A novel protocol for the characterization of ureteral stent echogenicity

Decreasing radiation exposure in renal colic management involves revisiting diagnostic, intraoperative, and postoperative practices. One approach is a shift in procedural standards from intraoperative fluoroscopy to ultrasonography. Despite the increased implementation of ultrasound in urology, the ultrasound visibility or echogenicity of various stents is not well-studied. Silicone stents, traditionally considered less radiopaque, pose challenges during placement under fluoroscopy due to their reduced visibility. However, a shift to ultrasound-based guidance can levels the playing field, as silicone stents demonstrate comparable echogenicity to stents made from other materials. This study aims to evaluate and quantify the echogenicity of different ureteral stents on the market, with a focus on silicone stents, which traditionally have been considered less radiopaque yet potentially advantageous for less patient discomfort.

We conducted a simulation study using five different brands of ureteral stents in an ex-vivo porcine bladder model. We measured the mean grey intensity to quantify echogenicity of each stent. After comparing the echogenicity of individual stents, we grouped stents based on materials and diameters and performed T-tests.

We established that ureteral stents can demonstrate good visibility inside porcine bladder under ultrasound. Upon further investigation, we found that diameter is the most important variable in determining the measured echogenicity of ureteral stents. 8 Fr ureteral stents have higher measured echogenicity than the Sensor wire and 6 Fr stents. Stent materials also play a role in the measured echogenicity of ureteral stents. With the same diameter, silicone is measurably more echogenic than polyurethane.

This study describes a novel quantitative assessment of ureteral stent echogenicity, which can guide the development of novel echogenic stents and provide a benchmark for existing stents. In addition, it suggests that ultrasonography may facilitate the placement of silicone stents, which historically have been more difficult to visualize with fluoroscopy.