Predicting the Success of Flexible Ureterorenoscopy for Kidney and Upper Ureter Stones

August 4, 2026 updated by: Abdelrahman Sayed Abdelrehim Abdelaziz, Assiut University

Validation of a Nomogram for Prediction of Success of Flexible Ureterorenoscopy for Treatment of Renal and Upper Ureteric Stones

This observational study aims to test how well a specific medical scoring tool, called a nomogram, can predict the success of a common minimally invasive surgery for kidney stones. The surgery being studied is flexible ureterorenoscopy (fURS), which is widely used to treat stones in the kidney and the upper part of the ureter. In this study, procedural success is defined as a patient being completely stone-free after their surgery.

While fURS is highly effective, the chances of completely clearing all stones can vary from person to person based on individual factors like stone size, stone volume, and anatomical characteristics. Researchers want to determine if this nomogram can accurately estimate a patient's personalized chance of achieving a stone-free outcome before the intervention takes place.

Participants in this study will be adult patients who are already scheduled to undergo fURS as part of their standard medical care. Because this is an observational study, there are no experimental treatments, participants will receive their normal surgical care.

During the study, the research team will collect standard clinical information, including:

  • Preoperative data such as age, body mass index (BMI), blood tests, and CT scan results.
  • Operative details during the surgery, such as the time it takes, the experience level of the surgeon, and the laser settings used to break up the stones.
  • Postoperative outcomes, specifically reviewing follow-up imaging to check for the presence and size of any remaining stone fragments.

By comparing the nomogram's preoperative predictions to the patients' actual surgical results, the researchers hope to validate the tool's accuracy. Confirming the reliability of this tool could help doctors better plan individualized treatments, avoid unnecessary procedures, and improve how they counsel future patients regarding their expected surgical outcomes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

Urolithiasis remains one of the most common urological diseases globally, characterized by increasing incidence and recurrence rates. While flexible ureterorenoscopy (fURS) has become a preferred minimally invasive treatment for renal and upper ureteric stones due to its high efficacy and low morbidity, the stone-free rate (SFR) varies significantly among patients. To optimize patient counseling and treatment selection, predictive nomograms have emerged as practical tools that integrate multiple clinical and radiological variables into a single, individualized probability estimate for achieving stone clearance.

However, external validation is a critical prerequisite before adopting any predictive model into routine clinical practice. A nomogram developed in one population may exhibit different predictive accuracy in another due to variations in patient characteristics, stone burden, and local healthcare settings. Currently, there is limited evidence regarding the performance of published fURS predictive models in Middle Eastern and Egyptian populations. This study addresses this gap by conducting an independent external validation of a published nomogram at Assiut University Hospitals.

The study involves a comprehensive, multi-phase data collection process for all enrolled participants:

  • Preoperative Assessment: Patients will undergo clinical, laboratory, and radiological evaluations. Baseline demographic data (age, sex, body mass index) and serum creatinine levels will be recorded. Stone characteristics will be evaluated using computed tomography (CT) to document stone size, volume, number, location, laterality, and the presence of hydronephrosis. CT findings specifically required to calculate the nomogram score will be systematically extracted.
  • Intraoperative Parameters: During the fURS procedure, the surgical team will prospectively record the total operative time, utilization of a ureteral access sheath, specific laser lithotripsy settings utilized for fragmentation, the operating surgeon's experience level, and any intraoperative complications encountered.
  • Postoperative Evaluation: Following the surgery, researchers will document the duration of the hospital stay, any postoperative complications, and the potential need for auxiliary procedures (such as repeat ureteroscopy, shock wave lithotripsy, or percutaneous interventions for residual stone burden).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
70

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

N/A

Sampling Method

Non-Probability Sample

Study Population

The study population consists of adult patients, aged 18 years and older, of both sexes who present with renal or upper ureteric stones. These patients must be scheduled to undergo flexible ureterorenoscopy (fURS) as part of their standard clinical management. Participants will be drawn from the patient population receiving routine care at the Urology Department of Assiut University Hospitals.

Description

Inclusion Criteria:

  • Adult patients (≥18 years).
  • Both sexes.
  • Patients with renal stones.
  • Patients with upper ureteric stones.
  • Patients scheduled for flexible ureterorenoscopy.
  • Patients willing to provide informed consent.

Exclusion Criteria:

  • Congenital urinary tract anomalies.
  • Active urinary tract infection.
  • Pregnancy.
  • Patients with incomplete clinical or radiological data.
  • Patients lost to follow-up.

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

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Patients Undergoing Flexible Ureterorenoscopy (fURS)
This cohort consists of adult patients (18 years and older) of both sexes diagnosed with renal or upper ureteric stones who are scheduled to undergo flexible ureterorenoscopy (fURS) as part of their routine clinical management. Preoperative characteristics, intraoperative parameters, and postoperative outcomes will be prospectively recorded to validate a predictive nomogram for determining stone-free status.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Stone-Free Rate
Time Frame: 4 weeks post-procedure
Treatment outcome determined through postoperative imaging to document the presence and size of any residual stone fragments.
4 weeks post-procedure

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Predictive Accuracy of the Nomogram
Time Frame: 4 weeks post-procedure
The discrimination ability of the nomogram to accurately predict stone-free status after the procedure, evaluated using the Area Under the Receiver Operating Characteristic (AUC-ROC) curve.
4 weeks post-procedure

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Assiut 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 4, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 4, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 7, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 7, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 4, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • fURS Success Nomogram Validity

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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