Abstract
Backgrounds:
Mini-percutaneous nephrolithotomy (M-PCNL) and retrograde intrarenal surgery (RIRS) are commonly used methods for the treatment of kidney stones. The aim of our study is to compare the effectiveness and safety of M-PCNL and RIRS for the treatment of renal pelvic stones with a diameter of 2–3 cm.
Materials and Methods:
The study included 250 patients, who underwent surgery for renal pelvic stones. M-PCNL and RIRS were performed on 130 and 120 patients, respectively. Age, gender, body mass index of the patients, stone size, the side of surgery, operative times, history of extracorporeal shock-wave lithotripsy, Hounsfield unit (HU) values, the length of hospital stay, stone-free rate (SFR), complication rates according to the modified Clavien system, postoperative hemoglobin loss, postoperative transfusion rates, postoperative narcotic analgesic use, and the number of secondary interventions were recorded. SFR in the postoperative first and third months were calculated. A chi-square test, Student's t-test, and the Wilcoxon test were used for statistical analyses.
Results:
No statistically significant differences were found in the demographic data, stone size, complication rates defined according to the modified Clavien system, HU values, and postoperative transfusion rates between the patient groups (P > .05). The success rate was statistically significantly higher regarding the postoperative first-month SFR in the M-PCNL group (P < .05). The postoperative third-month SFR after secondary interventions were similar between the groups. The examination of the postoperative hemoglobin loss and narcotic analgesic use and the length of hospital stay revealed superior results in the RIRS group (P < .05).
Conclusion:
M-PCNL and RIRS are effective and safe methods for the treatment of renal pelvic stones. M-PCNL is advantageous because of high SFR in the postoperative first month and the low need for secondary interventions, whereas RIRS has been found more advantageous in terms of the length of hospital stay, use of narcotic analgesics, and postoperative hemoglobin loss. Further studies on patients with multiple caliceal stones and on patients with a greater stone burden are needed.
Introduction
Kidney stones are one of the most common diseases encountered in daily urology practice. Several different treatment alternatives are available according to the location, size, and structure of stones. 1 According to the European Association of Urology (EAU) guideline, extracorporeal shock-wave lithotripsy (ESWL) and retrograde intrarenal surgery (RIRS) are recommended as the first-line treatment methods for stones <2 cm. For stones >2 cm, percutaneous nephrolithotomy (PCNL) is the first-line surgical method recommended in the EAU guideline. 2
The main goal in stone surgery is to achieve maximum stone-free rate (SFR) through the use of a minimally invasive method. Technological developments have led to significant advances in any surgical method throughout recent years. The improvements in laser systems and imaging systems in RIRS have enabled shorter operative times, thus allowing for the use of the RIRS technique for the treatment of larger stones. 3 In an attempt to decrease complications associated with PCNL, new methods have been developed through reductions in tract size. The procedures with tract sizes of 14–22F are called mini-PCNL (M-PCNL), 4 whereas the procedures with tract sizes of 10–14F are called supermini-PCNL. 5 Supermini-PCNL and especially M-PCNL have become commonly used in both children and adults although neither procedure has been included in guidelines, yet. 5
There are many studies showing that both RIRS and M-PCNL can be easily performed for the treatment of stones >2 cm.6,7 The selected method for the treatment of 2–3 cm stones may vary depending on the surgeon's discretion.6,7 Our aim in this study was to investigate the efficacy and safety of M-PCNL and RIRS techniques for the treatment of renal pelvic stones with a diameter of 2–3 cm.
Materials and Methods
This study was carried out with the Okmeydani Training and Research Hospital Ethics Committee's approval dated 16.04.2019 and numbered 1234.
Patients
Six hundred twenty-eight patients; who underwent surgery for kidney stones in our clinic in the period between December 2016 and October 2020, were retrospectively screened. Of these patients, 250 with 2–3 cm renal pelvic stones were included in the study. M-PCNL and RIRS were performed on 130 and 120 of these 250 patients, respectively. For the treatment of patients; RIRS was used until November 2018 and M-PCNL was started to be used after implementation in our clinic in November 2018. Patients; who underwent surgery because of kidney stones, who had congenital kidney anomalies or caliceal stones, and who underwent a second session of RIRS due to failures of gaining ureteral access were not included in the study.
Complete blood counts, routine biochemistry and coagulation tests, electrocardiography, posterior–anterior chest radiography, and urine culture tests were performed for the study patients. Antibiotic therapy was administered to patients with positive urine culture test results. Preoperative noncontrast computed tomography (NCCT) images of the patients were acquired. Kidney, ureter, and bladder (KUB) X-rays of all study patients were evaluated on the first postoperative day. The second evaluation of the patients was performed at the end of the postoperative fourth week. Patients with opaque stones were evaluated with KUB, and patients with nonopaque stones were evaluated through an ultrasound examination. Double-J stents of the stone-free patients were removed under local anesthesia. The patients who were not stone free underwent secondary procedures. Factors such as the hardness of the stone, anticoagulant use by the patient, and the history of preoperative ESWL were evaluated in patients who underwent RIRS. ESWL was performed for eligible patients. RIRS was performed as a secondary procedure for patients, who were not eligible for ESWL. ESWL was performed for patients, who underwent M-PCNL but who could not achieve stone-free status. NCCT was performed in the postoperative third month to calculate final SFRs. Double-J stents were placed in all patients during the operation.
Patients' age, gender, body mass index, stone size, the side of surgery, history of ESWL, Hounsfield unit (HU) values, the length of hospital stay, SFRs, complication rates according to the modified Clavien system, postoperative hemoglobin loss, postoperative transfusion rates and narcotic analgesic use, and the number of secondary interventions were recorded. All patients underwent general anesthesia. All operations were performed by the same surgeon.
Mini-percutaneous nephrolithotomy
Cystoscopy was performed at the beginning of the operation. A 6F ureteral catheter was placed into the ureter on the operation side over the guidewire. The patients were placed in the prone position. Contrast material was administered to the kidney and 18-gauge Chiba needles were used to achieve renal access. Dilation was performed using fascial dilators. An 18F Amplatz sheath was placed in the kidney. Renal access was gained through the Amplatz sheath using a Storz nephroscope (Karl Storz, Tuttlingen, Germany) device. A Ho-YAG (Quanta 30 W) device and a 1000-μm laser fiber were used to dust kidney stones. Stones were removed using 4F forceps. A nephrostomy tube was placed in 30 patients with prolonged operative time and a potential to bleed. Double-J stents were placed in all patients.
Retrograde intrarenal surgery
First, ureteral access was gained on the side of surgery using a Storz 8F/9.8F rigid uretero-renoscope. A guidewire was progressed to the kidney. A 10–12F ureteral access sheath was progressed over the guidewire. The kidney was accessed through the sheath using a Storz Flex X2 (Karl Storz, Tuttlingen) device. Kidney stones were fragmented using a Ho-YAG (Quanta 30 W) device and a 273-μm laser fiber. A Double-J stent was placed in all patients at the end of the operation. Direct access was performed for 24 patients in whom the intraoperative placement of the ureteral access sheath was not successful.
Statistical analysis
A chi-square test was used for the comparison of the two study groups. The Student's t-test was used for testing continuous variables conforming to a normal distribution. The Wilcoxon test was used to test continuous variables that did not conform to a normal distribution. A P value of <.05 was considered statistically significant. The SPSS 20.0 software was used for statistical analyses.
Results
The demographic data of the patients, characteristics of kidney stones, the side of surgery, and the history of ESWL have been summarized in Table 1. The comparison of the two study groups revealed no statistically significant differences in the demographic data, stone characteristics, side of surgery, HU values, and ESWL history (P > .05).
Demographic Data and Stone Characteristics
BMI, body mass index; CT, computed tomography; ESWL, extracorporeal shock-wave lithotripsy; HU, Hounsfield unit; M-PCNL, mini-percutaneous nephrolithotomy; RIRS, retrograde intrarenal surgery; SD, standard deviation.
The comparison of the operative data between the patient groups revealed no statistically significant differences in the operative time, postoperative transfusion rates, and postoperative complications defined according to the Clavien system (P > .05). The postoperative first-month SFRs were 115 (88%) and 93 (78%) in the M-PCNL and RIRS groups, respectively. The first-month SFR was found to be superior with a statistically significant difference in the M-PCNL group compared with the RIRS group (P < .05). Similar results were found when SFRs were examined after the secondary interventions in the postoperative third month (P > .05). The lengths of hospital stay were 2.92 ± 0.32 and 1.84 ± 0.28 for the M-PCNL and RIRS groups, respectively. The length of hospital stay was statistically significantly shorter in the RIRS group compared with the M-PCNL group (P < .05). The postoperative hemoglobin loss values were 1.842 ± 0.692 and 0.934 ± 0.348 for the M-PCNL and RIRS groups, respectively. The postoperative hemoglobin loss was statistically significantly less in the RIRS group compared with the M-PCNL group (P < .05). The RIRS group was found to be more advantageous in terms of postoperative narcotic analgesic use (P < .05). There were no life-threatening complications (Clavien system grade 4–5) in any of the study groups. Only 2 patients in the M-PCNL group underwent angioembolization due to bleeding. Postoperative ESWL was performed for 15 patients in the M-PCNL group and 15 patients in the RIRS group. Furthermore, 12 patients in the RIRS group underwent a second session of RIRS. The operative data of the patients have been summarized in Table 2.
Operative Data
M-PCNL, mini-percutaneous nephrolithotomy; RIRS, retrograde intrarenal surgery; SD, standard deviation.
Discussion
Individuals with kidney stone disease constitute a major patient population presenting to urology clinics, especially in endemic regions, including our country. PCNL and RIRS are among the most common operations performed in urology. Therefore, reaching the highest SFR with the least invasive method is the biggest goal of these operations. M-PCNL and RIRS continue to gain more importance day by day because PCNL is a surgical method associated with major complications, including intraoperative bleeding and urinary extravasation. 8
Many studies are available comparing the M-PCNL and RIRS techniques. The majority of such studies have examined the efficacy and safety of these two techniques for the treatment of lower-pole renal stones. 9 In the systematic review and meta-analysis by Cabrera et al., the complication rates and length of hospital stay were found similar through the M-PCNL and RIRS techniques, but SFR was reported to be better for the M-PCNL technique than that found for RIRS. 10 The study by Mao-Mao Li et al., investigating the M-PCNL and RIRS techniques for the treatment of lower pole stones with diameters between 15 and 25 mm, found similar SFRs achieved by any of these methods contrary to the study by Cabrera et al.10,11
Similar to our study, the meta-analysis by Jiang et al. on 1317 patients evaluated RIRS and M-PCNL methods for the treatment of upper urinary tract stones, demonstrating that SFRs with M-PCNL at the end of the first month were superior to those obtained by RIRS. Again, similar to our study, Jiang et al. reported that RIRS was more advantageous in terms of the length of hospital stay and postoperative hemoglobin loss. 12 Similar results have been reported in many other systematic reviews.13,14 Those systematic reviews mostly included stones >10 mm.
Similar to our study, Pan et al. compared the M-PCNL and RIRS methods for the treatment of kidney stones with diameters between 2 and 3 cm. Pan et al. found that postoperative SFRs in the first month were higher in the M-PCNL group similar to the results of our study. Also, Pan et al. reported that RIRS was advantageous in terms of the length of hospital stay and postoperative hemoglobin loss. However, that study reported a longer operative time in the RIRS group contrary to our study results. Furthermore, Pan et al. found out that M-PCNL was more costly in terms of operative costs. 15
Zhao et al. developed a different perspective for the comparison of the M-PCNL and RIRS techniques in their study. The overall results of that study are similar to our study results in terms of the length of hospital stay, the superiority of the RIRS group regarding the decreased hemoglobin values, and the superiority of initial SFR in the M-PCNL group. However, contrary to our study results, the M-PCNL group was found superior in terms of SFR in the third month after secondary interventions. Zhao et al. identified three different risk factors in the RIRS group, including the presence of stones in the lower calyx, severe hydronephrosis, and the presence of stones in multiple calyces. Zhao et al. demonstrated that the success of RIRS was potentiated when none or only one of these risk factors were present. 16 We can explain the differences in SFRs obtained in the postoperative third month in our study based on our patient population because low-risk patients having isolated renal pelvic stones were included in the study.
There are various limitations of our study. Since our study has a retrospective design, the data may be biased. The number of patients included in the study is limited because the intraoperative fluoroscopy times were not available for most of the patients reviewed. Concerning the standardization, renal pelvic stones that were operated on for the first time were included in the study. However, previously operated patients and patients with a greater stone burden should also be investigated.
Conclusion
M-PCNL and RIRS are safe and effective two methods for the treatment of renal pelvis stones with diameters between 2 and 3 cm. M-PCNL is more advantageous than RIRS because of high SFRs in the postoperative first month and a lower need for secondary interventions, whereas RIRS is more advantageous than M-PCNL because of its shorter operative times, less hemoglobin loss postoperatively, and less postoperative narcotic analgesic use. Further prospective studies on larger patient series are needed.
Footnotes
Authors' Contributions
Conception and design, acquisition of data, analysis and interpretation of data, and final approval of the completed article were by M.E. and M.B.
Disclosure Statement
No competing financial interests exist.
Funding Information
No research support or funding was received in connection with this study. The authors have no significant affiliation or involvement, either direct or indirect, with any organization or entity with a direct financial interest in the subject matter or materials discussed.