Stone Cone: a device that prevents ureteral stone migration during intracorporeal lithotripsy

Proximal migration of stone fragments during ureteroscopic lithotripsy is a common problem influenced by pressure of irrigation solution, type of energy for lithotripsy, site and degree of fixation of the stone to the ureteral wall, and degree of proximal ureteral dilation. The Stone Cone (Boston Scientific & Spencer) is a device that helps to prevent proximal migration of fragments and favours a safe extraction during ureteroscopic lithotripsy. The Stone Cone is an helical device made of stainless steel and nitinol alloy, which consists of an internal guide wire and a sheath-like radiopaque catheter with a 3 Fr. calibre. Once the cone is placed above the stone it is maintained in that position during lithotripsy to avoid fragment migration. The external catheter is used to coil and unroll the cone, and allows access to place the cone above the stone. We describe two cases of urinary calculi in the left lumbar ureter treated by ureteroscopy and intracorporeal lithotripsy with holmium YAG laser using the Stone Cone to avoid migration of fragments. One month after surgery no lithiasic fragments were observed in the imaging tests. The Stone Cone decreases the need to perform repeated ureteral instrumentations, and is also a safer and simpler method for the extraction of stone fragments. The use of Stone Cone seems to have more advantages than Dormia's basket during ureteroscopic lithotripsy in terms of lower incidence of residual fragments and reoperation rate.