RETROPERITONEAL LAPAROSCOPIC TECHNIQUE IN TREATMENT OF COMPLEX RENAL STONES: 104 CASES

INTRODUCTION AND OBJECTIVES: We compared the flow characteristics of novel three-dimensionally (3D) printed ureteral stents to three conventional double-pigtail stents in an ex vivo porcine model. METHODS: In 5 ex vivo porcine urinary systems with kidneys and ureters intact we deployed a 5Fr occlusion catheter in an interpolar calyx. We tested each system with antegrade irrigation with 0.9% saline at a pressure of 35 cmH2O before and after stent deployment. We evaluated three standard stents (6Fr Universa Soft, 7Fr Percuflex , 7/10Fr Applied Endopyelotomy) and compared them to a 9Fr 3D printed prototype stent. For each stent, we measured the total, extra-luminal, and intra-luminal flow rates. RESULTS: The mean total flow rates for 3D printed stents were significantly higher than the 6Fr, 7Fr, and 7/10Fr stents (p<0.001, p1⁄40.003, and p<0.001 respectively). The mean extra-luminal flow rates for the 3D stents were similar to 7Fr stents, but significantly lower than 6Fr stents (p<0.001) and higher than 7/10Fr stents (p<0.001). The mean intra-luminal flow rates for the 3D printed stents were significantly higher than the 6Fr, 7Fr, and 7/10Fr stents (p<0.001, p1⁄40.004, and p<0.001 respectively). CONCLUSIONS: In this pilot study, 3D printed stents manifested a mean total flow rates comparable to the flow rates of contemporary stents. Continued advances in technology and material may permit functionally feasible 3D printed ureteral stents.