Urethral Resistive Index (URI): A New Parameter for Diagnosing Urethral Obstruction (URI)

March 31, 2026 updated by: Yusuf Gökkurt, Ankara City Hospital Bilkent

Urethral Resistive Index (URI): A New Uroflowmetric Parameter in the Non-Invasive Diagnosis of Urethral Obstruction

This prospective observational study aims to evaluate the diagnostic accuracy of a new, non-invasive uroflowmetry parameter called the Urethral Resistive Index (URI) for detecting urethral stricture in men. Currently, diagnosing urethral stricture often requires invasive procedures like surgery or pressure-flow studies. This research seeks to develop URI as a practical and painless screening tool that could reduce the need for such invasive interventions.

Study Procedures:

A total of 60 male participants (30 with suspected urethral stricture and 30 healthy volunteers) will be enrolled. Participants will undergo two standard, non-invasive uroflowmetry (voiding) tests. The first test is a routine natural voiding session. The second test involves a "forced voiding" (Valsalva maneuver) once the participant feels a sufficient urge to urinate again. The URI is then calculated by comparing the flow rates of these two sessions.

Goals and Benefits: The primary goal is to determine the optimal "cut-off" value of the URI that accurately identifies a surgically proven urethral stricture. By demonstrating URI's effectiveness, the study aims to expedite the diagnostic process and spare patients from unnecessary invasive tests. The procedure involves minimal risk, primarily temporary discomfort or psychological stress during the voiding tests

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This methodological study is designed as a prospective, cross-sectional, and observational diagnostic accuracy study. The primary objective is to evaluate the clinical validity of the Urethral Resistive Index (URI), a novel non-invasive parameter, in the diagnosis of urethral stricture.

Study Population and Groups:

The study will include a total of 60 male participants aged between 18 and 80 years.

Stricture Group (n=30): Patients planned for surgery (urethroplasty or internal urethrotomy) due to suspected urethral stricture, where the presence of the stricture is confirmed intraoperatively.

Control Group (n=30): Healthy male volunteers without lower urinary tract symptoms, matched for age.

Methodology: The study focuses on comparing standard uroflowmetry with "forced" uroflowmetry using the Valsalva maneuver. All clinical and uroflowmetric parameters will be collected at the Ankara Bilkent City Hospital Urology Clinic.

Natural Uroflowmetry: Participants will perform a standard uroflowmetry test. Forced Uroflowmetry: After reaching sufficient bladder fullness again, participants will perform a second test using the Valsalva maneuver (forced voiding).

Calculation: The URI will be calculated using the formula:

URI= Qmax,forced/ Qmax,normal

Statistical Analysis: The diagnostic performance of the URI will be evaluated using Receiver Operating Characteristic (ROC) curve analysis. The Area Under the Curve (AUC) will be calculated, and the optimal cut-off value for determining urethral stricture will be identified with corresponding sensitivity and specificity values. Correlation between URI and clinical symptom scores, such as the International Prostate Symptom Score (IPSS), will also be analyzed.

Study Type

Observational

Enrollment (Estimated)

60

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 (Türkiye)
    • Universiteler
      • Ankara, Universiteler, Turkey (Türkiye), 06800
        • Recruiting
        • Ankara Bilkent City Hospital
        • 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

Yes

Sampling Method

Non-Probability Sample

Study Population

The study population consists of 60 male participants, aged 18 to 80 years, recruited from the Urology Outpatient Clinic at Ankara Bilkent City Hospital. The population is divided into two distinct groups: a Stricture Group (n=30) comprising patients with suspected urethral stricture whose diagnosis is confirmed intraoperatively during scheduled surgery, and a Control Group (n=30) comprising healthy male volunteers with a similar age distribution and no lower urinary tract symptoms. Participants are selected based on their clinical presentation and willingness to undergo a specialized two-stage uroflowmetry protocol.

Description

Inclusion Criteria:

  • Male participants aged between 18 and 80 years.
  • For the Stricture Group: Patients scheduled for surgery (urethroplasty or internal urethrotomy) due to suspected urethral stricture, where the diagnosis is confirmed intraoperatively.
  • For the Control Group: Healthy male volunteers without any lower urinary tract symptoms.
  • Voluntary signing of the Informed Consent Form.

Exclusion Criteria:

  • Voiding volume less than 150 mL.
  • Causes of obstruction other than stricture, such as Benign Prostatic Hyperplasia (BPH).
  • Diagnosis of neurogenic bladder dysfunction or a history of neurological disease affecting bladder function.
  • Presence of severe comorbidities.

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
Intervention / Treatment
Stricture Group
Patients with suspected urethral stricture scheduled for surgery (urethroplasty or internal urethrotomy), with the diagnosis confirmed intraoperatively.
Diagnostic test: Uroflowmetry with URI Calculation
Performing natural and forced (Valsalva) uroflowmetry sessions to calculate the Urethral Resistive Index.
Control Group
Healthy male volunteers in a similar age range as the stricture group, without any lower urinary tract symptoms.
Diagnostic test: Uroflowmetry with URI Calculation
Performing natural and forced (Valsalva) uroflowmetry sessions to calculate the Urethral Resistive Index.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Urethral Resistive Index (URI)
Time Frame: At the time of the uroflowmetry procedure (Baseline)
A novel non-invasive uroflowmetric parameter calculated to assess the resistance of the urethra during voiding. It is derived using the formula: URI=Qmax,natural/Qmax,forced.
At the time of the uroflowmetry procedure (Baseline)

Collaborators and Investigators

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

Sponsor

Ankara City Hospital Bilkent

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)

February 10, 2026

Primary Completion (Estimated)

May 10, 2026

Study Completion (Estimated)

July 10, 2026

Study Registration Dates

First Submitted

February 5, 2026

First Submitted That Met QC Criteria

February 5, 2026

First Posted (Actual)

February 11, 2026

Study Record Updates

Last Update Posted (Actual)

April 6, 2026

Last Update Submitted That Met QC Criteria

March 31, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • TABED 1/2090/2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

To protect participant privacy and maintain data confidentiality according to local institutional regulations

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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