REtrieval of Transurethrally Resected Intact En-bloc Vesical Tumors Using a Retrieval Device for Bladder Tumors

Here is the Detailed Description for ClinicalTrials.gov:

Study Design The RETRIEVE-BT Trial is a prospective, multicenter, single-arm, non-randomized feasibility study conducted at multiple urological centers. No control group or randomization is applied, as the study is designed to characterize the technical performance of the CURTIS device under real-world clinical conditions rather than to test a comparative efficacy hypothesis.

The CURTIS Device CURTIS (Urotech GmbH, Achenmühle, Germany) is a CE-marked medical device specifically developed for transurethral retrieval of intact bladder tumor specimens following en bloc resection. The device consists of a hydrophilic-coated retrieval bag that can be opened and closed via a handpiece, enabling controlled capture and safe transurethral extraction of the resected specimen. It is used within its approved intended purpose as defined by EU MDR 2017/745.

Surgical Procedure All procedures are performed under general or spinal anesthesia. En bloc transurethral resection is carried out using a standard resectoscope with an appropriate electrode (e.g., bipolar hook, J-electrode, or needle electrode). A circumferential incision is made in healthy urothelium approximately 3-5 mm lateral to the visible tumor margin, followed by en bloc dissection at the submucosal or muscularis propria level. Once the specimen is fully detached from the bladder wall, CURTIS-assisted retrieval is attempted according to the manufacturer's instructions for use. If retrieval with CURTIS is unsuccessful, conversion to an alternative extraction method is performed at the surgeon's discretion and documented.

Data Collection and Follow-up Data are collected prospectively via an electronic Case Report Form (eCRF). Intraoperative variables recorded include retrieval success or failure, reason for failure if applicable, total procedure time, and dedicated retrieval time. Resected specimens are processed by the local pathology department according to institutional standards; pathological variables include specimen dimensions, muscularis propria presence, pathological T-stage, histological grade (WHO 2022), and resection margin status. Postoperative complications are documented according to the Clavien-Dindo classification until hospital discharge. No additional study-specific outpatient follow-up visits are required.

Statistical Approach This is a pilot feasibility study; the statistical approach is primarily descriptive. The primary endpoint will be reported as an observed proportion with exact 95% Clopper-Pearson confidence interval. A predefined technical feasibility rate of ≥80% is the threshold indicating clinical utility. Secondary endpoints will be analyzed descriptively. A threshold analysis will be applied to identify the maximum tumor size associated with successful intact retrieval.

Inclusion criteria

• Age ≥18 years at the time of enrollment
• Suspected primary non-muscle invasive bladder cancer (NMIBC; stage pTa or pT1) based on cystoscopic assessment, with no radiological or clinical evidence of muscle-invasive disease
• Solitary or multiple bladder tumors with an estimated largest diameter of ≤50 mm based on flexible or rigid cystoscopic assessment (or cross-sectional imaging if available)
• Clinical indication for elective transurethral resection of the bladder tumor, planned to be performed as en-bloc resection
• Written informed consent obtained prior to any study-related procedure
• Ability to understand the study procedures and willingness to comply with study requirements

Exclusion criteria

• Known or clinically suspected muscle-invasive bladder cancer (MIBC; cT2 or higher) based on cystoscopy or imaging
• Recurrent bladder tumor (prior history of bladder tumor resection within the past 24 months)
• Active untreated urinary tract infection at the time of surgery (requiring postponement and re-evaluation)
• Uncorrectable coagulopathy or anticoagulation that cannot be safely paused perioperatively
• Severe urethral stricture precluding standard resectoscope passage
• Inability to provide written informed consent (e.g., due to cognitive impairment or language barrier without translation support)