A Resectoscope for Robot-Assisted Transurethral Surgery1

Abstract

During transurethral resection of bladder tumor (TURBT), nonmuscle invasive bladder tumors are excised using an electrocautery wire loop or a laser fiber. The device providing transurethral access for this procedure is a resectoscope. It consists of an endoscope lens to visualize the surgery site and a working element that extends/retracts the cautery loop through an inner/outer sheath.Although TURBT is the gold standard for nonmuscle invasive bladder cancer, there remain several complications, such as bladder wall perforation, irrigant absorption (due to perforation), bleeding, and damage to ureteric orifices. These issues are generally attributed to tool and visualization limitations hindering performance [1]. Surgeons currently violate oncologic principles by removing tumors piece meal, thereby potentially contributing to tumor recurrence. There is an increasing interest in en-block resection to improve outcomes.Robotic assistance can improve bladder cancer diagnosis or treatment by offering more dexterity and workspace coverage and by supporting the deployment of novel instrumentation and imaging technologies. Most robotic assistance systems have been targeted for prostate resection or surveillance. Among the few transurethral robotic systems for bladder application, Yoon et al. reported an automated shape-memory alloy actuated mechanism for bladder cancer detection or surveillance of the bladder [2]. Using this mechanism to steer a scanning fiber endoscope, Soper et al. proposed algorithms to stitch endoscopic images of bladder offline for postoperative review [3].Goldman et al. developed a proof-of-concept telerobotic system for TURBT [4]. A multibackbone continuum robot with three working channels to pass a surgical tool, a fiberscope, and a laser fiber was deployed through an external sheath of a resectoscope in an ex vivo bovine bladder and presented successful dexterous maneuvers in reaching all the bladder zones and performing laser ablation [5]. The design was meant as a proof-of-concept for validating intravesicular dexterity but lacked critical functions for eventual clinical deployment. These missing functions are incorporated in the design presented in this paper. First, the new design adds a custom resectoscope that can be deployed transurethrally similar to a conventional resectoscope. This resectoscope would guide the continuum robot into the bladder cavity while supporting functions of visualization and irrigation. Finally, the design supports a controllable intravesicular visualization in addition to the visualization offered through the steerable robot as described in Ref. [4]. These requirements demand a new design for a robot-compatible resectoscope.We present the mechanical design of a custom resectoscope prototype that was fabricated in-house. This resectoscope has a stem at its distal section that provides working channels for a flexible tool/robot, visualization module, and irrigation. A flexible robot/tool and an endoscope can be inserted through two working channels. The resectoscope can be readily integrated into a robotic platform by sliding it onto a guide rail.Figure 1 presents a prototype of the robot-integrable resectoscope. It is approximately 18.2 in. long, 5.1 in. wide, and weighs about 980 g (without visualization equipment). The design includes a stem (1) that mainly constitutes a custom central stem housed and sealed within an external sheath (see Fig. 2), a sealed adaptor (2) which enables insertion of a visualization module and a flexible robot/tool, a 26Fr endoscope (MEDIT, Inc., Winnipeg, Canada) along with its portable light source for visualization (3), a CCD camera (KARL STORZ, Tuttlingen, Germany) (4) that couples with the endoscope through a C-clamp connection for displaying endoscopic view on a monitor, a fully rotatable endoscope guidance unit (5) to allow quick attachment and 360 deg rotation of the endoscope, an array of valves (6) for enabling controlled irrigation and se