Percutaneous nephrolithotomy versus retrograde intrarenal surgery for the treatment of kidney stones up to 2 cm in patients with solitary kidney: a single centre experience
Bai et al. BMC Urology
Percutaneous nephrolithotomy versus retrograde intrarenal surgery for the treatment of kidney stones up to 2 cm in patients with solitary kidney: a single centre experience
Yunjin Bai 0
Xiaoming Wang 0
0 Equal contributors Department of Urology, Institute of Urology, West China Hospital, Sichuan University , Chengdu , China
Background: To compare the treatment outcomes between percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) for the management of stones larger than 2 cm in patients with solitary kidney. Methods: One hundred sixteen patients with a solitary kidney who underwent RIRS (n = 56) or PCNL (n = 60) for large renal stones (>2 cm) between Jan 2010 and Nov 2015 have been considered. The patients' characteristics, stone characteristics, operative time, incidence of complications, hospital stay, and stone-free rates (SFR) have been evaluated. Results: SFRs after one session were 19.6% and 35.7% for RIRS and PCNL respectively (p = 0.047), but the SFR at 3 months follow-up comparable in both groups (82.1% vs. 88.3%, p = 0.346). The calculated mean operative time for RIRS was longer (p < 0.001), but the mean postoperatively hospital stay was statistically significantly shorter (p < 0.001) and average drop in hemoglobin level was less (p = 0.040). PCNL showed a higher complication rate, although this difference was not statistically significant. Conclusions: Satisfactory stone clearance can be achieved with multi-session RIRS in the treatment of renal stones larger than 2 cm in patients with solitary kidney. RIRS can be considered as an alternative to PCNL in selected cases.
Solitary kidney; Retrograde intrarenal surgery; Percutaneous nephrolithotomy
Renal calculi, especially large stone, are very dangerous
for patients with solitary kidney. They may cause urinary
tract infection, anuria, renal insufficiency or sepsis .
Therefore, stones in patients with solitary kidney need
active treatment. The management of stones in this
cohort as yet remains a challenging scenario, complete
removal of the stone and protection of the renal function
through safely surgical treatments is critical [1, 2].
Percutaneous nephrolithotomy (PCNL) is the mainstay
of management for large (> 2 cm) or complicated renal
stones . Although this technique affords high success
rates and accelerated stone clearance, regardless of stone
composition and size , it is an aggressive treatment
with severe complications for patients with solitary
kidney. These patients are likely to have increased thickness
of the renal parenchyma as a consequence of the
compensatory hypertrophy, thus they are more likely to
suffer bleeding when be treated with PCNL than patients
with bilateral kidneys . In addition, significant
bleeding in these patients means potential acute renal failure
due to urinary obstruction by blood clots and the
absence of supplementary renal function of the other
kidney . Perhaps anatomically oriented access can be
made so that the risk of this complication is minimized,
but cannot be totally avoided.
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In the past few years, improvements in endoscopy
technology make retrograde intrarenal surgery (RIRS)
more attractive, even for special circumstances, which
has been used as an alternative option to PCNL for renal
stones with a low complication rate . In patients
contraindicated for PCNL and with unfavorable treatment
characteristics, such as morbid obesity, advanced
vertebral deformities, serious cardiopulmonary diseases or
those receiving anticoagulant treatment, RIRS is a
reliable choice . Which is a preferable treatment method
for preserving functioning renal parenchyma , and
this is crucial to the management of patients with
solitary kidney . Unfortunately, RIRS cannot be
recommended as first-line treatment due to which stone-free
rate (SFR) showed a negative correlation with stone size
. SFR after RIRS was achieved in 30% of patients with
>2 cm stones and usually needed re-treatment; however,
overall complication rates not related to stone sizes .
Therefore, patients with >2 cm stones should be
counseled individually as staged procedures often required to
remove calculi from the kidney without compromising
the safety of RIRS. In addition, one concern about
performing RIRS in a solitary kidney is the risk of renal
function injury. Recently, Kuroda and coworkers 
have shown that no significant difference was found in
term of the change in glomerular filtration rate after
RIRS between patients with solitary kidney and bilateral
Current guidelines do not provide clear
recommendations concerning the management of renal stones in
patients with solitary kidney. Selecting the optimal
management strategies for this cohort can be
challenging, as each treatment modality has unique advantages
and disadvantages. In the present study, we compared
the efficacy and safety features between PCNL and RIRS
with a flexible ureteroscope in the treatment of > 2 cm
renal stones in patients with solitary kidney.
After approval was obtained from the Institutional
Review Board, the data of 116 consecutive patients with
solitary kidney underwent PCNL or RIRS with a flexible
ureteroscopy for kidney stones between January 2010
and November 2015 at our institution were
retrospectively reviewed. Solitary kidney is identified as patients
with either functional or anatomical solitary kidney.
Solitary functional kidney is defined as patients whose
preoperative evaluation showed a contralateral kidney
function is < 5% in split renal function on a
99mTclabeled dimercaptosuccinic acid single-photon emission
computed tomography or drip infusion pyelography
showed the contralateral kidney was significantly
atrophic and had no urine secretion. The decision to
perform PCNL or flexible ureteroscopy was based on
individual surgeon discretion and patient selection.
Patient assessment before surgery included
historytaking, clinical examination, laboratory examination,
ultrasonography, plain radiograph of kidney-ureter-bladder
(KUB), and non-contrast computed tomography (CT).
Grade of hydronephrosis was categorized as none, mild,
moderate, or severe, based on the appearance of the pelvis
on ultrasonography and the presence of calices and/or
parenchymal atrophy. Stone size was measured
preoperatively and calculated as the sum of the largest axis of each
stone on CT.
The operation time was defined as the time from the
start of the first procedure to the termination of the
surgical operation. For PCNL and RIRS, it was started
with the puncture for an access tract and placement of
flexible ureteroscope, respectively. The duration of
hospitalization was defined as the time from the day of
surgery to discharge for each session. Stone-free status
was assessed by ultrasonography and/or a KUB, and
was defined as the absence of any stones.
Complications were classified using the Clavien-Dindo
classification system .
Under general anesthesia and prone position, an 18
gauge needle was placed into proper calyx under C-arm
fluoroscopy guidance. After a guidewire was inserted
and fixed, dilation was performed serially with a fascial
dilator up to 24 F and a 26 F sheath was placed through
the tract. With using 8/9.8 F rigid ureteroscope, stone
disintegration was performed using holmium laser and
fragments were removed by flushing or forceps. An 18 F
nephrostomy tube was placed at the end of the
operation in all cases and usually removed on the fourth day
after surgery, provided that there was no complication
or the nephrostomy tube is draining clear urine.
Generally, a 6 F ureteral stent was placed 10–14 days
before RIRS to relieve acute obstruction and infection, or
to dilate the ureter for passage of the ureteroscope.
Under general anesthesia, patients were positioned in
lithotomy position. After two guidewires were advanced
to the renal pelvis, a ureteral access sheath was
implanted and a 7.5F flexible ureteroscope was inserted
along the guidewires. Fragmentation of the stone burden
was accomplished with a 4–12 W Holmium laser and
then removed using stone basket. If operative time
exceeded 90 min, we discontinued the procedure to
minimize perioperative complications. At the end of the
operation, a double-J stent was implanted in the pelvis
routinely. KUB was taken on the first day after RIRS to
assessed the residual stones and the location of the
stents. Patients were reevaluated on the first and third
postoperative month with laboratory examination, and
KUB or CT scan. The double-J stent was removed under
local anesthesia, as appropriate.
The SPSS 19.0 software was used for all data analyses.
Categorical variables were presented as number of
subjects (n) and percentage (%), and analyzed using the
Chi-squared or Fisher’s exact test as appropriate. The
continuous data were presented as mean ± standard
deviation and analyzed using the independent samples t
test of variance. A two-sided p < 0.05 was considered to
be statistically significant.
tract infection requiring additional antibiotics were
comparable between the two groups. Every group
had one patient developed sepsis. The mean drop in
the postoperative hemoglobin concentration in PCNL
group was significantly higher than that in RIRS
group (p = 0.004), and blood transfusions were
required in 7 (11.7%) patients in the PCNL group. No
nephrectomy or angioembolization was required.
There was no significant difference between the two
groups in stone compositions (p = 0.307).
Table 1 Clinical data of patients in PCNL and RIRS groups
Laterality, left, n (%)
Stone size, mm(range)
Site of stone, n (%)
Hydronephrosis, n (%)
Moderate or severe
Stone composition, n (%)
Recurrent stone former, n (%) 26 (43.3)
PCNL (n = 60)
78.75 ± 27.0 (42–141)
13.3 ± 6.6 (1.1–37.4)
RIRS (n = 56)
99.1 ± 29.5 (45–157)
10.2 ± 4.4 (2.8–21.3)
110.6 ± 38.1 (40.5–212.9)
131.7 ± 57.4 (28.4–308.7)
113.8 ± 44.5 (18–263.4)
136.6 ± 56.8 (28.8–305.5)
Table 2 Perioperative and Postoperative Data
Operation time, min (range)a
Postoperative hospitalization time, d (range)a
Drop in Hb level in g/dl (range)
Initial stone-free, n (%)
Auxiliary procedures, n (%)
Shock wave lithotripsy
Final stone-free rate, %
Preoperative serum creatinine in umol/L (range)
Postoperative serum creatinine in umol/L (range)
Complications (Clavein classification), %
Urine leakage < 12 h(G II) (%)
Transfusion (G II) (%)
Steinstrasse (G IIIa) (%)
Sepsis (G IVa) (%)
Urinary tract infection requiring additional antibiotics (G II) (%)
ainitial procedure plus auxiliary procedure
Nowadays, the surgical management of renal stones has
been dramatically changed because of tremendous
reformation in endoscopy technology. As increased risk of
perioperative complications and impairment of renal
function for patients with solitary kidney during surgical
management , thus, which surgical approach use
continues to be of significant concern. In the era of
minimally invasive surgery, RIRS and PCNL are two major
surgical techniques for removing large renal stones ,
and PCNL has become the standard treatment with
which all other approaches should be compared. A
number of pertinent questions remain without conclusive
answers, despite various studies reported in the literature,
such as: how safe are PCNL or RIRS? What are the
factors that portend a poor outcome with PCNL? How do
complications compare PCNL with RIRS? Our results
suggested that both PCNL and RIRS can safely be
carried out for patients with solitary kidney. Final SFRs
were similar in both groups. The main advantage of the
RIRS over PCNL seems to be the less of mean decrease
in the hemoglobin level. However, RIRS often required
The primary concern of PCNL in solitary kidneys was
the risk to develop complication such as severe
uncontrollable bleeding that may cause an anephric state. The
over complications after PCNL in these patients was
30.6%, of which 5.6% required blood transfusion . Risk
factors for serious bleeding include upper calix puncture,
large stone, multiple tracts, inexperienced surgeon, and
solitary kidney . It was reported that the need for
blood transfusion and the risk of severe bleeding were
higher after PCNL in solitary kidneys compared to
bilateral kidneys . Hosseini and colleagues performed
PCNL on 412 patients with solitary kidney, 19 (4.6%)
patients encountered bleeding requiring transfusion, but
none of them required nephrectomy . Compensatory
hypertrophy is common in solitary kidneys with
increasing thickness of the renal parenchyma. It was speculated
that access through such thick renal parenchyma may
increase the risk of bleeding .
Continuous improvements in instruments and
techniques of PCNL have helped urologists to perform this
procedure with high levels of safety and efficacy in
challenging cases such as stones in solitary kidneys .
Previous study reported that PCNL is a safe and efficient
treatment for patients with solitary kidney despite the
lower SFR (82.1% vs. 83.5%; p = 0.970) and increased
morbidity (21.5% vs. 17.3%; p = 0.287) compared to
patients with bilateral kidneys . A recent systematic
review confirmed the efficacy of PCNL for stones in
patients with solitary kidney with initial and overall SFRs
of 78.1% and 86.8% respectively . It is surprising that
PCNL for renal stones in these patients provided
significant improvement in renal function . In another
study, Zeng and colleagues  compared the treatment
outcomes between minimally invasive PCNL and RIRS
for stones larger than 2 cm in patients with solitary
kidney. They found SFRs after a single procedure were
71.7% in the minimally invasive PCNL group and 43.4%
in the RIRS group (p = 0.003), and both groups with
similar complications rates. Our single-session SFR in
both groups was relatively low (35.7% vs 19.6% in the
PCNL and RIRS groups, respectively). This may be
related with that majority patients in our center had more
complicated stones. In addition, the main reason for
PCNL had a higher initial SFR than RIRS is that larger
fragments fall back to the lower calix during RIRS.
Although SFR of RIRS is inferior to that of PCNL ,
considering patients with solitary kidney have the
potential to encounter serious systemic disease, RIRS should
always be considered at any time due to its efficacy and
minimally invasive. Good outcomes of RIRS in terms of
morbidity rate may be outweighed by its SFR in some
cases, which is not neglected, especially in patients with
solitary kidney. Bryniarski et al.  assessed outcomes
after RIRS and PCNL. They found that transfusion
required in 13 of PCNL patients and no transfusion in
the RIRS patients. Gao et al. have reported 26.6%
(12/45) patients of RIRS encountered complications
and 20% (9/45) were identified as I Clavien grade and
no patients required blood transfusions. For our study,
no major complications occurred and minor
complications often were experienced. In our series, a 6 F stent
had been routinely placed 10–14 days before RIRS to
relieve acute obstruction and infection, which may be
account for the infectious complications were also
comparable between the two groups.
RIRS has been frequently considered in the treatment of
larger renal stones as an alternative to PCNL. Although
hemorrhagic diseases are often regarded as
contraindications for both PCNL and SWL, RIRS demonstrated pretty
safety in these patients . Furthermore, with the
increasing numbers of obese and morbid obese patients, the
status of PCNL for renal stones may face challenges
because great skin-kidney distance in these patients may lead
to the puncture needle cannot reach the kidney.
Fortunately, RIRS can be executed without limited outcomes
for obese patients .
Stones in solitary kidney represent a management
dilemma for the urologists. PCNL and RIRS are widely
known to decrease surgery-related morbidity, while
complete removal of calculi in solitary kidney from a
single percutaneous or nature tract was difficult. Zhong
et al  reported that combined use the two techniques
can extract the calculi quickly, shorten operation time,
make a high SFR. In addition, combined therapy can
reduce the need for the number of tracts and then reduce
the loss of blood and potential complications related to
multiple tracts. Therefore, combined therapy can be
used as a feasible treatment option for large renal stones
in patients with solitary kidney.
RIRS is often performed as an ambulatory surgery in
the Western countries. For patients and hospitals, they
will choose RIRS as it is a less invasive treatment with
less length of hospital stay. Under the culture
background and the health insurance policy in China, both
PCNL and RIRS were done as inpatient surgical
procedure. Our patients are usually unwilling to discharge with
the nephrostomy tube in place, thus, the hospital stay
was longer in the both groups in our country. In
addition, the solitary kidney patients in our series with
large stones, treatment should be more careful and
postoperative observation period needs to be extended. Our
results are in line with other researches on RIRS or
PCNL for large stone in China in term of hospitalization
time [2, 15].
Our study has several limitations. First, this study was
a retrospective design undertaken at a single center with
a limit number of patients, we cannot eliminate the
potential selection bias. Additionally, PCNL or RIRS in
solitary kidney is a relative uncommon surgery and
prospective design is challenging to be performed.
Furthermore, the follow-up period of 3 months was quite short.
We might not have detected the longer-term
complications such as hypertension, renal impairment or ureteral
For larger than 2 cm renal stones in patients with
solitary kidneys, PCNL offers initial SFRs superior to those
of RIRS. However, satisfied outcomes can be acquired
with multisession RIRS. Furthermore, hospital stay and
complications of PCNL can be significantly reduced with
RIRS. Therefore, RIRS represents a good alternative
treatment to PCNL in well selected cases with larger
renal stones in patients with solitary kidneys.
CCS: Case-control study; CI: Confidence interval; LPL: Laparoscopic
pyelolithotomy; MD: Mean difference; NOS: Newcastle-Ottawa Scale;
OR: Odds ratio; PCNL: Percutaneous nephrolithotomy; RCT: Randomized
controlled trial; SFR: Stone-free rate; UTI: Urinary tract infection
Availability of data and materials
The datasets supporting the conclusions of this article are available in the
West China hospital Medical Records Room data base (Chengdu, Sichuan,
China) repository. In additional, the datasets analyzed during the current
study is available from the corresponding author on reasonable request.
Conceived and designed the experiments: PH and JW. Analyzed the data:
JYB and XMW. Contributed reagents/materials/analysis JYB and XMW. Wrote
the manuscript: JYB. Designed the software used in analysis: YBY. All authors
read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Ethics approval was obtained for this study from the University of Sichuan
Institutional Review Board. The informed consent was waived because the
study was retrospective in design.
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