Abstract

Introduction: Ureteroscopy is a very common modality used to treat ureteral calculi. Retrograde stone migration during ureteroscopic lithotripsy might be seen in 40-50% of proximal ureteral stones. Stones are pushed often completely back to the kidney or stone fragments might migrate. This migration increases morbidity and the need for additional procedures. Various different equipments and techniques have been developed for preventing stone migration. Lithocatch™, Lithovac™ and Parachute™ are some of these devices. Nevertheless these devices are only 12 Fr in largest diameter which may be too small for dilated ureters and they fill up the most of the space of the ureteroscope working channel. The stone cone™ is a device that goals to prevent proximal calculus migration and allow safe extraction of small calculi during ureteroscopy. The stone cone™ catheter may be used to for these aims during ureteroscopic lithotripsy. In this study, we assessed the clinical use and efficacy of the stone cone™ device in the treatment of proximal ureter stones.

Materials and Methods: Between 2003 and 2004, we used the stone cone™ in 22 patients with proximal ureteral calculi undergoing ureteroscopic lithotipsy. The mean age of patients was 33.6±0.6 years (19 to 59) and mean stone diameter was 9.6±1.4 mm (8-21 mm). Stones were on right side in 13 patients and on left side in 9 patients. Preoperative examinations included plain x-ray film of the kidneys, ureters and bladder, excretory urography and urine culture. All procedures were performed under general anesthesia and all patients were operated on standard lithotomy position. Ureteroscopy was performed with 8.5 Fr semirigid ureteroscope. Pneumatic lithoriptor was used for lithotripsy in all cases. Stone cone™ was introduced through the cystoscope under fluoroscopic control. Stone cone™ was required placement under direct ureteroscopic control in patients with impacted stones.

Results: Stone cone™ was placed successfully in 22 patients. In 14 patients, it was placed via cystoscopy under fluoroscopic guidance, while 8 patients with impacted stones required ureteroscopic placement. Mean operation time was 55±16 minutes (35-80 min). Intracoporeal pneumatic lithotripsy was used in all patients. All stones were fragmented successfully with pneumatic lithotriptor. Ureteral stent was placed to all patients with impacted ureteral stones. Stone fragments, which were entrapped in the ureter by the stone cone™, were extracted safely with common stone baskets. Stone migration was seen in only 1 (4.5%) patient, in which a 3 mm stone fragment migrated to the kidney. No major complication was associated with the use of stone cone™.

Conclusion: In this study, stone cone™ catheter was used in 22 patients with proximal ureteral stone and the efficacy plus the safety of this catheter was evaluated. In our experience, stone cone™ is an effective and useful device that prevents proximal ureteral stone migration and allows safe extraction of fragments during ureteroscopic lithotripsy. We think that failure in trapping fragments smaller than 3 mm, is the main disadvantage of this device. The stone cone™ appears to be a useful addition to the urological armemantarium.