Flexible ureteroscopy, extracorporeal shock wave lithotripsy and mini percutaneous nephrolithotomy for management of lower pole renal hard stones ≤ 2 cm: a prospective randomized study

Abstract

Background

Managing lower pole renal stones presents clinical challenges influenced by various factors such as stone size, location, and density. This study aims to assess the efficacy, safety, and stone-free rates of Flexible Ureteroscopy (FURS), Extracorporeal Shock Wave Lithotripsy (ESWL), and Mini Percutaneous Nephrolithotomy (Mini PCNL) for treating lower pole renal hard stones (< 2 cm).

Methods

A prospective single-centre comparative study was conducted on 414 adult patients with primary lower pole renal hard stones. Patients were evenly distributed into three groups: Flexible Ureteroscopy (FURS) utilizing holmium laser lithotripsy, Extracorporeal Shock Wave Lithotripsy (ESWL), and Mini PCNL employing holmium laser lithotripsy.

Results

Statistically significant differences with P value < 0.001 were observed among groups in stone-free rates, hospital stay, radiation exposure, operative duration, auxiliary treatments, and overall cost. No statistically significant differences were found in demographic data with P value = 0.245 or complication rates with P value = 0.611 among the groups. At the 2-week follow-up, stone-free rates were 90.2% for Flexible Ureteroscopy which was comparable with mini PCNL and both were significantly higher than ESWL 61.5%.

Conclusions

Mini PCNL and Flexible URS demonstrated comparable stone-free rates for moderate-sized, hard lower pole renal stones, surpassing ESWL. However, Mini PCNL showed longer operative times, increased radiation exposure, and elevated risks of complications and morbidity compared to Flexible URS. Considering these factors, Flexible URS might be recommended in those types of stones.

Trial Registration

Our study has been approved by local ethical committee Kafrelsheikh university (KFSIRB20069) on 30/10/2023 and by clinical trials (NCT06120257) on 15/12/2023.

Introduction

Renal Urolithiasis is a very common disease, management of renal stones involves a spectrum of options, ranging from watchful monitoring to various interventions such as extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), mini-PCNL, flexible ureterorenoscopy (F-URS), laparoscopy, and open surgery [1]. The evolution of endourologic technology has dramatically minimized the necessity for open surgical procedures, now accounting for a mere 1–2% of kidney stone management cases [2].

Addressing lower pole (LP) renal stones poses a special challenge due to the lower pole anatomical variations so the lower pole renal stones have special guidelines in their treatment [3], one of the main predictors of the lower pole renal stones are the characters of the lower calyx as infundibular (IF) length, IF width and infundibulo-pelvic angle [4]. The European Association of Urology (EAU) urolithiasis guideline outlines distinct preferences based on stone size regardless stone composition or density; PCNL is the primary choice for radiopaque renal stones exceeding 2 cm, while ESWL or FURS takes precedence for stones smaller than 1 cm. However, for stones ranging between 1 and 2 cm, the decision among ESWL, FURS, and PCNL depends on multifaceted anatomical and stone factors [5].

The progressive refinement of endourological technology has ushered in a new era of miniaturized instruments, paving the way for minimally invasive techniques like mini and micro PCNL [6]. The latest iterations of FURS and minimally invasive PNL techniques (MIP) have significantly curtailed morbidity, delivering commendable stone-free rates (SFRs). Yet, the inclination towards ESWL persists among several practitioners owing to its perceived minimal invasiveness [7].

This study endeavors to compare the efficacy, success rates, and incidence of complications associated with F-URS, ESWL, and Mini PCNL in managing lower pole renal hard stones measuring less than 2 cm in size. By scrutinizing these minimally invasive approaches, this research aims to offer critical insights into optimizing treatment strategies for this specific cohort of patients.

Patients & methods

Study design and patient selection

This prospective comparative interventional study enrolled 414 adult patients (both sexes, aged over 18 years) diagnosed with a single lower pole renal stone ≤ 2 cm between March 2021 and September 2023 at Kafrelsheikh University’s Urology Department. Ethical approval was obtained from the University Hospitals’ Ethical Committee, and patients provided informed consent aligned with Good Clinical Practice and the Declaration of Helsinki.

Inclusion and exclusion criteria

Inclusion criteria encompassed patients with a single stone measuring 1–2 cm, hard stone (HU values greater than 950) and age over 18 years old. Exclusion criteria involved multiple or very small/large stones, age under 18 years old, BMI > 40 kg/m², bleeding disorders, renal anatomical abnormalities, distal obstruction, or musculoskeletal deformities.

Randomization and groups

Eligible patients meeting inclusion criteria were randomly allocated into three subgroups using a computer-generated random table.

• Group A (FURS): Underwent flexible ureteroscopy with holmium laser lithotripsy.

• Group B (ESWL): Received extracorporeal shock wave lithotripsy.

• Group C (Mini PCNL): Underwent laser lithotripsy via mini percutaneous nephrolithotomy.

Procedures

• Preoperative Evaluation: Comprehensive medical history, physical analysis, urine culture, renal function tests, blood work, and radiological imaging (KUB and NCCT abdomen/pelvis).

• Intervention techniques:

Flexible ureteroscopic laser lithotripsy group

• Preoperative administration of IV antibiotics (third generation cephalosporin); patients positioned under general anesthesia in lithotomy position with C-arm fluoroscopy.

• Guidewire insertion up to the renal pelvis, followed by ureteral dilation using serial Teflon dilators and introduction of a 11–13 Fr ureteral access sheath for flexible ureteroscopy (FURS) (Boston^® scientific (lithovue).

• FURS insertion assisted by fluoroscopy, employing a holmium laser fiber (Lisa^® laser, Sphinx 100, Germany) for stone dusting (long pulse, low energy, high frequency).

• Post-procedure, placement of Double J ureteric stent or ureteric catheter, with catheter removal after 48 h.

Extracorporeal shock wave lithotripsy (ESWL) group

• Outpatient treatment using electromagnetic lithotripsy(STORZ^® MEDICAL Modulith SLX-F2 FD21, Germany) after Pre maneuver administration of IV antibiotics (third generation cephalosporin); patients positioned supine with affected side opposite the lithotripsy machine.

• Topical anesthesia administered, stone localization via fluoroscopy in different planes, followed by shock wave delivery.

• we start with low frequency 1 Hz (60 shoots per minute) then Gradual increase in shock wave intensity to 1.5 Hz (90 shoots per minute). With 3500 shoots per session.

• patients discharged on the same treatment day.

Mini percutaneous nephrolithotomy (Mini-PCNL) group

• Preoperative IV antibiotic administration (third generation cephalosporin); patients placed under general anesthesia and positioned in prone, then guided by C-arm fluoroscopy.

• Guidewire insertion up to the renal pelvis, followed by nephrostomy puncture guided by real-time ultra-fluoroscopy.

• Insertion of Mini-PCNL (Karl Storz^® MIP M 12 Fr nephroscope and a 16 Fr access sheath, Tuttlingen, Germany) with holmium laser for stone dusting using the same laser settings of flexible ureteroscopy (long pulse mode, low energy, high frequency).

• Post-procedure placement of Double J ureteric stent or ureteric catheter, with catheter removal after 48 h.

Intraoperative data collection

Operative times were recorded for FURS (from cystoscopy to stent insertion), ESWL (from shock wave initiation to completion), and Mini-PCNL (from needle puncture to nephrostomy tube insertion).

Result

Out of 454 patients assessed for suitability, only 414 patients enrolled in our study, randomized as 153 patients (37%), 117 patients (28%) and 144 patients (35%) in F-URS, ESWL and Mini PCNL group respectively. as shown in the CONSORT chart. Figure 1.

Fig. 1.

Randomization of eligible cases into three subgroups

Regarding to demographic and stone characteristics among three groups: flexible ureteroscope, ESWL, and Mini PCNL

• Gender Distribution: No significant difference was found in gender distribution among the groups.

• Height, weight and BMI: No significant difference was found in Height, weight and BMI distribution among the groups.

• Age and Hounsfield Units (HU): There were no significant differences in age or HU values among the groups.

• Stone Size: There were no significant differences in stone size among the groups. Table 1.

Table 1.

Comparison of demographic, anthropometric, and stone characteristics among studied groups

	Flexible ureteroscope group N = 153 (%)	ESWL group N = 117 (%)	Mini PCNL group N = 144 (%)	χ2	p
Gender
Female Male	39 (25.5%) 114 (74.5%)	69 (59%) 48 (41%)	39 (27.1%) 105 (72.9%)	2.813	0.245
	Mean ± SD	Mean ± SD	Mean ± SD	F	p
Age (year)	46.75 ± 13.46	43.82 ± 11.67	43.39 ± 10.69	1.619	0.202
Weight (kg)	79.96 ± 8.22	80.66 ± 7.39	78.72 ± 7.18	0.833	0.437
Height (m)	1.75 ± 0.07	1.72 ± 0.07	1.73 ± 0.06	2.239	0.11
BMI(kg/m2)	26.21 ± 2.56	27.36 ± 2.67	26.37 ± 2.56	2.838	0.062
HU	1219.12 ± 324.08	1161.2 ± 256.39	1242.86 ± 308.95	0.994	0.372
Stone size(mm)	13.4 ± 3.7	12.86 ± 3.29	13.48 ± 3.33	1.207	0.133

F One way ANOVA test χ²Chi square test F p1 difference between flexible and ESWL groups p2 difference between ESWL and Mini PCNL groups p3 difference between flexible and mini PCNL groups *p < 0.05 is statistically significant **p ≤ 0.001 is statistically highly significant

The SFR was the primary outcome, defined as the status in which complete disintegration and absence of the stone were diagnosed or the presence of remaining clinically insignificant residual fragments of 4 mm or less after a single session of procedure. The remaining fragments greater than 4 mm in size warranted another session, which was considered an auxiliary treatment [8].

Stone free rate (SFR) after two weeks

• The Flexible Ureteroscope group demonstrated a comparable SFR with Mini PCNL group (90.2%) and (83.3%) respectively. But Higher SFR compared to the ESWL (61.5%) group. The chi-square test indicated a substantial difference (χ2 = 20.095, p < 0.001), and the trend across the groups was notably significant (chi-square for trend p = 0.001), showing a decreasing trend in SFR from Flexible Ureteroscope to ESWL and Mini PCNL Table 2.

Table 2.

Comparison between the studied groups regarding SFR after single procedure and need for auxiliary intervention

	Flexible ureteroscope group N = 153(%)	ESWL group N = 117 (%)	Mini PCNL group N = 144(%)	χ2	p
Two weeks
Free Residual Failed	138 (90.2%) 15 (9.8%) 0 (0%)	72 (61.5%) 27 (23.1%) 18 (15.4%)	120 (83.3%) 24 (16.7%) 0 (0%)	MC	< 0.001**
p (chi square for trend)	P1 < 0.001*	P 2 0.004*	P3 0.315
Need for auxiliary intervention	15 (9.8%)	45 (38.5%)	24 (16.7%)	28.164	< 0.001**

χ²Chi square test MC Monte Carlo test KW Kruskal Wallis test p1 difference between flexible and ESWL groups p2 difference between ESWL and Mini PCNL groups p3 difference between flexible and mini PCNL groups *p < 0.05 is statistically significant **p ≤ 0.001 is statistically highly significant Wx Wilcoxon signed rank test

Need for auxiliary intervention

• The Flexible Ureteroscope group exhibited a lower requirement for auxiliary intervention (9.8%) compared to the ESWL group (38.5%) and notably less than the Mini PCNL group (16.7%). The chi-square test showed a significant difference (χ2 = 28.164, p = 0.001) Table 2.

Complications

• There was no substantial difference in complication rates among the groups (χ2 = 0.985, p = 0.611). Most groups reported a similar absence of complications, with the Flexible Ureteroscope group slightly higher at 82.4%.

Specific complications (UTI, gross hematuria, fever, severe Colic pain, steinstrass)

• No significant variations in these specific complications were observed among the groups Table 3.

Table 3.

Comparison between the studied groups regarding complications

	Flexible ureteroscope group N = 153(%)	ESWL group N = 117 (%)	Mini PCNL group N = 144(%)	χ2	p
Complications				0.985	0.611
Absent	126 (82.4%)	96 (82%)	105 (72.9%)
Present	27 (17.6%)	21 (18%)	39 (27.1%)
UTI Gross Hematuria Fever Sever Colic pain Steinstrass	3 (2%) 6 (4%) 6 (4%) 12 (8%) 0 (0%)	3 (1%) 0 (0%) 0 (0%) 9 (7.6%) 9 (7.6%)	0 (0%) 12 (8%) 12 (8%) 15 (10%) 0 (0%)	MC MC MC 0.844 MC	0.3 > 0.999 0.3 0.656 0.06
Modified clavien
Grade I	21 (77.8%)	12 (57.1%)	27 (69.2%)
Grade II	6 (22.2%)	0 (0%)	12 (30.8%)	MC	0.019*
Grade IIIa	0 (0%)	9 (42,9%)	0 (0%)
	Mean ± SD	Mean ± SD	Mean ± SD
Reduction in HB level	0.22 ± 0.31	-	0.98 ± 0.44	t= -9.89	< 0.001**

Modified Clavien grade for complications

• The Flexible Ureteroscope group displayed notably lower modified Clavien Grade II complications compared to both ESWL and Mini PCNL groups (Monte Carlo test p 0.019).

• Reduction in HB level: Mini PCNL group incurred significantly more reduction in Hemoglobin level post operative compared to The Flexible Ureteroscope group (p < 0.001).

χ²Chi square test MC Monte Carlo test KW Kruskal Wallis test p1 difference between flexible and ESWL groups p2 difference between ESWL and Mini PCNL groups p3 difference between flexible and mini PCNL groups *p < 0.05 is statistically significant **p ≤ 0.001 is statistically highly significant Wx Wilcoxon signed rank test.

Operative data in Table 4

Table 4.

Comparison between the studied groups regarding operative data

	Flexible ureteroscope group N = 153(%)	ESWL group N = 117 (%)	Mini PCNL group N = 144(%)	χ2	p
	Mean ± SD	Mean ± SD	Mean ± SD
Operative time	40.0 ± 6.36	36.05 ± 5.98	50.75 ± 13.37	29.831	< 0.001**
LSD	P1 0.049*	P2 < 0.001**	P3 < 0.001**
	Median(IQR)	Median(IQR)	Median(IQR)	KW	p
Radiation time(min)	3(2.67–3.33)	9.25(6.5–11.18)	4.34(3.25–5)	77.026	< 0.001**
Pairwise	P1 < 0.001**	P2 < 0.001**	P3 < 0.001**
LOS (h)	60(48–72)	2(1–2)	72(48–72)	92.641	< 0.001**
Pairwise	P1 < 0.001**	P2 < 0.001**	P3 0.419
Total cost	16,850(16600 − 16850)	4400(1800–16800)	8250(8000 − 8250)	49.004	< 0.001**
Pairwise	P1 < 0.001**	P2 0.464	P3 < 0.001**

χ²Chi square test MC Monte Carlo test KW Kruskal Wallis test p1 difference between flexible and ESWL groups p2 difference between ESWL and Mini PCNL groups p3 difference between flexible and mini PCNL groups *p < 0.05 is statistically significant **p ≤ 0.001 is statistically highly significant Wx Wilcoxon signed rank test

• Operative Time: Mini PCNL group had significantly longer operative times compared to ESWL and Flexible Ureteroscope groups (p < 0.001).

• Radiation Time: ESWL exhibited notably higher radiation times compared to Flexible Ureteroscope and Mini PCNL groups (p < 0.001). Figure 2.

Fig. 2.

Bar chart showing difference between groups regarding radiation time

• Length of Stay (LOS): Both the Flexible Ureteroscope and Mini PCNL groups had significantly longer LOS compared to the ESWL group (p < 0.001).

• Total Cost: The Flexible Ureteroscope group incurred significantly higher costs compared to both ESWL and Mini PCNL groups (p < 0.001).

In summary, the Flexible Ureteroscope group demonstrated superior SFR, lower need for auxiliary intervention, and fewer Clavien Grade II complications despite longer operative times, increased LOS, and higher costs compared to ESWL and Mini PCNL groups. ESWL had shorter operative times but higher radiation exposure, lower SFR, and increased need for auxiliary intervention. Mini PCNL presented intermediate results between the two other methods.

Discussion

This study focuses on comparing three distinct treatments for lower pole renal stones: Flexible Ureteroscopy (F-URS), Extracorporeal Shock Wave Lithotripsy (ESWL), and Mini Percutaneous Nephrolithotomy (Mini-PCNL). These techniques vary in invasiveness, with newer approaches like F-URS and Mini-PCNL aiming for decreased morbidity while ESWL remains less invasive but potentially less effective [9, 10]. The research aligns with established guidelines and concentrates on the complexities posed by hard stones and anatomical variations in the lower pole, seeking to address treatment challenges within this specific context.

One striking observation was the differing SFR among the modalities, with newer methods like F-URS and Mini-PCNL showing promise in reducing morbidity and enhancing stone clearance, while ESWL, though less invasive, also demonstrates certain advantages [11]. This study provides a comprehensive assessment tailored to guidelines treatment strategies, considering the intricate interplay of anatomical variations and stone characteristics in managing lower pole renal stones.

The Stone Free Rate (SFR) was notably different among the treatment modalities in this study Flexible Ureteroscopic Lithotripsy (FURS) exhibited the highest SFR at 90.2%, significantly surpassing both Extracorporeal Shock Wave Lithotripsy (ESWL) at 61.5% and Mini Percutaneous Nephrolithotomy (Mini PCNL) at 83.3% (P-value < 0.001). These findings corroborate with previous studies, like Kruck et al. [7] found relatively higher SFRs for FURS and Mini PCNL compared to ESWL. However, studies by Kumar et al., Aboutaleb et al., and Resorlu et al. demonstarte higher SFRs for Mini PCNL over ESWL and FURS, diverging from the predominant observations [5, 12, 13].

Sedation is important to optimize the patients tolerance during the procedures which will improve the stone free rate and procedure outcome. Shock wave lithotripsy (SWL) can be effectively performed using either oral analgesia or general anesthesia. Although general anesthesia can enhance stone targeting, oral analgesia offers the benefit of a minimally invasive and outpatient approach to stone management. Various studies have shown that oral opioids and NSAIDs are effective in alleviating pain during ESWL [14]. Despite in our study, we used Topical anesthesia not sedation.

The requirement for auxiliary procedures varied significantly among the treatment groups in this study. In the Mini PCNL group, 15.7% required additional procedures, including ESWL sessions, FURS, or Mini Percutaneous Nephrolithotomy (Mini PCNL). In the ESWL group, 38.5% needed further interventions, primarily subsequent ESWL sessions, FURS, or Mini PCNL. Conversely, In the Flexible Ureteroscopic Lithotripsy (FURS) group, only 9.8% underwent additional procedures, all involving ESWL. (P-value < 0.001).

This contrast with Dhayal’s study, where Mini PCNL had the lowest need for additional procedures at 1.7%, compared to FURS at 10% and ESWL at 18.33% (P = 0.031) [15]. Resorlu et al. similarly reported a higher incidence of auxiliary procedures after ESWL (21.9%) compared to PCNL (5.7%) and FURS (8.7%) (p < 0.001) [13].

The choice of auxiliary procedure depends on several factors, including stone composition, residual stone size and location, patient BMI, renal anatomy, and preferences of both the patient and urologist. These factors collectively influence the decision-making process regarding the type of additional intervention required to manage residual stones effectively.

The study compared operative times among different techniques, revealing varying durations. Mini Percutaneous Nephrolithotomy (Mini PCNL) was an average of 50.75 ± 13.37 min, while Extracorporeal Shock Wave Lithotripsy (ESWL) and Flexible Ureteroscopic Lithotripsy (FURS) showed shorter durations of 36.05 ± 5.98 min and 40.0 ± 6.36 min respectively (P = 0.001). Other studies echoed these differences, demonstrating shorter times for ESWL, longer durations for FURS, and Mini PCNL, highlighting the variations influenced by surgeon expertise, calculation methods, and managing diverse kidney stone locations. In our study, the fluoroscopy durations for ESWL, FURS, and Mini PCNL revealed marked differences in imaging times. ESWL exhibited a notably longer median duration of 9.15 min (6.5–11.18 min), significantly exceeding Mini PCNL(4.34 min, 3.25–5 min) and FURS (3 min, 2.67–3.33 min) with a substantial P-value of < 0.001. Also, Resorlu et al. found PNL to have a longer duration (57.5 ± 22.1 s) than FURS (43.1 ± 17) with a significant difference (p < 0.001) [13]. Moreover, another study highlighted the extensive fluoroscopy time in Mini PCNL (170.8 ± 1.5 s) compared to FURS (31.5 ± 1.7 s) (p < 0.01) [5]. These diverse results underscore considerable variations in imaging durations across these stone management procedures, emphasizing substantial differences in fluoroscopy times between ESWL, FURS, and Mini PCNL techniques in different research investigations.

The study demonstrate time to radiation exposure during stone management with three modalities The duration of radiation exposure was notably longer for ESWL compared to both flexible ureteroscopy (URS) and Mini PCNL (percutaneous nephrolithotomy). To overcome this problem, Chang et al. developed a real-time tracking ultrasound-based system for renal stones achieving real time tracking of the stone without excessive radiation exposure to the patient [16]. In our study, we use fluoroscopy for stone localization as ultrasound localization for renal stone not available in our institute.

This study assessed post-operative complications using the Clavien-Dindo Classification for three procedures: FURS, ESWL, and Mini PCNL. Although the complication rates varied—17.6% for FURS, 18% for ESWL, and 27.1% for Mini PCNL—there was no significant difference in the overall incidence of postoperative complications among these groups. These findings were consistent with Kumar’s study, which noted a higher but non-significant incidence of complications in Mini PCNL compared to ESWL and FURS [5].

Contrasting outcomes were found in Dhayal IR et al.‘s research, highlighting significant differences in complication rates between the groups [15]. Similar studies by Kruck et al. and Resorlu et al. [7, 13] echoed higher complication rates associated with PCNL compared to ESWL and FURS. The occurrences of fever, UTI, and steinstrasse-related severe renal colic demonstrated variances across these procedures in different studies, showcasing discrepancies in complication profiles among them. These diverse findings emphasize the necessity of understanding complications linked to different stone treatment methods based on individual patient characteristics.

Hospital stays varied significantly across renal stone treatments: FURS showed a median of 60 h, ESWL at 2 h, and Mini PCNL the longest at 72 h. Previous studies echoed these differences: Aboutaleb’s 2012 research outlined shorter ESWL stays (average of 0.73 days) compared to PCNL and FURS, emphasizing diverse durations. Kruck et al.‘s findings emphasized extended stays for FURS and Miniperc, averaging 2.2 h, 4.5 days, and 2.3 days, respectively (p < 0.001) [7].

This research delved into the economic aspects of stone treatments, dissecting expenses per patient involving procedure charges, in-patient care, and management of associated complications. Findings pinpointed ESWL as a cost-efficient method with fewer complications. Conversely, FURS demonstrated higher expenses compared to other modalities, while Mini-PCNL emerged as the most cost-effective approach for 1–2 cm renal stones treated in a single session. Despite its lower cost, shock wave lithotripsy was found to be less effective. However, another perspective from Wymer et al. favored FURS as the most cost-effective surgical intervention for 1–2 cm renal stones, regardless of their location within the kidney [17].

Limitation of study

We used dusting mode with mini PCNL of the same laser settings of flexible URS which may take longer operative time than traditional fragmentation.

The study needs to include more variety of stone compositions to standardize the most suitable approach.

ESWL may require a longer follow up for stone free than other interventions, such as URS or PCNL to achieve complete stone clearance. So, the two weeks follow up may have underestimated the true stone free rate for ESWL group as some patients may have require a longer duration of follow up to fully clear stone fragments.

Variables such as infundibulo-pelvic angle, calyceal length, skin-to-stone distance, infundibulum neck width, and stone composition are known to influence ESWL outcomes. These factors warrant consideration in future studies to optimize patient selection and improve treatment efficacy.

Conclusions

In addressing lower pole moderate-sized hard renal stones, both FURS and mini PCNL demonstrate significant superior success rates and reduced need for retreatment when compared to ESWL. However, the invasiveness and potential for minor blood loss pose limitations to Mini PCNL. FURS offers potential advantages in terms of decreased morbidity, radiation exposure, and hospitalization duration, maintaining comparable success rates to mini PCNL. This study paves the way for FURS to be standard for lower pole hard renal stones.Yet, larger prospective randomized trials are imperative to validate and substantiate these observations.

Abbreviations

NCCT

Non contrast Computed tomography

KUB

Kidney, ureter, and bladder radiograph

PCNL

Percutaneous nephrolithotomy

FURS

Flexible Ureteroscopy

ESWL

Extracorporeal Shock Wave Lithotripsy

SFR

Stone Free Rate

Author contributions

Khaled Magdy Zeinelabden: Analysis and interpretation of data. Elsayed Abdelhalim Elsayed: Acquisition of data. Mohamed Galal: Drafting of the manuscript and statistical analysis. Tarek Abdelbaky: Critical revision. Hossam Nabeeh: revision of manuscript. All authors read and approved the final version of the manuscript.

Funding

there is no financial support or sponsorship.

Data availability

The data is contained within the manuscript, any missing details will be available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was approved by the scientific research ethics committee of Kafrelsheikh university (KFSIRB200-69). All patients provided written informed consent prior to surgery.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.