Discussion

The development of stone push-up during URS was a significant problem that resulted in the termination of urinary stone surgeries in the past. Sun Y et al. reported this rate as 10% for all ureteral stones, while Knispel et al. reported it as 40% for upper ureteral stones.9,10 To address this problem, various manipulations and antiretropulsion devices or techniques have been developed. In an experimental study, Patel et al. showed that the inclination of the patient on the operating table can preclude the development of push-ups during ureteroscopy.11 Zehri et al. reported that gel instillation to the proximal part of the stone increased stone-free rates.12 Dretler demonstrated that a ureteral balloon advanced over a guidewire to the proximal part of the stone is useful in averting push-up.13 A year later, Dretler reported the successful results of a device called a Stone Cone®.14 Wang et al. reported that an N-trap occlusion device is effective in preventing stone migration.15 Heat-sensitive polymers, Lithovac, Lithocatch, Parachute and PercSys devices have also been developed and put into use.16–18 As can be seen here, stone push-up directly affecting stone-free rates and unsuccessful surgery was a situation that occupied the agenda of urology in the past. However, with the introduction of laser lithotripsy and fURS, today stone push-up is no longer such an impediment to successful surgical completion. Even if a ureter stone migrates retrograde to the kidney during URS, the surgeon can continue the surgery by altering the surgical instrument and successfully complete the operation.
It is known that intrarenal pressure increases during both URS and fURS. It has been shown that the use of UAS during fURS significantly reduces intrarenal pressure.19,20 This can be considered an advantage of fURS over URS. However, whether this creates a clinical result in terms of renal functions is a matter of some controversy. In a study conducted on patients who underwent fURS, Yang et al. did not detect a significant increase in creatinine on the first postoperative day and in the 1st month postoperatively in stones smaller than 3 cm, while they reported that there was a significant increase in creatinine on the first postoperative day in stones larger than 3 cm and that this regressed in the first postoperative month.21 Based on this, a temporary deterioration of renal function can be expected, especially in cases where surgery time is prolonged. Öztekin et al. reported that they did not detect a significant creatinine change either preoperatively or postoperatively between the two groups who underwent fURS and URS.22 In this study, although our operative times were not long in both groups, we did not observe a significant difference between pre-and postoperative creatinine levels.
Considering the larger number of manipulations of fURS, operation time is expected to be longer in fURS than srURS. In a study where they compared fURS with srURS in the treatment of upper ureteral stones, Kartal et al. reported that operation times where fURS was performed were significantly longer.4 Similar findings were also reported by Karadag et al.23 Although Özkaya et al. reported that the use of UAS in patients who underwent fURS shortened the operation time compared to those who did not use UAS, Galal’s study comparing fURS with URS showed that operation times where srURS was carried out were significantly shorter.5,24 In our study, although the average length of operations using srURS were shorter than those using fURS, these differences were not statistically significant.
It is evident that the development of push-up in ureter stones during surgery will make a significant difference between fURS and srURS in terms of stone-free rates and surgery success. Researchers have developed antiretropulsion devices to prevent stone push-up.18,25 In addition, methods such as putting patients in the Trendelenburg position or applying gel to the proximal part of the stone have been employed to increase stone-free rates.6,12,26 As the surgical technology and technique of fURS improves, it seems likely that push-up cases that develop during srURS will be able to be treated more easily, and there will no longer be a need for antiretropulsion techniques or devices. However, there are scarcely any studies in the literature comparing the stone-free rates of srURS with antiretropulsion and fURS. In their study, in which they did not use an antiretropulsion device, Karadag et al. reported that stone-free rates were superior when fURS was used compared to srURS both directly after surgery and in the following months.23Similarly, Kartal et al. reported a significant stone-free rate in fURS procedures compared to srURS without antiretropulsion.4 Galal et al. found fURS superior in terms of stone-free rates as a result of their studies comparing rigid URS and fURS, which they performed without using an antiretropulsion device.5 However, they added the comment that if they had used a Stone Cone® or N-Trap basket, a higher rate would probably have been achieved using rigid URS. In our study, stone-free rates were significantly higher when srURS was performed compared to fURS. This may be because we used a Stone Cone® as a standard part of the srURS procedure. In addition, leaving the stone fragments and dust particles in the natural flow path of urine may have given this result.
During URS, the surgeon works in a narrow space and may cause iatrogenic damage to the fragile tissue of the ureter, especially in impacted stones. Furthermore, complication rates are lower when fURS is used.5,27 Özkaya et al. reported that complications such as fever, infection, and unsuccessful surgery are less common when using UAS in fURS.24 Therefore, fURS seems to be a more advantageous method. However, not all the data in the literature supports this point of view. Kartal et al. reported that they could not find a significant difference in intraoperative complication rates between fURS and srURS in upper ureteral stones.4Karadag et al. also reported that there was no difference in intraoperative complications.23 Finally, Galal et al. reported no significant difference between both intraoperative and postoperative complications.5 In our study, no statistically significant difference regarding complication rates was found between the two groups.
In light of all this information, it seems that preferring fURS over srURS in an upper ureteral stone will not make a difference in terms of renal functions; indeed, the possibility of using UAS during fURS may even provide other benefits.24 Although the shorter operation time of srURS in the literature suggests that dusting such stones at the location of impaction in the ureter will give faster results, no significant difference was shown in terms of operation times in this study. While it has been reported in the literature that srURS without using antiretropulsion will obtain a lower score than fURS in terms of stone-free rates, we have shown in this study that srURS using antiretropulsion can be superior to fURS in terms of stone-free rates. Moreover, there is no significant difference between these two surgical options regarding complication rates in upper ureteral stones.
The limitations of our study include a retrospective design, a small sample size, and a short follow-up period. Prospective studies should be conducted with larger patient groups. The advantage of our study is that there are few studies comparing URS or srURS with fURS in upper ureteral stones. In addition, it is a unique study in the literature comparing stone dusting after stone push-up with stone dusting performed in the ureter.