Comparison of Retrograde Intrarenal Surgery and Percutaneous Nephrolithotomy Methods in Treatment of Upper Calyceal Stones of 10

Abstract

Objective:

To compare the success and complication rates and advantages and disadvantages of retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PNL) methods for the upper calyceal renal stones between 10 and 20 mm.

Materials and Methods:

The files of 124 patients who had upper calyceal renal stones in diameter 10–20 mm were analyzed retrospectively. Sixty-one patients were randomized as Group 1 and 63 as Group 2. The parameters as success and complication rates, fluoroscopy and operation times, preoperative and postoperative hemogram (Hb) levels, and need of blood transfusion were saved and then groups compared. Complication rates and need of second procedure numbers between groups were evaluated according to modified Clavien classification.

Results:

Demographic features and success and complication rates between groups were similar. Hospitalization time was 1.0 ± 0.1 day for Group 1 and 2.3 ± 1.4 days for Group 2. When preoperative and postoperative Hb difference was evaluated, 0.1 ± 0.3 mg/dL decrease was noticed for Group 1 and 1.6 ± 0.8 mg/dL decrease for Group 2. Mean operation time for Group 1 was 53.6 ± 15.1 minutes and mean fluoroscopy time was 20.1 ± 8.9 seconds for Group 1; for Group 2, these values were 67.8 ± 16.2 minutes and 53 ± 15.0 seconds, respectively. As a result, mean operation time and fluoroscopy time, hospitalization time, and Hb decrease levels were found less and as statistically significant for Group 1.

Conclusion:

RIRS and PNL methods both have the same success and complication rates for upper calyceal renal stones between 10 and 20 mm. However, we think that RIRS method should be preferred for suitable patients because it is a more noninvasive method and has advantages of some operation parameters over PNL.

Introduction

Urinary stones are one of the most common causes of patients' presentation to urology polyclinics. Until 30 years ago, these patients could be treated with open surgery and healing process might be prolonged. Today, in parallel with technological advancement, urinary system stones at every level, which have indications for treatment, can be accessed and treated with more noninvasive methods. While percutaneous nephrolithotomy (PNL), retrograde intrarenal surgery (RIRS), and extracorporeal shock wave lithotripsy (ESWL) are recommended in the treatment of the stones between 10 and 20 mm in The European Association of Urology (EAU) guidelines, there is no definite consensus on the point of priority.¹ Limited studies in the literature have been performed about the treatment of isolated upper calyceal stones of 10–20 mm without a consensus achieved.

The objective of this study was to compare success and complications as well as advantages and disadvantages of PNL and RIRS methods that we used in the upper calyceal kidney stones of 10–20 mm.

Materials and Methods

Files of the patients who underwent PNL and RIRS due to kidney stones in the urology clinic of our hospital between January 2008 and December 2014 were retrospectively studied with the approval received from the review board. The study included patients with kidney stones with the long diameter of 10–20 mm and localized in the upper calyx. Patients with a solitary kidney, ureteropelvic junction obstruction, horseshoe kidney, and pelvic renal anomaly, and those who had previous open or percutaneous surgery were excluded from the study. Sixty-one patients who underwent RIRS were assigned to Group 1 and 63 patients who had undergone PNL to Group 2.

Parameters such as the success and complication rates; scope, operation, and hospitalization times; preoperative and postoperative hemogram (Hb) values; and the need for blood transfusion were recorded end compared between the groups. Between groups evaluation of complications and additional procedure requirement was carried out according to the modified Clavien classification.

Preoperative complete blood count, serum urea and creatinine values, hemorrhage and coagulation profiles, and complete urine analysis and urine cultures were studied in all patients. Diagnosis and treatment of renal stones were planned to utilize noncontrast computed tomography, intravenous pyelography, urinary ultrasonography (USG), and other imaging modalities if deemed necessary. When the size of the stones was compared, surface areas that were calculated using the formula of width × length × pi × 0.25 were considered. The stone size was obtained by measurement of the longest two diameters. In the patients who were scheduled for surgical intervention and were on anticoagulant drugs, medications were discontinued 7–10 days before the operation by consulting the relevant department. However, 2 patients in the RIRS group in whom discontinuation of anticoagulant therapy would pose a risk were operated without stopping anticoagulant therapy and included in the study.

Patients were checked through direct urinary system graphy (DUSG) or through USG, if necessary on the first postoperative day. Full stone-free status of the patients was assessed with NCCT ordered after 4–6 weeks. The stone fragments that were asymptomatic, smaller than 4 mm, caused no obstruction, and not infected were considered clinically insignificant residual fragments (CIRFs). The method was accepted as successful in patients who were stone free or have CIRFs after the operation.

Technique

Patients in both groups were administered third-generation cephalosporin 1 hour before the operation and the surgery was performed under general anesthesia. In RIRS methods, cystoscopy was carried out in the modified dorsal lithotomy position and a 0.035-inch safety guidewire was inserted into the ureter that will be intervened. Following insertion of the first guidewire, the bladder was drained. The ureter was then introduced with a semirigid ureterorenoscope and diagnostic ureterorenoscopy (URS) was performed with advancing as far as possible toward proximal. When access could not be provided due to obstruction in the ureteral orifice or other areas of the ureter, a Double-J (DJ) stent was inserted and the operation was done after 2–3 weeks of passive dilatation.

After URS, 9.5/11.5 Fr ureteral access sheath was inserted at a proper ureteral level through the guidewire. A flexible URS (FURS) (Flex-X2; Karl Storz, Tuttlingen, Germany) was advanced through it and following observation of the stone, lithotripsy was applied with a 272 μm holmium laser probe (Ho-YAG Laser; Dornier MedTech, Munich, Germany). Fluoroscopic control was made when all the stones were considered to be fragmented. The fragments were removed with stone forceps as much as possible. The procedure was terminated with insertion of DJ stents and 16F foley urethral catheters in all patients. Patients were controlled on the first postoperative day through DUSG or USG after removal of the urethral catheters. DJ stents of the patients who were not scheduled for additional interventions were removed after 1–2 weeks.

In PNL technique, patients were given lithotomy position and a 5–6 Fr 20 open-ended ureteral catheter was inserted into the side that will be intervened with the help of a cystoscope. Whether the ureteral catheter was inserted in the collecting system was checked under fluoroscopic guidance. A 16 Fr foley ureteral catheter was inserted and fixed to the ureteral probe with suturing. Head and neck of the patient were taken into prone position with careful attention given to the anesthesia side. The points exposed to pressure in the patient in prone position were supported with silicon cushions. After the operational site was cleaned with an antiseptic solution, the patient, camera, and C-arm fluoroscopy unit were covered with a sterile percutaneous drape set. The ureteral catheter was taken out through a small hole on the percutaneous drape.

Radiopaque substance (diluted with approximately one to four serum physiologic) was given under C-arm fluoroscopic vision and the pelvicalyceal system was opacified. The target calyx was determined and accessed under fluoroscopy. Then, a 0.035-inch, J-tip guidewire needle was sent into the collecting system through it. Amplatz dilators were dilated up to 30 Fr through the parenchymal guidewire and a 30 Fr operating sheath was inserted into the collecting system. A 26 Fr nephroscope (Karl Storz^®) was advanced through the operating sheath and the pelvicalyceal system was observed. The stones detected in the pelvicalyceal system were fragmented with a pneumatic lithotripter (Lithoclast; EMS, Nyon, Switzerland) and extracted using forceps. Then “through–through access” was attempted, if possible. After the stones were cleaned, the procedure was terminated with the insertion of an appropriate nephrostomy catheter.

Patients developing perioperative hemorrhage were administered blood transfusion following perioperative hematocrit and hemodynamic assessment by anesthesia department. Blood transfusion was made to the patients deemed appropriate among those who had undergone postoperative complete blood count. The nephrostomy tube was removed on postoperative day 1 in stable patients with no hematuria, visible fragments, after the tube was clamped for 12 hours and no fever, pain, and discharge from around the nephrostomy tube was observed. Those patients who developed renal colic postoperatively had their nephrostomy tube removed after nephrostogram with or without insertion of antegrade or retrograde double J catheters. DJ catheters were inserted in patients whose urine from the nephrostomy tract was not stopped within 24 hours after the nephrostomy tube was removed. Patients without complications developed were discharged on the second postoperative day.

Statistical analysis

Statistical analysis of data was performed using SPSS 21.0 software. Descriptive statistics are expressed as mean ± standard deviation for normally distributed variables, median (minimum–maximum) for nonnormally distributed variables, and the number of cases and percentage for nominal variables. Since the number of the groups was two, the significance of the difference between the groups was studied with t-test in terms of mean values and Mann–Whitney test in terms of median values. Nominal variables were evaluated with Pearson, chi-square, or Fischer's exact tests.

Results

When demographics of the groups were compared, the mean age was found as 46.4 ± 11.2 in Group 1 and 47.4 ± 11.6 in Group 2. Looking at the stone load, mean stone size was found as 139.8 ± 36.9 mm² in Group 1 and 138.3 ± 30.3 mm² in Group 2. No statistically significant difference was found between both groups in terms of demographic characteristics. Demographics of the patients are given in Table 1.

Table 1.

Comparison of Preoperative Demographic Patient Data

Variables	Group 1 (n = 61)	Group 2 (n = 63)	P value
Sex
Male (%)	62.3 (n = 38)	49.2 (n = 31)	.142
Female (%)	37.7 (n = 23)	50.8 (n = 32)
Stone site (%)
Right	49.2 (n = 30)	52.4 (n = 33)	.722
Left	50.8 (n = 31)	47.6 (n = 30)
Stone burden (mm²)	139.8 ± 36.9	138.3 ± 30.3	.895

While 27 patients in Group 1 reached full stone-free status, CIRF was found in 33 patients and the technical success was calculated as 98.4% for this group. Upon 1 patient in this group, who developed perforation of the collecting system when inserting the access sheath, DJ stent was inserted, the procedure was terminated, and the method was considered to fail. Later, stonelessness was achieved in this patient by performing RIRS in the second session. Again, 4 patients in Group 1 developed postoperative fever, which was resolved with conservative treatment, and 1 patient developed urinary tract infection, which could be treated with oral antibiotics.

While in Group 2, full stone-free status was obtained in 56 patients and CIRF was found in 4 patients, the technical success of the method was calculated as 95.2%. Among the remaining 3 patients, 1 developed intraoperative perforation of the collecting system, DJ stent was inserted, the operation was ended, and this patient was referred to SWL after discharge. Another patient developed intraoperative hemorrhage and the operation was ended because of the failure to obtain a clear vision. Upon residual fragment being detected on DUSG ordered on the first postoperative day, SWL was planned, but since the fragment passed to the ureter after discharge, the patient admitted to our clinic with renal colic, nausea/vomiting, and hematuria. The patient underwent URS and was treated.

Upon the development of pneumothorax in 1 of 6 patients, who we applied intercostal access, the operation was ended and a chest tube was inserted into the patient. This patient was referred to SWL after discharge. The method was considered to fail for these 3 patients in Group 2, and at their follow-up, these patients did not develop additional complications and could reach stone-free status. In addition, 2 patients in Group 2 showed decreased Hb values at postoperative follow-up and were administered erythrocyte suspension replacement. Again, in 1 patient, there was high fever, which could be resolved with conservative treatment. Because the patient had prolonged drainage from the nephrostomy tract after the nephrostomy ordered on the 2nd postoperative day, DJ stenting was performed on this patient.

Success and complication rates were similar between the two groups; however, complications developed in Group 2 were observed to be of a higher degree according to the Modified Clavien Classification. Modified Clavien Classification of the complications is summarized in Table 2.

Table 2.

Complication Rates According to Modified Clavien Classification

Complication grade	RIRS (n = 61)	PNL (n = 63)	P value
I	4	1
II	1	3
III
A	1	3
B	—	—
IV	—	—
V	—	—
Total	6 (9.8%)	7 (11.1%)	.817

PNL, percutaneous nephrolithotomy; RIRS, retrograde intrarenal surgery.

The groups were compared in terms of operational parameters. Hospitalization duration was found as 1.0 ± 0.1 day in Group 1 and 2.3 ± 1.4 days in Group 2. Hospitalization duration was significantly shorter in Group 1 compared with Group 2 (P < .001). Looking to the difference between preoperative and postoperative Hb values, the mean reduction in Hb was found as 0.1 ± 0.3 mg/dL in Group 1 and 1.6 ± 0.8 mg/dL in Group 2 patients. Reduction in Hb was found to be statistically significantly lower in Group 1 than in Group 2. The mean operational time was found as 53.6 ± 15.1 minutes and the mean fluoroscopy time was found as 20.1 ± 8.9 seconds in Group 1, while these values were found as 67.8 ± 16.2 minutes and 53 ± 15.0 seconds in Group 2, respectively. The mean operation and fluoroscopy times were statistically significantly shorter in Group 1 compared with Group 2. Results of the operational parameters between the groups are given in Table 3.

Table 3.

Operation Outcomes

	Group 1 (n = 61)	Group 2 (n = 63)	P value
Success rate (%)	98.4%	95.2%	.619
Complication rate (%)	9.8%	11.1%	.817
Hb decrease (mg/dL)	0.1 ± 0.3	1.6 ± 0.8	<.001
Hospitalization (day)	1 ± 0.1	2.3 ± 1.4	<.001
Operation time (minute)	53.6 ± 15.1	67.8 ± 16.2	<.001
Flouroscopy time (second)	20.1 ± 8.9	53 ± 15.0	<.001

Hb, hemogram.

Discussion

There is no a definite consensus for the treatment of kidney stones between 10 and 20 mm in the guidelines by the EAU, while SWL or endourological procedures are recommended.¹ However, with the technologic advancements and increased surgical experience, now RIRS seems to become an increasingly preferred treatment option for the treatment of kidney stones with adequate indications. There are only a few isolated studies about RIRS and PNL procedures performed on the upper calyceal stones of the kidney. Cecen et al. performed RIRS on a total of 66 patients with the upper and medium calyceal stones and could obtain stonelessness by 92.4%. Five patients required repeat procedure and full stonelessness could be achieved after the 2nd session of RIRS.² Resorlu and Unsal compared SWL, PNL, and RIRS methods in radiolucent kidney calculi of 1–2 cm and achieved the stone-free status of 87% after a single procedure in 46 patients.³ In their prospective study, Sabnis et al. performed RIRS on a total of 32 patients with kidney stones of 1–2 cm, with 3 being in the upper calyx, and obtained success by 96.88%,⁴ whereas, in the present study, we performed RIRS method on 61 patients with upper calyceal stones and obtained a success rate of 98.4%. We attributed this high success rate we obtained in our study to size of the stones selected, general problems seen in the lower calyceal stones being less frequently encountered in the upper calyceal stones, the device requiring less operation at flexion or deflexion state to access the stone, and all of these providing the operation to be performed with less manipulation and more comfortably.

Although RIRS seems to be a comfortable method for both surgeons and patients, it has several disadvantages such as a high cost and being easily impaired compared to PNL. In addition, disruptions and breaks that can occur in laser probes, nitinol baskets and access sheaths used in RIRS methods are shown among the cost increasing factors.⁵ Somani et al. reported the need for repair of the first FURS which they have used in the procedure performed in their clinic, after the 24th case and a total 11 repair processes for five FURSs during 260 procedures.⁵ Bultitude et al. have used three FURS during 256 procedures that they had performed since 1999 and they have used one device in 85 cases on average.⁶ With increased experience, number of cases per device is also being increased, reducing the cost. Although the first FURS we used was needed to be repaired after the 11th cases, with the increasing experience, repair or change was applied to 16 devices in a total of 2564 procedures.

It is also possible to achieve a high stonelessness rate with PNL method. Looking at the wide series published in the literature, the success rate of this technique differs between 72% and 98% with an acceptable rate of complications. The first wide series in the literature is a study conducted by Segura et al. in 1985 to discuss results of 1000 PNL cases. In the same year, a study by Hasun et al. with 1122 PNL cases found a high success rate as 98%.^7,8 In a study by Akman et al., 6 of 34 patients who had undergone PNL had upper calyceal stones and despite the mean stone size of 270 mm², stone-free status of 91.2% could be obtained in general study population.⁹ In our study, this rate is 95.2%, consistently with the literature.

Considering complication rates, RIRS method may have a lower risk of severe complications compared to PNL method because the devices used are of lower caliber and flexible, and the procedure is performed through direct examination. The incidence of general complications due to RIRS operation varies between 0% and 25%. These complications include fever (2%–28%), prolonged use of antibiotics (4%–5%), sepsis (3%–5%), bleeding (0%–5%), injury of the stone tract, and ureteral injuries.¹⁰

Bleeding is a rarely seen complication with RIRS method.¹⁰ Studies in the literature report minor bleeding by about 4% after the procedure is applied to patients with a bleeding diathesis.¹¹ Turna et al. evaluated bleeding parameters between patients receiving anticoagulants and control subjects, and observed a minor increase in bleeding.¹² Two patients receiving anticoagulants were included in our study and developed no complication related to postoperative bleeding.

Although the majority of complications observed with RIRS are minor complications that can spontaneously be recovered with observation and follow-up, major complications may lead to serious and permanent problems. The most serious complication of this procedure is ureteral avulsion, which is seen by 0%–0.5%.¹³ The rate of complications observed in the RIRS groups in our study was found as 9.8%, consistent with the literature, and no major complication was developed.

While, despite high stonelessness rates with PNL method, complications with this method reach 83% in the literature.¹⁴ These complications include postoperative fever by 0%–32.1%, bleeding requiring transfusion by 0%–20%, urinary extravasation by 7%, and more infrequently collecting system injuries, adjacent organ injuries, thoracic complications, and mortality.^1,15,16

Greater amount of bleeding with PNL method may be attributed to the procedure being a more invasive operation involving a series of dilatations and well-supplied renal parenchyma. Moreover, there is no consensus in the literature about the effect of the type of dilatator used for the tract dilatation during PNL on bleeding.^17–19 We used Amplatz dilatator set in our patients on whom we performed PNL. In addition, some authors state that the upper calyceal orifices increase thoracic complications.^20–22 Netto et al. found that the upper calyceal orifice caused a slight increase in the rate of complications.²¹ Again, in a study by Shilo et al. evaluating PNL patients on whom they approached from different calyces, the upper calyceal approach was found to be at a significantly higher risk in terms of developing complications compared to the lower calyceal approach (21% versus 2%).²²

In this study, 1 patient accessed with the supracostal upper calyceal approach developed pneumothorax and then was stabilized with a chest tube. None of our other patients intervened with supracostal access developed thoracic complications. Furthermore, no major complication was seen in our study, while total complication rate in our patients who had undergone PNL was 11.1%. The low rate of complication might be explained by the number of patients, surgical experience, and relatively smaller size of the stones.

Although studies comparing PNL and RIRS methods in the upper calyceal stones are limited in the literature, in their study, Koyuncu et al. compared these two methods in calyceal stones larger than 2 cm and found a significantly higher amount of reduction in Hb value in the PNL group compared to the RIRS group.²³ In a meta-analysis from the literature, although rates of complications were similar between PNL and RIRS methods, low levels of Hb requiring blood transfusion were found to be significantly higher in the PNL group.²⁴ Similar results were obtained in our study.

PNL method involves a series of procedures such as the need for the proper patient position, establishment and dilatation of an appropriate tract, and insertion of a nephrostomy tube and may require a more close monitorization during the postoperative follow-up period. Some studies in the literature found shorter durations of operation, hospitalization, and fluoroscopy with RIRS method,^9,24,25 although in their study, Koyuncu et al. found no significant difference between both groups in terms of operational time.²³ Whereas, in our study, these durations were found to be statistically significantly shorter in the RIRS group.

Although the number of studies comparing RIRS and PNL for the upper calyceal stones is lacking, there are many for the treatment options of other kidney stones. These studies discussed the success, complications, and safety of different operation methods like PNL, mini-PNL, miniperc, SWL, and RIRS. Ozturk et al. compared SWL, PNL, and RIRS for 10–20 mm lower pole renal calculi and observed 76%, 94%, and 73% success rates and 3% 13%, and 5% complication rates, respectively.²⁶ Kumar et al. compared miniperc, SWL and RIRS for the treatment of stones of same size and location, and found 95.1% stone-free rates in 3 months for miniperc, 73.8% for SWL and 86.1% for RIRS.²⁷

If diameter of the stone increases, success rates were reduced and operation time gets longer for the RIRS group, also more hemoglobin decline noticed for the PNL group.^28–30 In comparison of miniperc and RIRS as minimally invasive methods, operation time, hemoglobin decline, and hospitalization time were similar with high success rates (85.7% and 97%, respectively), but there were more low-grade complications according to the Modified Clavien Classification for the miniperc technique.^31,32

Complicated cases like patients with solitary kidney, ureteropelvic junction obstruction, horseshoe kidney, and pelvic renal anomaly form a challenging part of the kidney stones treatment. Minimally invasive methods may be suitable for these complicated cases. For example Zeng et al. recommended minimally invasive methods like RIRS and mini-PNL for the treatment of renal calculi with a solitary kidney.³³ We did not include patients with complicated cases or prior open or percutaneous operation in our study because these might affect the choice of surgical method of the surgeon or need auxillary procedures and alternate the results.

In conclusion, in this study, we aimed to compare success, safety, as well as advantages and disadvantages of these two methods over each other. Retrospective nature of our study, relatively small number of patients, failure to sufficiently access patient factors (diabetes mellitus, hypertension, body mass index etc.), and lack of the subanalyses and excluded patients with solitary kidney, uretropelvic junction obstruction, horsehoe kidney, pelvic renal anomaly, and those with prior open or percutaneous surgery, may be considered limitations to our study. We thought that we could give a point of view in the treatment of uncomplicated upper calyceal stones However, we believe that this study will be guiding because the studies comparing these two techniques in the upper calyceal stones of 10–20 mm are scarce in the literature. We think that further prospective randomized studies to be performed on this topic will provide a better insight.

Conclusion

There is no definite consensus about the treatment of the upper calyceal stones of 10–20 mm. Although similar results were obtained in the success of treatment with both methods, we believe that RIRS method could be preferred over PNL method in eligible patients due to shorter times of hospitalization, operation and fluoroscopy, noninvasiveness, and less major complications with this method.

Footnotes

Disclosure Statement

No competing financial interests exist.

References

Türk

, Knoll

, Petrik

, Sarica

, Skolarikos

, Straub

, et al., eds. Guidelines on Urolithiasis. European Association of Urology Congress, March 11–15, 2016. Munich: European Association of Urology, 2016.

Cecen

, Karadag

, Demir

, Bagcioglu

, Kocaaslan

, Sofikerim

. Flexible ureterorenoscopy versus extracorporeal shock wave lithotripsy for the treatment of upper/middle calyx kidney stones of 10–20 mm: A retrospective analysis of 174 patients. Springerplus, 2014; 3:557.

Resorlu

, Unsal

. Comparison of percutaneous nephrolithotomy and retrograde flexible nephrolithotripsy for the management of 2–4 cm stones: A matched-pair analysis. BJU Int, 2012; 109:5–6.

Sabnis

, et al. Treating renal calculi 1–2 cm in diameter with minipercutaneous or retrograde intrarenal surgery: A prospective comparative study. BJU Int, 2012; 110:346–349.

Somani

, Robertson

, Kata

. Decreasing the cost of flexible ureterorenoscopic procedures. Urology, 2011; 78:528–530.

Bultitude

, et al. Prolonging the life of the flexible ureterorenoscope. Int J Clin Pract, 2004; 58:756–757.

Segura

, et al. Percutaneous removal of kidney stones: Review of 1,000 cases. J Urol, 1985; 134:1077–1081.

Hasun

, et al. Percutaneous coagulum nephrolithotripsy: A new approach. Br J Urol, 1985; 57:605–609.

Akman

, et al. Comparison of percutaneous nephrolithotomy and retrograde flexible nephrolithotripsy for the management of 2–4 cm stones: A matched-pair analysis. BJU Int, 2012; 109:1384–1389.

10.

Cho

. Current status of flexible ureteroscopy in urology. Korean J Urol, 2015; 56:680–688.

11.

Aboumarzouk

, Somani

, Monga

. Flexible ureteroscopy and holmium: YAG laser lithotripsy for stone disease in patients with bleeding diathesis: A systematic review of the literature. Int Braz J Urol, 2012; 38:298–305.

12.

Turna

, et al. Safety and efficacy of flexible ureterorenoscopy and holmium:YAG lithotripsy for intrarenal stones in anticoagulated cases. J Urol, 2008; 179:1415–1419.

13.

D'Addessi

, Bassi

. Ureterorenoscopy: Avoiding and managing the complications. Urol Int, 2011; 87:251–259.

14.

Michel

, Trojan

, Rassweiler

. Complications in percutaneous nephrolithotomy. Eur Urol, 2007; 51:899–906.

15.

Lee

, et al. Complications of percutaneous nephrolithotomy. AJR Am J Roentgenol, 1987; 148:177–180.

16.

Mousavi-Bahar

, Mehrabi

, Moslemi

. Percutaneous nephrolithotomy complications in 671 consecutive patients: A single-center experience. Urol J, 2011; 8:271–276.

17.

Bucuras

, et al. The Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study: Nephrolithotomy in 189 patients with solitary kidneys. J Endourol, 2012; 26:336–341.

18.

Davidoff

, Bellman

. Influence of technique of percutaneous tract creation on incidence of renal hemorrhage. J Urol, 1997; 157:1229–1231.

19.

Nalbant

, Karakoyunlu

, Yesil

, et al. Comparison of dilation methods in percutaneous nephrolithotomy: Which one is more successful?. J Laparoendosc Adv Surg Tech A, 2016; 26:478–482.

20.

Palnizky

, Halachmi

, Barak

. Pulmonary complications following percutaneous nephrolithotomy: A prospective study. Curr Urol, 2013; 7:113–116.

21.

Netto

Jr. , et al. Comparative study of percutaneous access for staghorn calculi. Urology, 2005; 65:659–662.

22.

Shilo

, et al. [Comparative morbidity for different accesses in percutaneous nephrolithotripsy]. Harefuah, 2006; 145:107–110.

23.

Koyuncu

, et al. Intrarenal surgery vs percutaneous nephrolithotomy in the management of lower pole stones greater than 2 cm. Int Braz J Urol, 2015; 41:245–251.

24.

Zhang

, et al. Retrograde intrarenal surgery versus percutaneous nephrolithotomy versus extracorporeal shockwave lithotripsy for treatment of lower pole renal stones: A meta-analysis and systematic review. J Endourol, 2015; 29:745–759.

25.

Karakoc

, et al. Comparison of retrograde intrarenal surgery and percutaneous nephrolithotomy for the treatment of renal stones greater than 2 cm. Turk J Urol, 2015; 41:73–77.

26.

Ozturk

, et al. Comparison of percutaneous nephrolithotomy, shock wave lithotripsy, and retrograde intrarenal surgery for lower pole renal calculi 10–20 mm. Urol Int, 2013; 91:345–349.

27.

Kumar

, et al. A prospective, randomized comparison of shock wave lithotripsy, retrograde intrarenal surgery and miniperc for treatment of 1 to 2 cm radiolucent lower calyceal renal calculi: A single center experience. J Urol, 2015; 193:160–164.

28.

Jung

, et al. Comparison of retrograde intrarenal surgery versus a single-session percutaneous nephrolithotomy for lower-pole stones with a diameter of 15 to 30 mm: A propensity score-matching study. Korean J Urol, 2015; 57:525–532.

29.

Bryniarski

, et al. A randomized controlled study to analyze the safety and efficacy of percutaneous nephrolithotripsy and retrograde intrarenal surgery in the management of renal stones more than 2 cm in diameter. J Endourol, 2012; 26:52–57.

30.

Bozkurt

, et al. Retrograde intrarenal surgery versus percutaneous nephrolithotomy in the management of lower-pole renal stones with a diameter of 15 to 20 mm. J Endourol, 2011; 25:1131–1135.

31.

Lee

, et al. Mini-percutaneous nephrolithotomy vs retrograde intrarenal surgery for renal stones larger than 10 mm: A prospective randomized controlled trial. Urology, 2015; 86:873–877.

32.

Kiremit

, et al. Contemporary management of medium-sized (10–20 mm) renal stones: A retrospective multicenter observational study. J Endourol, 2015; 29:838–843.

33.

Zeng

, et al. The comparison of minimally invasive percutaneous nephrolithotomy and retrograde intrarenal surgery for stones larger than 2 cm in patients with a solitary kidney: A matched-pair analysis. World J Urol, 2015; 33:1159–1164.

Comparison of Retrograde Intrarenal Surgery and Percutaneous Nephrolithotomy Methods in Treatment of Upper Calyceal Stones of 10–20 mm

Abstract

Abstract

Objective:

Materials and Methods:

Results:

Conclusion:

Introduction

Materials and Methods

Technique

Statistical analysis

Results

Discussion

Conclusion

Footnotes

Disclosure Statement

References