Efficacy of semirigid ureteroscopy with pneumatic lithotripsy for ureteral stone surface area of greater than 30 mm2.
ABSTRACT To study the outcome and safety of semirigid ureteroscopy (URS) using pneumatic lithotripsy for treatment of ureteral stones of surface area >30 mm2 and to assess the impact of size and location on stone-free (SF) rate.
In this study, 265 patients with >30 mm2 isolated ureteral stones treated by semirigid URS were included. URS was performed using an 8F, 7F, or 6.4F semirigid ureteroscopes with pneumatic lithotripsy (Swiss Lithoclast). Stones were fragmented to approximately 2-3 mm particles, and removed. The outcome parameters assessed at 3-month follow-up were SF rate and efficiency quotient (EQ); impact of stone size and site on SF/EQ was also analyzed. The patient demographics, stone, procedure, and patient-related parameters and complications were noted.
At 3-month follow-up overall SF was 74% and EQ 59.2%. SF for 30-100 mm2 and >100 mm2 was 79.2% and 68.5%, respectively (p < 0.003). The SF/EQ for upper, middle, and lower ureteral stones were 59/40.7, 53/37.5, and 92/84.5, respectively (p < 0.001). There was no major complication; the minor complication rate was 12.5%.
Semirigid URS using pneumatic lithotripsy for treatment of stones >30 mm2 is a safe and highly efficacious procedure particularly in the distal ureter. There is a significant difference in the SF and EQ between upper/middle ureteral stone and lower ureteral stone. Stone size has a direct relation with the SF and EQ. Upper ureteral stones have a longer time to SF compared to middle and lower ureteral stones (p < 0.001).
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ABSTRACT: We investigated whether previous intraureteral manipulations had an effect on the stone-free rates (SFR) after semi-rigid ureteroscopy (URS) with pneumatic lithotripsy. A retrospective review of all patients who were treated for ureteral stones at two different institutions from June 2003 through January 2010 was performed. Data of 161 URS procedures were analyzed. Stone size, location (distal, mid and proximal) and number (single and multiple), patient demographics and previous intraureteral manipulations were recorded. Patients were grouped as having undergone a previous ipsilateral intraureteral manipulation (Group 1) or not (Group 2). Stone location and number, stone clearance and ancillary procedures were compared. There were no significant differences between Group 1 versus Group 2 for age (p > 0.05), gender (p > 0.05), stone site (p > 0.05) and stone size (p > 0.05). Stones with multiple locations were more frequent in Group 1 (18.5%); however, the difference did not reach statistical significance between the two groups. Similarly, the frequency of multiple stones was also higher in Group 1 (29.6%). Stone site, diameter and gender were comparable in both groups. Stone-free rate of all patients was 84.6% after the first intervention. This rate increased to 98.1% after secondary procedures. Univariate analysis revealed that SFR after URS were low in patients who underwent previous intraureteral manipulations (Group 1:55.6% vs. Group 2:89.1%). SFR after the first intervention were related with stone size, location and number. Additionally, multiple logistic regression analysis indicated a relationship between previous intraureteral manipulations and initial stone clearance rates. Spontaneous passage of stone fragments after URS was associated with stone burden, location, number and previous intraureteral manipulations. Further multiple logistic regression analysis showed that only previous intraureteral manipulations were associated with the expulsion of the stones left for passage.Urological Research 09/2011; 40(4):365-71. · 1.59 Impact Factor
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ABSTRACT: To examine which parameters should be measured to preoperatively determine the stone burden as predictors of stone-free (SF) status after a single flexible ureteroscopy (URS). Although several stone parameters reportedly influence the outcome of treatment for urinary stones, the most reliable indicators of stone burden remain unclear. Patients with renal stones treated by flexible URS with holmium laser lithotripsy between October 2009 and December 2011 at a single institute were retrospectively evaluated. The SF status was determined by kidney-ureter-bladder (KUB) films at postoperative day 1. Correlations of possible predictors with the SF status were analyzed using a logistic regression model. According to the univariate analysis, the following variables were significantly associated with failed treatment: number of stones (P = .001), cumulative stone diameter (CSD) (P < .001), stone surface area (SA) (P < .001), stone volume (P < .001), and presence of lower pole calculi (P = .008). According to the multivariate analysis, the stone volume (P < .001) and the CSD (P = .015) were found to be independent predictors of SF status. The SA (P = .598) had no significant independent influence on the SF status. Among the several parameters regarding the renal stone burden, the stone volume determined by noncontrast computed tomography and the CSD of the KUB were significantly and independently inversely related to the success rate of URS. Among the 3 parameters of stone burden, the SA was found to have a lower clinical utility and priority as a predictor of a SF status after URS.Urology 05/2012; 80(3):524-8. · 2.42 Impact Factor
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ABSTRACT: Objectives: To investigate the utility and limitations of stone surface area (SA) as a predictor of stone-free (SF) status after a single semirigid ureteroscopy (URS), with or without a flexible component, for the treatment of urinary stones. Patients and Methods: Cases of patients with urinary stones treated by combined ureteroscopy with holmium laser lithotripsy at a single institute were retrospectively evaluated. Correlations of possible predictors with SF status were analyzed using a logistic regression model. Two types of stone surface area were measured, "traced stone surface area" (tSA) and "calculated stone surface area" (cSA). Results: According to the univariate analysis, the following variables were significantly associated with non-SF: stone number (P<0.001), ureteral stone location (P=0.045), presence of renal stones (P<0.001), tSA (P<0.001), cSA (P<0.001), stone volume (P<0.001), and operator experience (P=0.02). According to multivariate analysis, stone volume (P=0.016) was an independent predictor of SF status. The scatter diagrams for tSA and cSA showed strong correlations between these parameters, and Spearman's ρ was 0.975. Conclusions: Stone volume and SA were highly indicative of stone status after single semirigid URS, with or without a flexible component. The formula for cSA, maximum diameter x width x π x 1/4, was demonstrated to accurately represent SA in this study. SA, however, indicated a lower clinical priority and utility as a predictor of stone status than stone volume. The combination of semirigid and flexible URS could access any ureteral stones, including those that semirigid URS alone could not treat. The cut-off points for these predictors of outcome were 110.0 mm2 for cSA, 125.0 mm2 for tSA, and 840.0 mm3 for stone volume.Journal of endourology / Endourological Society 02/2013; · 1.75 Impact Factor
Efficacy of Semirigid Ureteroscopy with Pneumatic Lithotripsy
for Ureteral Stone Surface Area of Greater Than 30mm2
M. Hammad Ather, M.D., FCPS (Urol), FEBU, Syed M. Nazim, MBBS,
and M. Nasir Sulaiman, FRCS, FRCS (Urol), D.U.
Objectives: To study the outcome and safety of semirigid ureteroscopy (URS) using pneumatic lithotripsy for
treatment of ureteral stones of surface area >30mm2and to assess the impact of size and location on stone-free
Patients and Methods: In this study, 265 patients with >30mm2isolated ureteral stones treated by semirigid
URS were included. URS was performed using an 8F, 7F, or 6.4F semirigid ureteroscopes with pneumatic
lithotripsy (Swiss Lithoclast?). Stones were fragmented to *2–3mm particles, and removed. The outcome
parameters assessed at 3-month follow-up were SF rate and efficiency quotient (EQ); impact of stone size and
site on SF=EQ was also analyzed. The patient demographics, stone, procedure, and patient-related parameters
and complications were noted.
Results: At 3-month follow-up overall SF was 74% and EQ 59.2%. SF for 30–100mm2and >100mm2was 79.2%
and 68.5%, respectively (p<0.003). The SF=EQ for upper, middle, and lower ureteral stones were 59=40.7,
53=37.5, and 92=84.5, respectively (p<0.001). There was no major complication; the minor complication rate was
Conclusions: Semirigid URS using pneumatic lithotripsy for treatment of stones >30mm2is a safe and highly
efficacious procedure particularly in the distal ureter. There is a significant difference in the SF and EQ between
upper=middle ureteral stone and lower ureteral stone. Stone size has a direct relation with the SF and EQ. Upper
ureteral stones have a longer time to SF compared to middle and lower ureteral stones (p<0.001).
ual. Some times, these stones remain asymptomatic and are
identified on routine assessment.1Majority of patients with
larger (>10mm) ureteral stones require intervention. Medical
expulsive therapy to facilitate passage of ureteral stones is
generally not considered as an option for larger ureteral
stones. Most of these are subjected to endourological man-
agement. Selection of treatment is based upon factors such as
size, location, availability of fully equipped endourological
setup, and patients’ preference.
Improvements in ureteroscopic technology have enabled
retrograde ureteroscopy (URS) to become the most frequently
performed intervention for larger ureteral stones. Shock wave
lithotripsy (SWL) still plays an important role for many ure-
teral calculi, particularly the smaller ones,2–3and the addition
of ante grade URS and laparoscopic ureterolithotomy rounds
out the treatment options for large and=or impacted stones.
often considered the worst pain suffered by an individ-
Open ureterolithotomy is no longer considered as a valid
option in a well-equipped endourological center.4
nonrandomized study that SWL and retrograde URS to be
equally efficacious for 10–15mm ureteral stones; however,
they noted a longer period to achieve stone clearance in SWL
group. Tuncet al6notedthatURS usingpneumatic lithotripsy
should be used as the first-line treatment rather than SWL for
stones larger than 10mm.
Management of larger stones is often complicated by
presence of obstruction, infection, or impaction. The AUA
19977and European Association of Urology and American
Urological Association 20078guidelines on ureteral stone
provide a reference point for management strategies. In
1997, the AUA Nephrolithiasis Clinical Guideline Panel re-
commended SWL or URS for >1cm proximal ureteral stones;
for middle ureteral stones, due to the limitations of SWL,
ureteroscopic management is considered as a primary
modality; for management of distal ureteral stones, URS
is uniformly associated with high success rates and low
Department of Surgery, Aga Khan University, Karachi, Pakistan.
JOURNAL OF ENDOUROLOGY
Volume 23, Number 4, April 2009
ª Mary Ann Liebert, Inc.
complication rates. In the current work we have evaluated
outcome of not only stone-free (SF) rate but also efficiency
quotient (EQ)9,10and the safety of URS for larger stones at all
locations in the ureter for stones >10mm, size for which SWL
is not considered as first line.
Patients and Methods
From January 2000 to June 2007, 344 patients with ureteral
stones requiring ureteroscopic fragmentation were enrolled
in the study. However, 79 patients were excluded from fur-
ther evaluation. The inclusion criteria were age >14 years and
>30mm2isolated ureteral stone diagnosed on intravenous
CT along with KUB. Patients with the coexistence of a kidney
stone and post-SWL steinstrasse were excluded. Additional
functional studies, like radioisotope scans, were performed at
thediscretionoftheprimary urologist if there is concern about
thefunctional statusoftherenalunit. Preoperative assessment
included complete clinical evaluation; laboratory work-up
and culture. The stone size was measured on a plain KUB in
twodimensions, thestonelengthandwidth.The stone surface
area is thus calculated using the formula3:
All patients underwent URS under general anesthesia with
an 8F and 7F semirigid ureteroscopes (Wolf?, Knittlingen,
Germany) and a 5F working channel or 6.4F endoscope
(Olympus?, Hachioji-shi, Tokyo, Japan). Access to the stone
was made after placing 0.038-inch floppy-tip guide wire, over
which ureteroscope was introduced. Need for intramural
ureter dilatation was at the discretion of the urologist. Dila-
tation was done with either serial metal dilators or balloon
dilator. Lithotripsy was then performed with the Swiss Litho-
clast with 300kPa pressure with either 0.8 or 1.0mm probe.
Stones were fragmented to *2–3mm particles, and removed;
smaller fragments were allowed to pass spontaneously. After
completion of the procedure, a 5F ureteral catheter (cut tip)
was left in place for 24 hours.11In patients with residual
stone, incomplete fragmentation, significant mucosal edema,
or ureteral trauma, a Double-J stent was placed. The stent is
subsequently removed as a day procedure under local anes-
thesia either when the patient is declared SF or when there is
insignificant (<3mm) stone burden.
KUB obtained after 24–48 hours to exclude migration and
another at 2 weeks and 3 months to asses the SF rate. Patients
belonged to six different attending urologists with separate
operating room days and consulting clinic timings, and pa-
tients are called with first KUB within 48 hours of the proce-
dure and subsequently after 2 weeks and at 3 months for the
one who fails to clear. The time to SF was noted as days from
the procedure to the imaging evidence of SF status. EQ was
calculated using a standard formula, taking into consider-
ations the retreatment rate and ancillary procedures per-
formed. Stone migration was defined as stone retropulsion
back to the kidney as in the case of proximal ureteral stone, or
migrated from distal to middle or from middle to proximal
and not possible to remove by URS. Migration was deter-
mined from the 24–48 hours KUB and the SF rate in 2 weeks
and 3 months postoperatively. All cases of migration were
initially treated expectantly. In case of larger fragments or
failed expectant management, it is treated by placement of
Double-J stent, URS in 2–3 weeks, or adjuvant extracorporeal
SWL after 2 weeks. During URS, for prevention of stone mi-
gration either a basket or instilled 2% lignocaine jell was
used.12,13Residual stones were treated either by re-URS or by
SWL if the trial of conservative treatment fails or if there is a
significant stone burden or patient is symptomatic.
Cross tabulation was the analysis used to compare the
migration and SF rates in the two groups. The independent
t test was used to compare the mean stone size, operative
time, and patient age.
details and stone-related data are detailed in Table 1. Mean
stone surface area was 75.5?13.2 (30–310mm2), 76% had
stone 30–140mm2, whereas 24% had >141mm2stone. The
mean stone clearance at 24–48 hours was 45%, 50%, and 87%,
at 2 weeks 47%, 51%, and 89%, and at 3 months 58.9%, 52.9%,
and 91.9% for lower, middle, and upper ureteral stones, re-
spectively. The results were statistically significantly different
for lowerand middle versusupper ureteral stones (p<0.001).
At 3-month follow-up the overall SF rate, by single session of
URS, was 74% and EQ 59.2%. Impact of stone site and size
indicated that upper and middle ureteral stones (as a group)
and also there is a significant difference in the clearance of 30–
140mm2versus >141mm2stones (p<0.003) (Table 2).
The mean preoperative serum creatinine was 1.56?0.52
(1.0–3.6mg=dL). Twelve (4.5%) patients had pre-URS ancil-
lary procedures: 2 cases of Double-J stents and 10 who had a
percutaneous nephrostomy tube placement. The impact of
ancillary procedures on the stone clearance rate was assessed
in a univariate analysis, and we observed no significant dif-
ference in the SF rate in the group with or without pre-URS
ancillary procedures (Table 3). The impact of mode admis-
sion, that is, day case versus in patient, on SF rate also indi-
cated a statistically insignificant difference (Table 3).
Table 1. Demographic and Stone-Related Parameters
Age, years: median?SD (range)
Mode of admission
Day care (elective)
In patient (emergent)
Stone site in the ureter
IVU¼intravenous urogram; CT¼computed tomography; CT
KUB¼noncontrast enhanced CT; KUB¼kidney, ureter, and bladder
620ATHER ET AL.
In 82%, 12%, and 6% of patients, 8F, 7F, and 6.4F uretero-
scopes were used, respectively. The mean operative time was
was donein 55% patients. In 52% and3%, serial metal dilators
and balloon dilator were used, respectively. Stone or frag-
ment migration was noted in 13% cases, on a 24-hour post-
procedure X-ray. The impact of various stone prevention
methods, thatis,basketorjell instillation, wasnot analyzedas
the practice was not uniform and was at the discretion of the
urologist. After completion of the procedure, 92% patients
had a stent left in place. In 54% Double-J stent was placed,
whereas a 5F ureteral catheter was left in place for 24 hours in
38%. Indication of Double-J stenting included significant
mucosal edema, tight ureter, and mucosal injury in 85%, 8%,
and 7%, respectively.
Most patients with ureteral stones >10mm will require
surgical treatment. The medical expulsive therapy, using ei-
ther a-antagonists or calcium channel blockers, augments the
stone expulsion rate compared to standard therapy for mod-
erately sized (<10mm) distal ureteral stones. For patients
requiring surgical treatment, the European Association of
Urology and American Urological Association guidelines
suggest7,8that both SWL and URS be discussed as initial
treatment options for majority of the cases. Regardless of the
availability of equipment and physician’s experience, the
discussion should include SF rates, anesthesia requirements,
need foradditionalprocedures, andassociatedcomplications.
Patients should be informed that URS is associated with a
better chance of becoming SF with a single procedure, but has
higher complication rates.7,8
Extracorporeal SWL is the least invasive treatment, but its
success rate is decreased for large impacted upper ureteral
calculi. In a comparative analysis of ureterorenoscopic hol-
mium:YAG laser lithotripsy with SWL for large impacted
proximal ureteral stones, Wu and colleagues14noted a sig-
nificant (p<0.003) difference in the SF rate and EQ of URS
(92% and 0.59) versus 61% and 0.53, respectively. Ziaee and
colleagues5in a comparative study of SWL and URS for 10–
15mm stones noted an SF rate of 72.5% for URS 78.6% for
SWL. Our results are comparable as we noted an overall SF of
74%, whereas for lower ureteral stones it was 92%. Segura
et al7noted in the 1997 panel summary that the SF for URS
and SWL was 72% and 44%, respectively, for proximal ure-
teral stones >1cm. In randomized as well as in other com-
parative studies, the retreatment rates were generally higher
for SWL than for URS. Recently, though Tiselius3noted high
(97.1%) SF rates for patients treated with SWL, the average
number of SWL sessions needed was 1.31. For the proximal,
middle, and distal ureter, one SWL session was sufficient in
73.1%, 66.7%, and 83.2% of patients, respectively. Compared
with patients sufficiently treated with one session, the stone
size was significantly larger in those requiring two (p<0.01),
three (p<0.01), or more than four sessions (p<0.01).
Advances in ureteroscopic technology with the introduc-
tion of small caliber semirigid and pneumatic and holmi-
um:YAG laser have improved SF rates after URS while
decreasing the risk of complications. SWL has comparable
Overall, the success rate increased to 77% after3treatments
compared with 76% after two treatments. Upper and mid
ureter SF rates were significantly higher than those in the
lower ureter after initial treatment. Success rate was also
greater for smaller stones (10mm or less v 11–20mm was 74%
v 43%; p<0.001).15The AUA Guidelines Panel7reported its
recommendations for the treatment of ureteral stones. Al-
though this report was clear in its recommendations of SWL
for the treatment of small ureteral calculi, it was less clear for
the large (>1cm) upper ureteral stones.
Djaladat and colleagues17have recently noted in a ran-
domized study that short-term ureteral catheterization in
uncomplicated URS and lithotripsy has a role in reducing
colic after discharge. We used both self-retaining Double-J
ureteral stents and open-end ureteral catheter. The impact of
these two was in relieving postprocedure colic, and compli-
cations were not specifically analyzed in this study.
There are currently several devices for intracorporeal
lithotripsy. With the help of electrohydraulic, ultrasonic,
pneumatic, or laser lithotripters, treatment of ureteral stones
has been achieved with very high success rates.18,19There
are several intracorporeal lithotripsy alternatives, such as
electrohydraulic lithotripsy, ultrasonic lithotripsy, pneumatic
lithotripsy, and holmium laser lithotripsy. Among these
treatment options we use pneumatic lithotripsy successfully
since 1995 for ureteral stone treatment. According to the lit-
higher than 90%.18–20Jeon et al21in a comparative study of
laser and pneumatic lithotripsy noted that holmium:YAG
lithotripsy was associated with shorter operation time and
Table 2. Relationship of Stone-Free Rate
and Efficiency Quotient with Stone Size
and Stone Location
SF rateEQ p-Value
Stone surface area
SF¼stone free; EQ¼efficiency quotient.
Table 3. Impact of Pre-Ureteroscopy Ancillary
Procedures and Mode of Admission
on Stone Clearance
n (%) SF ratep-Valuea
Double-J ureteral stent
No ancillary procedure
Mode of admission
aFischer exact test.
SF¼stone free; PCN¼percutaneous nephrostomy.
URETEROSCOPY IS SAFE AND EFFICIENT FOR >30 MM2STONE 621
postoperative hospitalization period. Their data also sug-
gested that holmium:YAG lithotripsy was safe and more ef-
fective than Lithoclast lithotripsy in the aspect of immediate
SF rate. Bapat and colleagues22in a comparative analysis of
laser and pneumatic lithotripsy for ureteral stones noted that
the fragmentation rates of holmium laser–assisted URS were
significantly better in the upper ureter. The complications and
the need for auxiliary procedures were significantly less for
holmium laser–assisted URS than for pneumatic lithotripsy.
The lower success rate achieved in the mid and proximal
ureter in our series is perhaps related to the use of semirigid
ureteroscope and pneumatic lithotripsy.
While SWL is generally accepted as a first-line treatment
option for ureteral calculi because of its noninvasive nature,
lithotripsy has higher success rates and seems to be good al-
ternative in patients in whom SWL is unsuccessful. In our
opinion, because of its early stone clearance advantage and
high success rates, pneumatic lithotripsy could be considered
as a first-line treatment modality in patients who need early
stone removal due to long-term impaction or obstruction.
However, prospective randomized studies are required to
clearly determine the optimal treatment for large (>1cm)
be offered a choice between SWL and URS based on current
data. Further, issues of cost effectiveness, physician expertise,
and available equipment must be considered.
No competing financial interests exist.
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Address reprint requests to:
M. Hammad Ather, M.D., FCPS (Urol), FEBU
Department of Surgery
Aga Khan University
P.O. Box 3500, Stadium Road
KUB¼kidney, ureter, and bladder radiograph
SWL¼shock wave lithotripsy
622ATHER ET AL.