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.