Comparison of flexible grasping forceps and stone basket for removal of retracted ureteral stents

Background: Ureteral-stent dislocation can occur either during positioning or postoperatively. Grasping the distal end of the stent and removing it depends on the angulation between the extraction device and the stent, the size and length of the instrument, and the force of the branches and resistance of the dislocated stent. Patients and Methods: Six cases of challenging stent removal are presented, and details of the surgical technique are described. By in-vitro testing, we investigated the deflection of flexible cystoscopes and ureteroscopes using forceps or a four-wire stone basket, the ability to grasp a stent depending on the angle between the stent axis and the extraction device, and the force that can be applied on the stent with the different devices. Results: In all cases, it was possible to extract the stent with a stone basket. In an in-vitro setting, maximum extraction forces, measured with a macro scale, were 1.3 kg (cystoscopic forceps) and 0.4 kg (ureteroscopic forceps) until the forceps slipped off the stent. In the same setting, a rupture of the wires of the 1.9F stone basket occurred at 0.8 kg, whereas with a 2AF basket, a force of 1.9 kg led to rupture of the stent, leaving the basket intact. Conclusions: Using a stone basket instead of grasping forceps in difficult cases of dislocated stents opens new possibilities for their cystoscopic and ureteroscopic removal. Because the superiority of the basket is counterbalanced by its higher costs, we suggest the basket extraction method only in difficult cases.