Combined Minimally Invasive Percutaneous Nephrolithotomy and Retrograde Intrarenal Surgery for Staghorn Calculi in Patients with Solitary Kidney
Li X (2012) Combined Minimally Invasive Percutaneous Nephrolithotomy and Retrograde Intrarenal Surgery for Staghorn Calculi in
Patients with Solitary Kidney. PLoS ONE 7(10): e48435. doi:10.1371/journal.pone.0048435
Combined Minimally Invasive Percutaneous Nephrolithotomy and Retrograde Intrarenal Surgery for Staghorn Calculi in Patients with Solitary Kidney
Dehui Lai 0
Yongzhong He 0
Yuping Dai 0
Xun Li 0
Utpal Sen, University of Louisville, United States of America
0 1 Department of Urology, The First Affiliated Hospital of Sun Yat-sen University , Guangzhou, Guangdong , China , 2 Department of Urology, The Fifth Affiliated Hospital of Guangzhou Medical University , Guangzhou, Guangdong , China
Background: To present our experience with simultaneous combined minimally invasive percutaneous nephrolithotomy (MPCNL) and retrograde intrarenal surgery (RIRS) to manage patients with staghorn calculi in solitary kidney, and evaluate the safety, efficiency and feasibility of this approach. Methodology/Principal Findings: The study included 20 patients with staghorn calculi in solitary kidney. Demographic characteristics, stone location and surface area were recorded. After informed consent, the patients underwent one stage MPCNL firstly. Combined second stage MPCNL and RIRS simultaneously were performed at postoperative 5-7 days. Operative parameters, stone-free rate (SFR), stone analyses and complications were evaluated. Serum creatinine (Scr), glomerular filtration rate (GFR) and chronic kidney disease (CKD) were measured preoperatively, postoperatively at 1 month, and each follow-up visit. All patients had staghorn stones involving multiple calyces. The mean stone burden was 1099.96843.95 mm2. All patients had only one percutaneous access tract. The mean whole operative duration was 154.37632.45 min. The mean blood loss was 64 (12-140) ml. The final SFR was 90%. During the 1-month follow-up study period, four patients improved in CKD stage. Two patients who had CKD (stage 5) still needed dialysis postoperatively. Mean Scr of the rest patients preoperatively was 187.16694.12 compared to 140.99657.92 umol/L by the end of 1-month followup period (p = 0.019). The same findings were observed in GFR in that preoperatively it was 43.80624.74 ml/min and by the end of the 1-month follow-up it was 49.55621.18 ml/min (p = 0.05). Conclusions/Significance: Combined MPCNL and RIRS management effectively decrease the number and size of percutaneous access tracts, which is safe, feasible, and efficient for managing staghorn calculi in solitary kidney with satisfactory SFR and reducing blood loss, potential morbidity associated with multiple tracts. The approach did not adversely affect renal function at both short-term and long-term follow-up.
Staghorn calculi are branched stones that occupy the renal
pelvis contain one or more caliceal extensions . A heightened
risk of chronic renal failure and life-threatening urosepsis are
wellknown risks of untreated staghorn calculi, especially for patients
with solitary kidney .Percutaneous nephrolithotomy (PCNL)
has evolved into widely accepted and primary recommended
management for staghorn calculi since its first described in 1976
.However, The stone-free rate (SFR) of staghorn calculi
following PCNL monotherapy is only 74% to 83% .
Furthermore, PCNL among the staghorn patients is associated
with potential risk, such as significant hemorrhage, urosepsis, urine
leakage, uncontrolled hemorrhage, embolization, nephrectomy, or
even death . In patients with solitary kidney, staghorn calculi
occupying several calyces had to require multiple access tracts to
achieve complete stone-free. It may be associated with greater
potential risk. Performing PCNL with a small size tract (1220 F),
named minimally invasive percutaneous nephrolithotomy
(MPCNL), may decrease the injured of the kidney and operative
morbidity, comparing to the standard PCNL with (2630 F) tract
[6,7,8]. But the disadvantages of MPCNL are relatively low
efficiency to fragment large stones and high intrapelvic pressure
than the standard PCNL.
Retrograde intrarenal surgery (RIRS) is become popular,
benefited from the advance in flexible ureteroscopic (FU)
instrumentation and holmium laser lithotripsy. It allows retrograde
access to the entire intrarenal collecting system in treating renal
calculi to achieve complete stone-free, and it is safer than PCNL.
However, RIRS is burdened with high rates of fiber breakage and
lower efficiency in larger stone . Less ideal for manage the
whole staghorn calculi, RIRS can be used as an auxiliary
procedure of MPCNL to reach peripheral renal residual calculi
in patients with solitary kidney, on the purpose of stone-free and
keeping the maximum renal function.
In this study, we evaluated the safety, efficiency and feasibility of
combined MPCNL and RIRS on management of staghorn calculi
in patients with solitary kidney and determined long-term renal
Materials and Methods
We obtained approval for this study from the ethics committee
of the fifth affiliated hospital of Guangzhou Medical College.
Written informed consent was obtained for all the participants in
our study. We performed a retrospective analysis of 20 patients
(staghorn calculi involving multiple calyces) who underwent
singletract MPCNL and RIRS combination for staghorn calculi in
a solitary kidney between July 2009 and March 2011 at the
Urology Department of the 5th affiliated hospital of Guangzhou
Medical College. Stones was divided into complete [7 cases, 35%,
(occupying all calyces and renal pelvis, or filled .80% of the renal
collecting system)] and partial [13 cases, 65%, (occupying renal
pelvis, or at least 2 or more calyces)] staghorn calculi . Stone
burden was assessed as the surface area and calculated according
to the European Association of Urology guidelines .The causes
of solitary kidney were congenital in three cases (15%), previous
contra lateral nephrectomy in 10 cases (50%), and nonperfused
contra lateral in 7 cases (35%).
Patient characteristics analyzed were age, sex, BMI, causes of
solitary kidney, previous renal intervention history, hypertension
and diabetes. Preoperative tests, such as blood routine tests,
coagulation tests, serum biochemistry, urinalysis, urine culture,
ultrasonography and plain X-ray were recorded. Computerized
tomography (CT) was done routinely, in order to analyze the size
and location of the stone, the thickness of renal parenchyma, the
anatomical structure and plan the target percutaneous tract and
calyx. Preoperative antibiotics were administered to the results of
For each patient, serum creatinine (Scr) and glomerular
filtration rate (GFR) were measured before and after the whole
procedure, and each follow-up visit. GFR was calculated using the
Cockroft and Gault formula by Scr [12,13]. Chronic kidney
disease (CKD) was classified by the National Kidney Foundation
Kidney Disease Outcome Quality Initiative (NKFK/DOQI)
classification system . CKD stages 1 to 5 were classified as
a GFR that was normal, mildly, moderately, severely decreased
and a requirement for dialysis or kidney transplantation (greater
than 90, 60 to 89, 30 to 59, 15 to 29 and less than 15 ml/minute,
respectively). The Scr, GFR and CKD stage during preoperative
period were compared with those at the follow-up visit.
One-stage single-tract MPCNL. All procedures were
performed under continual epidural anesthesia. Patients were inserted
a 5 F ureteral catheter into the target ureter and placed a 16 F
Foley catheter in the bladder under lithotomy position. Then,
patients were placed in the prone position with a pillow under the
abdomen. MPCNL was performed under C-arm fluoroscopic
guidance using an 18 gauge needle for access to the target calyx. A
posterior middle calyx puncture via the 11th intercostal space
between the posterior axillary line and scapula line was preferred.
The needle was directed into the papilla of the intended posterior
calyx using the bulls-eye technique . Once the needle was
properly placed into the calyx, a 0.035-inch guidewire was inserted
through the needle into the intrarenal collecting system. Tract
dilatation was serially accomplished using Amplatz dilators from
8 F to 20 F.A matched diameter working sheath was advanced into the collecting system. The stones were fragmented with
a holmium laser or pneumatic lithotripter through an 8.5/12 F
rigid nephroscope (designed by Li Xun, Richard Wolf,
German)(Figure 1), and with CyberwandH dual probe ultrasonic
intracorporeal lithotripter through 18 F rigid nephroscope
(designed by Li Xun, Richard Wolf, German) (Figure 1).
The left valve of nephroscope was connected with an
endoscopic pulsed perfusion pump, and the right valve was
connected with Suction. The big fragments were removed with
a forceps, and small fragments were pushed out with an
endoscopic pulsed perfusion pump and suck out with suction.
During the procedure, remove the stone in the renal pelvis and the
low calyces, as for as possible. Meanwhile, rudely inserting the
nephroscope to arrive the peripheral calyx is not supported.
Finally, a 6 F modified DoubleJ stent, which had two open tails,
was inserted via the percutaneous tract with the assistance of
guidewire, and a matched size balloon nephrostomy tube was
inserted in the involved calyx. The operative duration was
calculated from the time of percutaneous puncture to the
completion of nephrostomy tube placement.
On postoperative day 1 or 2, routine KUB and retrograde
nephrostogram were done in all patients to assess for residual stone
fragments, urinary leakage and infrarenal obstruction. On
postoperative day 5,7, second stage procedure was done for the
Combination of Single-tract MPCNL and RIRS
The procedures were performed under continual epidural
anesthesia. Patients were prepared for Galdakao-modified supine
Valdivia (GMSV) position  (Figure 2). Two groups of doctors
were needed. MPCNL group was doing second stage MPCNL
using the former single-tract access. Briefly, a 0.035 guidewire is
inserted into the renal calyx though the nephrostomy tube. Tract
dilatation was serially accomplished using Amplatz dilators up to
the match size, and working sheath was advanced into the renal
collecting system. Nephroscope was inserted into the renal
collecting system. Simultaneously, RIRS was performed by
another group. (Figure 2). After retrograde pyelography and
placing a safety guidewire, a 12/14 ureteric access sheath was
advanced into the proximal ureter, allowing easy passage of the
7.5 F flexible ureteroscope into the collecting system. The renal stones and collecting system were carefully inspected. Residual
stones in the peripheral calyces, which would have required
a second or third nephrostomy access, were fragmented with
a 200 mm holmium laser fiber. Alternatively, a stone basket or
grasping devices was used to transfer calyceal stones into the renal
pelvis, where the MPCNL group can use concomitant lithotripsy
and remove the fragments efficiency. At the end of procedure, the
collecting system accessible to the rigid and flexible nephroscope
was examined for potential fragments. Patients were discharged
home 2 days after second stage procedure, following removal of
their nephrostomy tube, provided no significant residual stone was
seen on the KUB.
One month after the final procedure, all patients were assessed
by CT to confirm the final SFR. Complete stone-free was defined
as the absence of any fragments in kidney or had clinically
insignificant residual fragments (CIRFs), defined as 4 mm or
smaller, nonsymptomatic, nonobstructive and noninfectious
residual fragments . The Double-J stent would be removed in
the complete stone-free patients.
After the first follow-up evaluation, patients returned for an
assessment with urinalysis, serum creatinine, KUB and urinary
ultrasound was used every 3 months during the first year and every
6 months thereafter. When stones appeared in stone-free patients
or the size of residual stones increased, patients were reevaluated
by CT to guide the appropriate treatment modality.
Statistical analysis was done with SPSS 16.0H for WindowsH.
Continuous variables were compared with student t test and
Wilcoxon test, and Proportions of categorical variables were
analyzed for statistical significance using the Fisher exact test.
Differences resulting in p,0.05 were considered significant.
The study identified 20 patients, including 8(40%) men and
12(60%) women. Mean age was 52.75613.13 years (range 21 to
77) and mean BMI was 22.9863.51 kg/m2 (range 17.76 to 31.99).
Mean stone burden was 1099.96843.95 mm2 (range 291 to
2925).Five patients had a previous renal intervention history in the
procedure side. Six staghorn calculi were in the right side, and 14
were in the left. All patients were suffered from medical
comorbidities (1 cardiac; 2 diabetes; 5 hypertension; 12 renal
failure).15(75%) patients were identified as hydronephrosis,
including 8(40%) mild, 4(20%) moderate and 3(15%) severe.
Preoperative urine cultures were positive in 10 (50%) patients.
All these infections were administrated with culture-specific
antibiotics. Demographic and clinical preoperative characteristics
of patients were shown in Table 1. During the preoperative period,
one (5%) patient had CKD stage 1, four (20%) had stage 2, eight
(40%) had stage 3, five (25%) had stage 4 and two (10%) had stage
5. Two patients required dialysis preoperatively. Table 1. Demographic and clinical preoperative characteristics of patients.
Age, year, mean(SD), range
BMI, kg/m2, mean (SD)
Cause of solitary kidney, no. (%)
Stone side, no. (%)
Staghorn Stone type, no. (%)
Stone burden, mean (SD), range (mm2)1099.9(843.95), 2912925
Grade of hydronephrosis, no. (%)
Medical Comorbidities, no. (%)
All patients had only one percutaneous access tract. Access to
calices through an 11th intercostal route was established in 17
renal units, and sub-12th costal approach was in three renal units.
The mean operative duration was 96.88630.42 min in one stage
and 87.86634.90 min in second stage. The mean whole operative
duration was 154.37632.45 min, which was not significantly
different from previous experience with standard multiple accesses
PCNL had reported [18,19]. The mean blood loss was 64 (12140)
ml, which was less than multiple-puncture PCNL had reported
[18,19]. There was no intraoperative complications in all cases.
Postoperative complications noted in 5(25%) patents according to
the Clavien classification. Four patients had fever on the day 1
after MPCNL, which resolved spontaneously in two, while the
remaining two patients required antibiotic treatment because of
positive urine cultures suggested urinary tract infection, and
positive blood cultures. Two patients were treated with a complete
culture-specific antibiotics until body temperature, urinalysis and
urine culture were normal. One patient was prolonged tract
leakage because of diabetes. No patients required blood
transfusion. Mean hospitalization time was 12.1162.77 days, two
patients prolonged hospitalization time because of poor wound
healing induced by diabetes. The Initial SFR after the procedure
was 95%. One patient had small asymptomatic residual calculi
(largest 6 mm) in the lower pole. Three patients had CIRFs. The
final SFR was 90%, confirmed by CT 1 month after the final
operation. Stone recurred in one patient in the lower pole
(diameter,6 mm, asymptomatic). Operative characteristics and
stone composition were shown in Table 2. During the whole
follow-up period, another patient had recurred stone
(diameter,12 mm, in the upper pole) in postoperative 6 months, who
was treated with RIRS. Stone recurred was not found in the rest
CKD stage was compared in Table 3 before and after the
treatment. During the 1-month follow-up study period, 4 patients
improved to be CKD (stage 3) postoperatively, who were identified
as CKD (stage 4) preoperatively. Two patients who had CKD
(stage 5) still needed dialysis postoperatively. No more patients
progressed to end-stage renal disease requiring dialysis. Mean Scr
of the rest patients before operation was 187.16694.12 umol/L
compared to 140.99657.92 umol/L by the end of 1-month
follow-up period with statistical significance (p = 0.019). The same
findings were observed in GFR in that before operation it was
43.80624.74 ml/min and by the end of the 1-month follow-up it
was 49.55621.18 ml/min with statistical significance (p = 0.05).
However, there were no statistically significant differences between
these parameters from 1 month to 1-year follow-up (p.0.05).
Table 3 also compared Scr and calculated GFR of 18 patients
before and after the treatment.
In patients with solitary kidney, an untreated staghorn calculus
is likely to destroy the renal function and cause life-threatening
urosepsis. Complete removal of the stone is crucial aim to
eradicate any causative organisms, relieve obstruction, prevent
further stone recurrence and preserve the renal function as far as
possible . PCNL is currently the recommended treatment for
patients with staghorn calculi based on the superior outcomes and
acceptable low morbidity, with the advent of endourologic
instruments, lithotripsy devices, and surgical techniques [1,21].
Although rare, PCNL is associated with significant complications,
especially in patients with solitary kidney. One of the most
common and worrisome complications following PCNL is renal
hemorrhage . Because of physiological compensatory
hypertrophy of the renal parenchyma in the solitary kidney, it is more
likely to increase the risk of hemorrhage owe to damaging more
renal tissue and blood vessel in puncturing and dilating the thick
renal parenchyma . Previous study has demonstrated that
compared with the tract of standard PCNL (2630 F), the small
tract (1220 F) of MPCNL obviously reduced the damage of renal
parenchyma and vessel. Although, previous literature has proved
that mean intrapelvic pressures of the minimum tract (14 F) in
MPCNL was still lower than the causing backflow (30 mmHg)
, performing PCNL in lower intrapelvic pressures is effective
to reduce the absorption of toxinum and pyrogen. In this study,
17(85%) MPCNL was performed with 20 F because each effective
lithotripsy can be placed through the nephroscope in this size of
working sheath. Accessing the collecting system through the
posterior middle calyx provided the most direct and shortest tract
from skin to renal collecting system, and may enable to access the
majority of the collecting system. Performing MPCNL by an 8/
9.8 F rigid ureteroscope was usual in the past, with the advantage
of its slender body, which can access to more calyces to acquire
a higher SRF and a lower complication in a single tract [8,25].
However, urologists often complained of fatigue, bad visual fields,
and low efficiency in stone removal, when using ureteroscope.
With the development of endourology, an 8.5/12 F rigid
nephroscope was designed to overcome the disadvantage of
ureteroscope in MPCNL procedure. It not only has a relative
suitable body (12 F), which can access to most calyces, but also had
a wider working channel (8.5 F), which is to facilitate stone
removal with a forceps. Addition, because front mouth of the
nephroscope is flat, the small fragments were pushed out with an
endoscopic pulsed perfusion pump and suck out with suction
easily. The valves of the nephroscope were connected with pulsed
perfusion pump and suction, which can be regulated by the
urologist. This convenient regulated system was used so that
irrigation fluid could escape easily with no increase in the
intrapelvic pressure. An 18 F rigid nephroscope was designed specially
for dual probe ultrasonic intracorporeal lithotripter, which was
a high effective lithotripter in managing large bulk stone with low
intra-pelvic pressure through a single tract.
Access to all the calyces through one percutaneous tract may be
difficult due to the peculiar anatomical structure of the collecting
system. Meanwhile, solitary kidney with large burden stone,
branched stone and satellite stone or residual stone in parallel
calyces of the access often requires multiple access tracts during
PCNL. Furthermore, multiple access tracts may be associated with
greater risk of renal hemorrhage [26,27]. RIRS has been used
successfully to access and treat complex renal calculi smaller than
2 cm with high reported stone-free rates . RIRS has fewer
overall complications compared to PCNL, even absence of renal
injure. However, the small working channels of RIRS had limited
the usefulness of effective instrumentation that allows concurrent
stone fragmentation and removal . Multiple procedures or
combined approach may be required to clear a large stone.
Although, Wong et al  in their study could achieve clearance
rates of 95% in 45 renal units with a single puncture followed by
flexible nephroscopy in a staged manner, SRF after the first stage
was only 51.4%, and flexible nephroscopy with a large diameter
was not easy to access to the narrow calyces. Perhaps, the same
group of patients would have been rendered completely stone free
with the addition of multiple tracts even at the cost of extending
the hospital stay. Landman et al  use simultaneously
ureteroscopy and lower calix single-tract PCNL for single-access
of six complete and three partial staghorn calculi with no major
complication. But SRF was only 78%. Marguet et al  applied
the same concept, albeit with the difference that ureterorenoscopy
Puncture (one staged MPCNL), no. (%)
Posterior middle calyx via 11th intercostal
Posterior lower pole below 12th costal
No. of tracts, no. (%)
Access tract Size, no. (%)
Time to access the collecting system, mean, (SD), range (min)
Residual calculi characteristics after one staged MPCNL
Stone size, mean, (SD), range (mm2)
Stone position, no. (%)
Operative duration, mean (SD), range(min)
Mean blood loss, mean (SD), range(ml)
Stone-free rate, no. (%)
Nephrostomy removal time, Mean, (SD), range (days)
Hospitalization time, Mean, (SD), range (days)
CyberwandH dual probe ultrasonic
Complications of operation, no. (%)
Postoperative fever (.38.5uC)
Prolonged tract leakage
Urinary tract infection
Calcium oxalate and phosphate
was performed firstly to clear the stones in the peripheral calices,
which would have needed a second or third nephrostomy access.
Then the patient was placed in the prone position and single
access PCNL performed to remove the residual stone.
In this study, combination of single-tract MPCNL and RIRS
was performed in the second stage, when the drainage was clear
and the visual fields were well. Take the advantage of single tract
one-stage MPCNL, the residual stone burden can be fragmented
by holmium laser or translocated into the renal pelvis, using
a basket or grasp by RIRS doctor group. Simultaneously, MPCNL
doctor group can manage the stone with effective intracorporeal
lithotripsy or removed them with a forceps easier for previous
access. Despite retrograde irrigation, stone fragments often fail to
clear completely after intracorporeal lithotripsy. Combination of
single-tract MPCNL and RIRS offers a larger bore access that can
allow efficient removal of these remaining fragments. The mean
whole operative duration was not significantly different from
previous experience with standard multiple accesses PCNL had
CKD stage, no. (%)
reported. The mean blood loss was 64 (12140) ml, which was less
than multiple-puncture PCNL had reported by other urologist
[18,19]. The initial and final SFR were 95% and 90%, which was
higher than the PCNL monotherapy (74% - 83%)  and
Landmans study .
Previous study has demonstrated that no significant change in
estimated Scr and GFR under PCNL with solitary kidney [28,30].
However there are at present no available well-constructed trials
comparing the long-term renal effects of multiple-tract PCNL with
single-tract PCNL. According to our surgical approach, regardless
of 2 dialysis patients, a significant improvement in Scr and GFR
was demonstrated. Mean Scr before operation was
187.16694.12 umol/L compared to 140.99657.92 umol/L by
the end of 1-month follow-up period with statistical significance
(p = 0.019). The same findings were observed in GFR in that
before operation it was 43.80624.74 ml/min and by the end of
the 1-month follow-up it was 49.55621.18 ml/min with statistical
significance (p = 0.05). Four patients improved by CKD stage.
However, there were no statistically significant differences between
these parameters from 1 month to 1-year follow-up (p.0.05). As is
known, the most deleterious effect on renal function is neglected
obstruction. If obstruction in a solitary kidney is rapidly relieved
the kidney will regain basal function. It seems that our surgical
approach did not adversely affect renal function.
In conclusion, our surgical approach modified here effectively
decreases the number and size of percutaneous access tracts, which
combines the advantages of both MPCNL and RIRS. It is safe,
feasible, and efficient for managing staghorn calculi in solitary
kidney with satisfactory SFR and reducing blood loss, potential
morbidity associated with multiple tracts. The approach did not
adversely affect renal function at both short-term and long-term
Conceived and designed the experiments: DL YH YD XL. Performed the
experiments: DL YH XL. Analyzed the data: DL YD. Contributed
reagents/materials/analysis tools: DL YD. Wrote the paper: DL.
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