Arrangement of side holes in a double J stent for high urine flow in a stented ureter

A double J stent (DJS) is widely used as an ureteral stent these days. A DJS is composed of a shaft and proximal and distal coils, and it has multiple side holes along the stent axis. The role of side holes must be a supply of detour. Several studies on side holes have been conducted. Various parameters, such as the number of side holes, the distance between adjacent side holes, and the degree of ureteral stenosis, have been evaluated. Studies have shown that increasing the number of side holes increases the overall flow rate, but it has not presented an important role in the absence of ureteral stenosis. In the absence of ureteral stenosis, only a few proximal and distal side holes show a role of detour, and the flow of urine through a stent is negligible. Here, we examine whether urine flow through a stented ureter is maximized by removing side holes in the midshaft and increasing the number of side holes in the proximal and distal segments of the stent shaft. We establish an undulated curved ureter model and compare a stent with only proximal and distal side holes in the shaft with a stent with side holes along the entire shaft in a point of flow rates in the ureter and flow patterns around side holes. The stent with side holes along the entire shaft (16.5 mL/h) shows a higher total flow rate compared with the stent with only proximal and distal side holes in the shaft (12.7 mL/h).