Preclinical Evaluation of a Newly Designed Ureteral Stent and Magnetic Retrieval Catheter for Minimally Invasive Stent Removal

ObjectiveTo develop a simple minimally invasive method for ureteral stent removal that does not require cystoscopy or fluoroscopic guidance.Materials and MethodsWe developed a novel ureteral stent comprising the main body of a stent and an iron oxide–coated net that was woven of processed polyester sutures. The ureteral stent was retrieved by a magnetic retrieval catheter with small hooks on the neck surface. Detailed analysis of the necessary mechanical and magnetic properties was performed, and we conducted retrieval tests of the ureteral stent from a specially designed urinary system model.ResultsThe breaking strength and Young modulus of the processed polyester sutures were 10.12 ± 0.30 N and 9143 ± 7 N/tex, respectively. Thermogravimetric tests showed that the iron (III) oxide powders on the processed sutures accounted for 23% of the total weight. The magnetization value of the magnetic retrieval catheter was 578 emu/g. The dissolution times of polyvinyl alcohol wrapped the net in saline or urine were 24.2 ± 2.0 and 23.6 ± 3.1 hours, respectively. All stents in both the experimental and the control groups were successfully removed from the specially designed urinary model. However, the retrieval time in the experimental group was significantly shorter than that in the control group (38.6 ± 12.6 vs 59 ± 15.7 seconds; P <.05).ConclusionUreteral stent removal using a magnetic retrieval catheter with small capture devices is considered feasible. This technique is easy to learn and should be considered as suitable for use on an outpatient basis.