<b>Background and Purpose:</b> Drainage of obstructed kidney due to extrinsic ureteral obstruction (EUO), required to prevent renal damage, is often achieved using double-J ureteral stents. But these stents fail frequently, and there is considerable debate regarding what stent size, type and configuration offer the best option for sustained drainage. Here, we examine the impact of stent diameter and choice of single/tandem configuration, subject to EUO and various degrees of stent occlusion, on stent failure. <b><i>Methods:</i></b> Computational fluid dynamics (CFD) simulations and an in vitro ureter-stent experiment enabled quantification of flow behavior in stented ureters subject to EUO and stent occlusions. Various single and tandem stents under EUO were considered. In each simulation and experiment, changes in renal pressure were monitored for different degrees of stent lumen occlusion, and onset of stent failure as well as simulated distributions of fluid flow between stent and ureter lumina were determined. <b><i>Results:</i></b> For an encircling EUO that completely obstructs the ureter lumen, with or without partial stent occlusion, the choice of stent size/configuration has little effect on renal pressure. The pressure increases significantly for ~90% stent lumen occlusion, with failure at >95% occlusion, independent of stent diameter or a tandem configuration, and with little influence of occlusion length along the stent. <b><i>Conclusions:</i></b> Stent failure rate is independent of stent diameter or single/tandem configuration, for the same percentage of stent lumen occlusion, in this model. Stent failure incidence may decrease for larger diameter stents and tandem configurations, because of the larger luminal area.

中文翻译：

---

单一支架尺寸和串联支架经受外源性输尿管梗阻和支架闭塞对支架失效的影响

<b>背景和目的：</b> 外源性输尿管梗阻 (EUO) 引起的梗阻肾脏引流是防止肾损伤所必需的，通常使用双 J 输尿管支架来实现。但是这些支架经常失效，并且对于什么支架尺寸、类型和配置提供持续引流的最佳选择存在相当大的争论。在这里，我们研究了支架直径和单/串联配置的选择，受 EUO 和不同程度的支架闭塞，对支架失效的影响。<b><i>方法：</i></b> 计算流体动力学 (CFD) 模拟和体外输尿管支架实验能够量化受 EUO 和支架闭塞影响的支架输尿管的流动行为。考虑了 EUO 下的各种单支架和串联支架。在每次模拟和实验中，监测不同程度的支架管腔闭塞的肾压力变化，确定支架失效的发生以及支架和输尿管腔之间的流体流动模拟分布。<b><i>结果：</i></b>对于完全阻塞输尿管腔的环绕式 EUO，无论是否有部分支架闭塞，支架尺寸/配置的选择对肾压影响不大。对于约 90% 的支架管腔闭塞，压力显着增加，在 >95% 的闭塞时失败，与支架直径或串联配置无关，并且沿支架的闭塞长度几乎没有影响。<b><i>结论：</i></b> 支架失败率与支架直径或单/串联配置无关，对于相同百分比的支架管腔闭塞，在这个模型中。由于较大的管腔面积，较大直径的支架和串联配置的支架失效发生率可能会降低。