Discussion
Renal and proximal ureteral stone disease is a common condition
worldwide. The lifetime risk of urolithiasis is 13% in men and 7% in
women [11]. In recent years, RIRS is widely used in surgical
procedures in urology, as in other surgical departments, due to the
tendency toward minimally invasive options. RIRS has been compared with
other therapeutic modalities in terms of stone-free status and
complications [12,13]. The stone-free rate of this surgical
procedure in our series was 83.6%, and the final stone-free rate after
re-procedure was 94.4%. In the literature, the stone-free rate is
reported to range from 69.7 to 97% [14-16]. Although minor
complications are common after RIRS, major complications such as severe
bleeding and sepsis may also develop [17]. Breda et al. reported
complications in 8% of the patients after RIRS, and major complications
were present in 1.9% [18]. SCS and MCCS are the most widely used
surgical complication classification systems in the urology discipline
[9,10,19]. Although there are a few studies reporting complications
related to the use of flexible ureteroscopy, only limited research has
attempted to standardize complications using these new classification
systems. In our study, the incidence of intraoperative events or
complications was 153 (16.1%) according to SCC and the incidence of
postoperative complications was 121 (12.6%) according to MCCS.
In a recent study by the Clinical Research Office of the Endourological
Society, the data of 11,885 patients (1852 with only renal stones, 8676
with only ureteral stones, and 1145 patients with both types of stone),
who underwent ureteroscopy in 114 centers in 32 countries, were
prospectively examined [16]. The postoperative complication rate was
reported as 3.5%, and most of the cases that developed complications
were Clavien grade 1 or 2 (2.8%). Intraoperative complications were
also reported separately, including bleeding (1.4%), perforation
(1.0%), ureteral avulsion (0.1%), and conversion to open surgery
(0.1%). The most frequent complication in that series was fever (1.8
%). Bleeding was reported at a rate of 0.4%, and a blood transfusion
was required in 0.2% of patients. In addition, sepsis developed in 38
(0.3%) patients, and mortality in five patients for various other
reasons. SCS is the most common classification system used in
classifying intraoperative adverse events [9]. In our series, Satava
grade 1 was seen in a total of 60 patients. However, there were six
(0.6%) patients with malfunctioning or breakage of instruments in the
Satava 1 group. We consider that it is not appropriate to evaluate this
as an intraoperative complication. This situation should be referred to
as an intraoperative event, not as a complication. In addition, the most
common intraoperative complication in our patients was minimal mucosal
injury (3.7%). However, grade 3 complications were not observed. The
most common grade 2b complication was requirement of repeat RIRS (5.6%)
after the stone could not be accessed for various reasons. Among the
patients with grade 2b complications, the surgery had to be terminated
early in six (0.6%) due to vision impairment caused by severe bleeding.
Nevertheless, all of these bleedings were self-limited and did not
require a blood transfusion or surgical intervention. While minimal
mucosal erosions or tears (grade 1) can heal conservatively without a DJ
stent, severe mucosal injuries, such as ureteral perforation (grade 2),
are mostly treated by placing a DJ stent. In a study by Ural et al.,
mild mucosal injury was seen in only 10 (4.3%) patients, and serious
mucosal cleft was observed in three (1.3%) patients and treated by
inserting a urethral DJ stent [17]. In our cases, mild and severe
mucosal injuries were rare, similar to the literature. Traxer et al.
reported that preoperative ureter stenting reduced the risk of severe
ureteric injury by 7 times [13]. In our study, no statistically
significant relationship was found between preoperative stenting and
absence of complications, and the relationship between preoperative DJ
insertion and ureteral injury was not evaluated in our series. Although
SCS includes the minor complications mentioned above, conditions such as
fever and sepsis are not classified in this system. We consider that SCS
evaluates whether the outcome of the operation is a success because it
is based on whether the operation is to be completed then or postponed.
We think that malfunctioning or breakage of instruments is not a
complication, and therefore they should not be included in SCS.
Breda et al. reported the overall complication rate for RIRS as 8% and
the major complication rate as 1.9% according to MCCS [18]. In a
prospective randomized study by Sabnis et al. conducted with 35 patients
that underwent RIRS, the rate of Clavien grade 1 complications was
determined as 11.4%, but no other complication was reported [20].
In our series, 76% of the patients that developed complications were
classified as grade 1. Major complications were observed in 18 (1.9%)
patients. Two patients had a ureteral stricture (0.2%), one had
urosepsis (0.1%), and a further two died due to urosepsis (0.2%).
Therate of postoperative fever resolved with an antipyretic was
consistent with the literature in our study, but the rate of fever
requiring antibiotic replacement (grade 2) was lower in our study
[21]. In a study by Tian et al., the rate of fever was found to be
17.5%, and diabetes mellitus, elevated preoperative C-reactive protein
(CRP), high stone burden, positive stone culture, and positive renal
pelvis culture were shown to be among the reasons that could cause fever
[22]. In another study, Yong et al. showed that operative time was
an important factor for postoperative fever [21]. In our series,
operative time was longer in the complication group. In the subgroup
analysis performed, operation success was found to be the factor
affecting major (>grade 3) complication. We consider that
factors that affect the success of the operation, such as stone size and
density, also indirectly affect the probability of major complications.
In the literature, postoperative hematuria has been reported at a rate
of 5-7.1%, and it has been emphasized that the use of stone burden, a
high CT attenuation value, or use of UAS increased the incidence of
postoperative hematuria [21,23]. In a study conducted by Shah et
al., it was stated that postoperative hematuria was common in patients
with stones of high CT attenuation, which was caused by increased
mucosal damage as a result of more effort being required to fragment the
stone [24]. In our study, postoperative hematuria was the second
most common complication with a rate of 3.6% and was found be related
to increased stone burden, presence of residual stone, and operative
time while there was no relationship between the use of UAS and
postoperative hematuria development. Although postoperative hematuria is
more common in patients with low CT attenuation values, it is evaluated
as borderline non-significant. This situation can be explained by the
prolongation of operative time as a result of the decrease in the
detection of stones with low HU values on fluoroscopy. This idea is
supported by the statistically significant negative correlation between
HU and operative time and the significant relationship between operative
time and postoperative hematuria development.
Although other complications are extremely rare, they can lead to
serious situations if they occur. Post-RIRS sepsis is one of the most
serious complications [25]. In a retrospective study by Fan et al.,
sepsis was seen in two (0.88) patients after RIRS, and the infective
complication rates were found to vary between 1.7 and 18.8% [26].
Berardinelli et al. reported the rate of sepsis to be 0.7% [27]. In
our series, sepsis was observed in three (0.3%) patients, which is
consistent with the literature. In studies evaluating factors related to
the development of infective complications, pyuria, operative time,
infection stones, diabetes mellitus, elevated preoperative CRP, high
stone burden, and positive stone culture were found as independent
predictive factors [22,26]. In addition, another major complication,
steinstrasse, was observed at a rate of 1.9% in aprevious study
[21]. In our study, non-obstructive steinstrasse was detected at a
rate of 0.6% and obstructive steinstrasse at 0.5%. Ural et al.
determined that the rate of major complications according to SCS was
8.9% [17]. Abnormal renal anatomy and presence of multiple stones
each increased complication development by 2.7 times while the
stone-free status decreased complication development by 4.2 times.
According to MCCS, stone-free status was determined as an independent
predictive factor in the development of major complications. In
addition, according to SCS, stone size, stone density, and fluoroscopy
time were independent risk factors in predicting the requirement of
endoscopic, open or laparoscopic treatment.
The main limitations of our study are that it had a retrospective design
and the operation was performed by specialists with different surgical
experience. Another limitation is that we did not examine factors that
had been previously shown to be associated with the development of
complications, such as CRP, stone culture, and stone type, nor did we
evaluate late-term complications.