There are many treatments for impacted upper ureteral stones, including URSL, MPCNL, and RPLU. Because impacted stones usually are wrapped around or adhere to an ureteral polyp, ESWL is often not effective [18]. Indeed, White et al. reported that if upper ureteral stone diameter was smaller than 10 mm, stone clearance rate by ESWL was 69%, however; when the diameter was larger than 10 mm, it was 59% [18]. It was also reported that when upper ureteral stones are larger than 10 mm, stone clearance rate by ESWL was only 42% [19].
Each method has its pros and cons. Indeed, RPUL takes a long time, but has more chance of success and a lower requirement for ESWL; it also results in fewer complications, but the surgeons have to be adept at local anatomy [10]. PCNL has a good efficacy, but may result in large surgical trauma and bleeding, complicating the recovery of the patients and prolonging hospitalization [10, 20]. URSL is not as effective as RPUL and PCNL, and is prone to move the calculi upward; nevertheless, the surgical trauma by URSL is minimal, leading to short recovery [10, 21]. A meta-analysis by Torricelli et al. [14] showed that the outcomes of RPUL were more favorable than for semi-rigid ureteroscopic lithotripsy, making it the treatment of choice when flexible ureteroscopy is not available.
Ureteroscopic surgery is a minimally invasive procedure, which has a good acceptance for patients and the patients restore quickly after operation. In this study the success rate was 62% and the stone clearance rate was 72% 1 month after operation in the URSL group. The success rate was previously reported to be 35–87% by URSL [22, 23]. Usually, general anesthesia is required in MPCNL and RPLU, while URSL can be performed under spinal anesthesia. So, URSL is especially appropriate for patients who are not suitable for general anesthesia.
However, there are several disadvantages with URSL when dealing with impacted upper ureteral stones. Firstly, the stone clearance rate is relatively low. In most cases, the stones are large and near to renal pelvis. During URSL, the stone and its debris are inclined to return to the renal pelvis under the flushing fluid, resulting in residual stones. Secondly, ESWL is often needed as auxiliary treatment after surgery. Chen et al. [24] reported that ESWL as an auxiliary procedure was 16%. In our study, as an auxiliary procedure, the ESWL treatment rate was 32.6%.
In this study, there were two cases of ureteral stricture postoperatively in the URSL group, which may correlate with long-term obstruction, chronic inflammation and polyp proliferation. Moreover, the holmium laser crushed the stone at an identical spot during the operation time, which would aggravate the ureter mucosal membrane damage, inevitably resulting in occurrence of ureteral stricture. For these patients, we suggest that the double-J stent indwelling time should be increased to 8–12 weeks. Regarding the obvious polyp proliferation cases, urotroscopy was required to detect ureteral stricture when the double-J stent was removed.
With the improvement of endoscopy and lithotripsy instruments in the last decade, PCNL, instead of open surgery, has already become an option for minimally invasive lithotripsy for kidney stones and is gradually being adopted for upper ureteral stones [11, 25]. Karami [26] and colleagues compared URSL and PCNL in 70 cases of upper ureteral impacted stones >1 cm. The results showed that the stone clearance rate was 96% in the PCNL group, while the stones of 32% patients in the URSL group returned to the renal pelvis and needed ESWL after surgery. The authors thought that PCNL was the first choice for these kinds of stones. A similar conclusion was drawn in another study of 53 patients who underwent either PCNL or URSL. The stone-free rate at 1-month follow-up was 95.4% in the PCNL group and 58% in the URSL group, and eight patients had upward migrating stones during the URSL procedure; they were treated by ESWL [27]. Out results show that the stone clearance rate was 96% 1 month after surgery in the MPCNL group. We found similar results when comparing URSL and MPCNL, but the complications in the groups were similar. In our opinion, intrapoerative puncture is not difficult for cases of moderate or severe hydronephrosis resulting from upper ureteral impacted stones.
RPLU was first reported by Gaur [28] in 1994. As we know, RPLU has many merits, such as high stone-free rate, less blood loss, less incision pain, and shorter hospitalization time [29]. Therefore, RPLU should be considered for safe and effective treatment for reducing ureteral obstruction in selected patients with large proximal ureteric stones [6, 15, 30, 31]. In this study, the stone-free rate was 100% 3 days after operation in the RPLU group.
We realized that RPLU should be selected for upper ureteral stones when they are combined with mild hydronephrosis, when the ureteropelvic junction is angled, or when it is difficult for PCNL to arrive at the stone position. If the stone is near to the UPJ and hydronephrosis is obvious, the possibility of stones going back into the renal pelvis during the operation increases greatly, which will affect the success rate of the RPLU procedure. In this study, there was no ureteral stricture after RPLU during the long-term follow-up, which might contribute to ureter incision going along the ureteral axis and little heat damage of the ureteral mucosal membrane. However, impacted stones might adhere to the ureteral wall so closely that it is difficult to identify the ureter and remove the stone using RPLU [27]. Therefore, RPLU should only be conducted by urologists who have mastered the subtle skills needed for the laparoscopic technique.
This study has some limitations. The sample was from one single center. Although it was larger than many studies, it remains quite small. Studies from multiple centers would provide more weight to these results. There was no postoperative CT examination 1 month after the operation when the stone clearance rate was calculated. The follow-up of 6–12 months was quite short, so we cannot provide any comparison of recurrence rates or long term complications between the groups.