EURURO Vol. 72 No. 6

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4. Discussion
In this study we provide multi-center outcome data for
patients undergoing RPL and RNL for the management of
renal stones. We found that the complete SFR after a single
robotic procedure was 96%. Our overall complication rate
was 18.5%, with only 7.4% of patients having a Clavien
3 complication. None of the patients underwent a blood
transfusion or developed sepsis after RPL or RNL. The
procedures were done without the need for renal ischemia,
and in patients undergoing RPL, there was no transgression
of the renal parenchyma.
Robotic stone surgery has previously been shown to be a
reasonable approach for removing large staghorn stones
. Badani and colleagues described robotic
extended pyelolithotomy in 13 patients, in which staghorn
or partial staghorn stones were treated. All but one patient
with a complete staghorn stone had removal of the entire
stone specimen, providing a SFR of 92%. Hemal et al
performed eight cases of robotic-assisted laparoscopic
surgery for primary stone removal, with a SFR of 93.2%.
Ghani et al presented results on three patients with
complex staghorn stones who underwent robotic ana-
trophic nephrolithotomy with cold ischemia of the kidney.
In this select group, however, two of the three patients had
RFs following the procedure. provides a summary of
all studies to date assessing robot-assisted and laparoscopic
approaches to pyelolithotomy and renal stone removal
Our study is the largest series to date
evaluating the safety and efficacy of a robotic approach to
treat renal stones.
The advantage of RPL or RNL is that it results in complete
stone removal in a minimally invasive fashion, reducing the
risk of RFs. Fragments following PCNL have the potential for
long-term morbidity due to need for surgical retreatment.
Raman et al evaluated 42 patients with RFs after PCNL
confirmed on CT, and found that 43% of patients experi-
enced a stone related event at a median of 32 mo, and 61% of
these required a repeat surgical procedure. On multivari-
able analysis, RF size >2 mm was the only independent
predictor associated with a repeat stone event. More
recently, Portis and colleagues assessed long-term
outcomes in 129 patients undergoing PCNL with a mean
follow-up of 5.4 yr. Patients who were completely stone-
free had a lower rate of a repeat procedure (4%), whereas
those with RF >2 mm or even <2 mm, had repeat procedure
rates of 30% and 33%, respectively. This implies that even
small RFs <2 mm may have significant consequences, and
that a zero-fragment outcome has the most desirable result.
Robotic minimally invasive surgery offers the possibility of
a one-stop solution for the removal of large renal stones,
and permits a zero-fragment nephrolithotomy, that is zero
fragmentation with the aim of intact complete stone
removal. The appeal of a single definitive procedure is
strong and robotic pyelolithotomymay be the best option in
some cases . There are select indications when
nephrolithotomy is feasible, such as when the overlying
parenchyma for a peripherally located stone is thin or the
stone is in a calyceal diverticulum.
RPL allows removal of stones through an incision of the
renal pelvis without transgressing the parenchyma, which
is a potential cause for bleeding and nephron loss. A select
group of patients that one could consider RPL include
patients with unfavorable anatomy, anticoagulated
patients, concomitant ureteropelvic junction obstruction,
ectopic kidney, and failed PCNL . We acknowledge that
robotic surgery should not be the initial treatment choice
for most patients with renal stones, and that endourologic
management is the standard of care. A further point
regarding RPL is that in some patients, dissection of the
renal pelvis can be challenging as the pelvis may be
inflamed with adherent fat, making demarcation of planes
difficult with bleeding encountered.
RNL may be the better option in cases where access to
the collecting system through the renal pelvis is restricted.
The robotic ultrasound probe is used to both locate the
stone and plan the incision, which is best if performed in the
thinnest part of the parenchyma. If done appropriately,
bleeding is minimal and clamping not necessary. Further, as
we have shown in the accompanying video, RNL is able to
successfully treat calyceal diverticular stones, especially
posterior lying stones via a retroperitoneal approach. One
note on technique here should be addressed; if the
diverticulum orifice is not well localized, or hydrocalyx is
suggested as a differential diagnosis, we recommend
ablation in order to avoid a urine leak from an unablated
hydrocalyx The advantages of a retroperitoneal
approach are that the bowel and peritoneal cavity are not
transgressed, allowing quicker return of bowel function as
well as a more rapid dissection to the hilum . Dis-
advantages to this approach are that it requires greater
expertise to develop the space, particularly in obese
patients, as well as longer preconsole operative times for
access and port placement as noted in our series.
Some shortcomings of robotic renal stone surgery
compared with PCNL need to be noted. First, PCNL should
be considered the least invasive approach, especially in a
single access approach as there is only one skin incision.
However, with complex stones, multiple tracts for PCNL
may be needed which increases the number of incisions.
[8_TD$DIFF]Second, flexible nephroscopy is more easily performed
during PCNL than via a laparoscopic port. [9_TD$DIFF]Third, in patients
who have soft stones, PCNL with an energy device
incorporating suction may lead to easier stone clearance.
RPL and RNL are more suited for hard stones that can be
grasped and removed intact. [10_TD$DIFF]Finally, data is not clear about
the costs of robotic surgery for renal stones. A recent study
by Hyams and Shah calculated PCNL to cost $19 845 in
the USA. Using robotic partial nephrectomy as a surrogate
for the cost of RPL or RNL, a study by Mir and colleagues
estimates the cost of robotic partial nephrectomy to be $11
962. Charges and ancillary equipment used may vary
between institutions, and comparing costs is difficult.
Limitations of our study include absence of postoperative
imaging in four patients. However, these patients were
assessed intraoperatively under robotic vision, and were
patients who had solitary stones removed intact. Of
23 patients undergoing postoperative imaging, CT was used
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