grade 1 for moderate visibility, and grade 2 for good visibility.
During surgery (Intraoperatively)
Postoperative Complication Rate
Time Frame: Within 1 month after surgery
The proportion of participants with postoperative complications classified according to the Clavien-Dindo classification system.
Within 1 month after surgery

Collaborators and Investigators

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

Sponsor

Ain Shams University

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 (Estimated)

April 30, 2026

Primary Completion (Estimated)

April 30, 2027

Study Completion (Estimated)

April 30, 2027

Study Registration Dates

First Submitted

April 1, 2026

First Submitted That Met QC Criteria

April 1, 2026

First Posted (Actual)

April 8, 2026

Study Record Updates

Last Update Posted (Actual)

April 8, 2026

Last Update Submitted That Met QC Criteria

April 1, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FMASU MS 142/2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data underlying the results reported in this study will be made available, including demographic data, baseline characteristics, intervention allocation, outcome measures, and adverse event data.

IPD Sharing Time Frame

Data will become available beginning 6 months after publication of the main study results and will remain available for 5 years.

IPD Sharing Access Criteria

Data will be available to qualified researchers who provide a methodologically sound research proposal. Requests should be directed to the corresponding investigator. Access will be granted after review and approval of the proposal and execution of a data access agreement, with use limited to the purposes described in the approved proposal.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • 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

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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