Patients were enrolled in the study if they presented with radiopaque ureteral stones, had an indwelling ureteral stent, and were scheduled for ureteroscopy (URS) or extra-corporeal shock wave lithotripsy (ESWL). The day prior to the scheduled procedure, participating patients would have their indwelling ureteral stents removed via flexible cystoscopy. Overnight, patients were then asked to filter their urine. If patients passed any stones during this time, the patient was discharged and scheduled for follow up a few weeks later. In the case that no stones were passed, patients were admitted to the hospital overnight for observation and again filtered their urine. If stone(s) were passed the patient was discharged and scheduled for a follow up in a few weeks. If the stone burden persisted, patients then underwent their scheduled URS or ESWL. No additional treatment was given to these patients including alpha blockers or other medications. The limitations of this study included the retrospective design and competitively selective inclusion requirements to only patients with a solidary symptomatic radiopaque ureteral stone. Dr. Piet Bosshard reiterated that due to his institution’s strict protocol and regular follow-up appointments, relevant bias was limited. Patient baseline characteristics can be viewed in Table 1, which was taken directly from Dr. Piet Bosshard’s presentation.
In total, data from 216 patients was collected in this study. Overall, 60% (129/216) of patients were able to avoid surgery due to spontaneous stone passage after removal of their ureteral stent, 44% (57/129) of which passed stones within one day of stent removal. Importantly, not a single patient presented with infectious complications after stent removal. Among in situ stone patients (n=142), 28% experienced pain prior to stent removal. After stent removal, 20% (28/142) of these patients were prescribed PO pain medication and 8% (12/142) were prescribed IV pain medication. In these cases, there was 12% and 0% spontaneous stone passage, respectively. Multiple predictive factors were examined in patients who spontaneously passed stones during stent indwelling period, three of which proved to be statistically significant. Data from this group can be viewed in Table 2. Also, noted was the further distal the stone was at initial diagnosis the more likely spontaneous stone passage occurred. Following stent removal, patients with smaller stones were again more likely to spontaneously pass them. Surprisingly, the more a stone traveled with an indwelling stent, the more likely it was to spontaneously pass after stent removal. Data collected after stent removal is recorded in Table 3.
From this data, Dr. Piet Bosshard and his team were able to devise a proposed treatment strategy based on the location of the ureteral stone. For management in distal ureteral stones, it is recommended to remove indwelling stents for stones <5mm in diameter, which led to spontaneous passage in 90% of cases. In larger stones, spontaneous passage only occurred in 10% of cases and patients should be offered secondary intervention prior to stent removal. For proximal or mid ureteral stones, it is proposed to evaluate the stone movement with an indwelling double J ureteral stent. Removal of an indwelling stent is recommended when these stones move distally ≥5cm due to a 95% chance for spontaneous stone passage. In cases with no movement, only 4% of cases resulted in stone passage and patients should be given the option of secondary intervention prior to ureteral stent removal.
In conclusion, indwelling double J ureteral stents should be removed at least one day prior to scheduled URS or ESWL for treatment of ureteral stones. Double J ureteral stents were successfully able to dilate the ureter to allow passage of the ureteral stone(s), avoiding stone surgery all together. During questioning, it was asked if any post-stent pull imaging was done during this study. After stent removal, patients would filter their urine. Patients were discharged if they passed a stone or kept for further X-Ray or low dose non-contract CT imaging if stone passage was questioned. The ureteral stent size used for each patient was also brought to question. All participating patients received a 6 Fr silicone ureteral stent. At the end of the discussion, the rarity of this type of data and implications the results suggest for future ureteral stone treatment was noted.
Presented by: Piet Bosshard, MD, Bern, Switzerland
Written by: Christina Kosmala, Department of Urology, University of California at American Urological Association's 2019 Annual Meeting (AUA 2019), May 3 – 6, 2019 in Chicago, Illinois