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NCT Number: NCT07835113

Tissue Sensor for Semirigid Thulium Fiber Laser Ureterolithotripsy

Tissue Sensor (TS) is a technology designed to automatically deactivate laser emission when contact between the laser fiber and tissue is detected. It is hypothesized that the use of TS during contact laser ureterolithotripsy may reduce unintended laser exposure of the ureteral mucosa, thereby decreasing the risk of immediate thermal injury to the ureteral wall and subsequent scar-related narrowing.

To reduce the influence of baseline risk factors for stricture, the study will enroll a homogeneous population of patients without urinary tract anomalies, previous surgery on the study ureter, or impacted stones. The procedure will be performed according to a standardized protocol using a semirigid ureteroscope, a thulium fiber laser, and predefined technical restrictions. The study is limited to patients with stones in the mid or distal ureter. This approach is intended to minimize the likelihood of stone retropulsion into the kidney, standardize the surgical technique, reduce the need for conversion to flexible ureteroscopy, and maximize comparability between the study groups.

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Key information

Conditions

Nephrolithiasis Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Kidney Diseases Male Urogenital Diseases Urogenital Diseases Urolithiasis Urologic Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

• Age 18 years or older.

A single stone in the mid or distal ureter.
Maximum stone diameter of 15 mm or less on preoperative CT.
An indication for elective semirigid laser ureterolithotripsy.
Feasibility of performing the procedure with a semirigid ureteroscope.
No active urinary tract infection at the time of the intervention.
Ability to undergo CT follow-up and complete 12 months of follow-up.
Signed written informed consent.

Exclusion criteria

• Age 18 years or older.

A single stone in the mid or distal ureter.
Maximum stone diameter of 15 mm or less on preoperative CT.
An indication for elective semirigid laser ureterolithotripsy.
Feasibility of performing the procedure with a semirigid ureteroscope.
No active urinary tract infection at the time of the intervention.
Ability to undergo CT follow-up and complete 12 months of follow-up.
Signed written informed consent.

Treatment and study plan

Semirigid TFL ureterolithotripsy with Tissue Sensor activated.

Procedure

Semirigid TFL ureterolithotripsy will be performed with Tissue Sensor activated. All automatic system trigger events will be recorded by the laser system or in the study case report form and, whenever possible, synchronized with the procedure video recording

Semirigid TFL ureterolithotripsy with Tissue Sensor deactivated.

Procedure

Semirigid TFL ureterolithotripsy will be performed with Tissue Sensor deactivated. Visually confirmed contacts between the activated laser fiber and the ureteral mucosa will be recorded from the procedure video.

Primary outcomes

Incidence of intraoperative laser-induced injury to the ureteral mucosa

Time frame: intraoperative

Incidence of intraoperative laser-induced injury to the ureteral mucosa, defined as any visible injury compatible with exposure to an activated laser fiber, as determined by independent blinded video assessment.

Secondary outcomes

Incidence of postoperative ureteral stricture

Time frame: 12 months.
Incidence of postoperative ureteral stricture detected during the 12 months after the intervention.
- Stone-free rate on low-dose non-contrast CT at 1 month.
- Incidence and total number of Tissue Sensor trigger events in the TS group.
- Incidence and total number of visually confirmed contacts between an activated laser fiber and the mucosa in the control group.
- Number of trigger events or contacts per minute of laser activation.
- Severity of mucosal injury according to the standardized scale.
- Total operative time.
- Lithotripsy time.
- Cumulative laser activation time.
- Migration of the stone or fragments into the kidney.
- Need for conversion to flexible ureteroscopy or repeat intervention.
- Type and duration of postoperative drainage.
- Postoperative complications according to the Clavien-Dindo classification.
- New or progressive hydronephrosis during follow-up.

Study contacts

Contact information is provided by the study sponsor or research team.

Nikita Astakhov

CONTACT

[email protected]

+8 (968) 490-46-72

Vigen Malkhasyan, Doctor of Medical Sciences

CONTACT

[email protected]

+79096441688

Sponsors and collaborators

Lead sponsor

Botkin Hospital

Other

Registry information

Official study title

Tissue Sensor to Reduce Laser-Induced Ureteral Injury During Semirigid Thulium Fiber Laser Ureterolithotripsy: The TISSUE Multicenter Randomized Controlled Trial

Acronym: Tissue Sensor

Important dates

Study start: 2026
Primary completion: 2028
Study completion: 2028
First posted: Sep 22, 2026
Registry last updated: Sep 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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