Immediate intraoperative detrusor muscle status at primary transurethral resection of bladder tumour: a prospective, blinded, paired cohort, feasibility study using fluorescence confocal microscopy (
IB1
Martin J. Connor, Archana Gopalakrishnan, Nikhil Mayor, Eva Bolton, Sami Hamid, Sai Kalpitha Reddy, Tayla Perreau, Eslam Maher, Alexander Light, Samuel Morris, Jiten Jaipura, Mariana Bertoncelli Tanaka, Norma Gibbons, Archie Hughes‐Hallett, Hashim U. Ahmed, Rakesh Heer, Andrew Smith, David Hrouda, Anna Silvanto, Mona El‐Bahrawy, Mathias Winkler Objectives
To evaluate ex vivo fluorescence confocal microscopy (FCM) for immediate detrusor muscle (DM) assessment during primary transurethral resection of bladder tumour (TURBT).
Patients and Methods
This prospective, blinded, paired‐cohort feasibility study enrolled consecutive patients undergoing primary TURBT for suspected non‐muscle‐invasive bladder cancer between September 2024 and September 2025 (IB1‐LaserComplete study; International Standard Randomised Controlled Trial Number Register [ISRCTN]16114765). Ex vivo FCM generates immediate high‐resolution digital images of fresh tissue, enabling immediate DM assessment. Intraoperative ex vivo FCM imaging of en face tumour base specimens was performed using the Histolog® scanner (SamanTree Medical SA, Lausanne, Switzerland). DM status was reported by a blinded uro‐pathologist and urologist. Formalin‐fixed histopathology served as the reference standard. The primary outcome was technical feasibility, defined as acquisition of an interpretable FCM image. Secondary outcomes included exploratory diagnostic performance, inter‐observer agreement and time to confirmation of DM status.
Results
A total of 34 patients were recruited and 30 had evaluable paired specimens. DM was absent in 13% (four of 30). FCM was sufficient for determining DM status in all patients (100%; 30 of 30). Sensitivity, specificity, positive predictive value, negative predictive value (NPV) were 42% (95% confidence interval [CI] 26–61%), 100% (95% CI 51–100%), 100% (95% CI 74–100%), and 21% (95% CI 9–43%), respectively. Inter‐observer agreement between the uro‐pathologist and urologist was high at 83% (κ = 0.72, 95% CI 0.47–0.97). The median (interquartile range) time to confirm DM status was 5.4 (4.95–5.39) min vs 11 (7–13.8) days using standard histopathology.
Conclusion
Fluorescence confocal microscopy is feasible for rapid intraoperative imaging of TURBT specimens and demonstrates excellent specificity for detection of DM. However, its low sensitivity and NPV preclude use as a stand‐alone tool to exclude DM intraoperatively. Based on these findings, FCM should not guide intraoperative decision making outside research settings.