Abstract
Background
Urinary stones are a common disease in urology, and stones in ureteral strictures can easily lead to obstruction and subsequent infection. If the upper ureteral impacted stones with infection are not treated promptly, further renal impairment and urinary sepsis can occur. Mini-percutaneous nephrolithotomy (PCNL) and flexible ureteroscopic lithotripsy (fURSL) are common methods for the treatment of upper ureteral impacted stones with infection, but their superiority remains debated. To this end, we designed this study to compare the effects of mini-PCNL versus fURSL in patients with upper ureteral impacted stones with infection.
Methods
The data of 182 patients with upper ureteral impacted stones and infection admitted to The First Affiliated Hospital of Chengdu Medical College from January 2021 to December 2024 were retrospectively collected. The patients were divided into an antegrade group (n=88) and a retrograde group (n=94) according to the method they received. The antegrade group was treated with minimally invasive PCNL, and the retrograde group was treated with fURSL. The main outcome measure included inflammatory markers [white blood cell count (WBC), C-reactive protein, interleukin 6, and procalcitonin], and renal function (serum creatinine and urea nitrogen). The other indicators included surgery-related outcomes (operation time and stone-free status) and postoperative complications.
Results
Compared with the retrograde group, the one-time stone clearance rate in the antegrade group was significantly higher (96.59% vs. 86.17%; P=0.03). Compared with that in the retrograde group, the operation time in the antegrade group was significantly longer (62.73±4.82 vs. 51.84±5.02 min; P<0.001). There were no statistically significant differences in leukocyte, C-reactive protein, or interleukin 6 levels between the two groups before treatment (P>0.05). Compared to the retrograde group 3 days after surgery, the antegrade group had a significantly higher WBC [(10.92±2.88 vs. 8.92±2.62)×109/L; P<0.001], C-reactive protein (12.94±4.72 vs. 10.82±4.82 mg/L; P=0.003), and interleukin 6 level (18.74±9.82 vs. 15.81±9.27 ng/L; P=0.04). There was no statistically significant difference in postoperative complications between the two groups (P>0.05).
Conclusions
PCNL can improve stone clearance rate, but the operation time is long and relatively invasive.
Keywords: Percutaneous nephrolithotomy (PCNL), flexible ureteroscopy, proximal ureteral stone, infection
Highlight box.
Key findings
• Percutaneous nephrolithotomy can improve the stone clearance rate, but the operation time is long and relatively invasive.
What is known and what is new?
• Minimally invasive percutaneous nephrolithotomy and flexible ureteroscopic lithotripsy are common methods for the treatment of upper ureteral impacted stones with infection.
• Compared with flexible ureteroscopic lithotripsy, percutaneous nephrolithotomy can improve the stone clearance rate.
What is the implication, and what should change now?
• Percutaneous nephrolithotomy is more effective in improving the stone clearance rate in the treatment of upper ureteral impacted stones with infection. For patients with good health conditions, percutaneous nephrolithotomy should be the first choice in the management of upper ureteral impacted stones with infection.
Introduction
Ureteral stones are more common in men than in women, and are more common in people aged 40 to 60 years. There are three physiological strictures in the ureter, which are located at the transition between the renal pelvis and the ureter, the transiliac blood vessels of the ureter, and the internal segment of ureteral bladder wall (1,2). Surgery is an important treatment for patients with impacted stones in the upper ureters. Impacted ureteral stones can be treated with percutaneous nephrolithotomy (PCNL), which has a high rate of stone clearance, but the requirements for the establishment of a stone removal channel are high in terms of the patient’s constitution and position; moreover, this procedure is prone to intraoperative bleeding and puncture injury to the adjacent organs (3,4). Flexible ureteroscopic lithotripsy (fURSL) is also a minimally invasive procedure that is easier to perform and does not require puncture and dilation (5). While both procedures are equally recommended as proximal ureteral treatments (6), there is still controversy regarding which type of surgery is superior. This study aimed to compare the effects of minimally invasive (mini-) PCNL with those of fURSL in patients with proximal ureteral impacted stones with infection. We present this article in accordance with the STROBE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-277/rc).
Methods
General information
A total of 182 patients with upper ureteral impacted stones with infection admitted to The First Affiliated Hospital of Chengdu Medical College from January 2021 to December 2024 were retrospectively enrolled and divided into an antegrade group (n=88) and a retrograde group (n=94) according to the method they received. The inclusion criteria were as follows: (I) upper ureteral impacted stones (radiographically confirmed ureteral stones located above the L4 vertebra), stones remaining at the same site for >8 weeks; (II) a stone diameter of 1–2 cm; (III) age 18–65 years; (IV) unilateral ureteral stones; and (V) failure of extracorporeal shock wave lithotripsy; (VI) all patients had received a nephrostomy tube. Meanwhile, the exclusion criteria were as follows: (I) urinary system malformations; (II) history of urological surgery; (III) diseases of the hematopoietic system; (IV) malignant tumors; (V) immune system disorders; and (VI) previous liver, kidney, heart, or cerebropulmonary dysfunction. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of The First Affiliated Hospital of Chengdu Medical College (No. c202401248). The requirement for individual consent was waived due to the retrospective nature of the analysis.
Treatment
All patients received antibiotic treatment during the perioperative period, and the selection of antibiotic drugs was based on bacterial culture results. (I) The antegrade group underwent treatment with PCNL. After general anesthesia, a catheter (5 Fr) was placed into the ureter on the affected side in conventional lithotomy position, and normal saline was injected to induce the formation of artificial hydronephrosis. The patient was shifted to the prone position for renal pelvis puncture, a needle was inserted between the 11th and 12th ribs, and the puncture was completed in the subscapular angle and posterior axillary line area. After the dilation (up to 18 Fr), a percutaneous tract (18 Fr; Karl Storz, Tuttlingen, Germany) was placed. Then, laser lithotripsy was performed with an 8/9.8 Fr ureteroscope. And finally, a double-J tube and a catheter were placed. The surgery was performed under the guidance of fluoroscopy. (II) The retrograde group was treated with fURSL. After general anesthesia, a guidewire was placed conventionally in the lithotomy position. The ureteral opening reached the calculus impacted position, and the ureteroscope was placed in retrograde fashion under the guidance of the guidewire for holmium laser lithotripsy. The residual stone fragments were removed by a basket wire, followed by a double-J ureteral stent placement. There were no clinical studies during the research period, so the choice of surgical approach for patients was mainly based on the doctor’s preference. After admission, antibiotic treatment was given, and the type of antibiotic depended on the bacterial culture results. Antibiotics were used until the bacterial culture turned negative.
Data collection
(I) The main outcome measures included: inflammatory markers before and 3 days after surgery [white blood cell count (WBC), C-reactive protein, interleukin 6, and procalcitonin], and renal function before and 3 days after surgery (serum creatinine and urea nitrogen). (II) surgery-related indicators, including operation time, one-time stone clearance rate, intraoperative complications (intraoperative bleeding, ureteral perforation, hypotension, tachycardia) and postoperative complications (renal colic, ureteral perforation, urosepsis, fever, acute kidney injury). (III) Post-operational hospital days and antibiotics use time; (IV) General information included the patient’s age, gender, body mass index, stone location, stone size, and number of stones on admission.
Definition
Stone-free status was defined as no residual stones larger than 2 mm on abdominal computed tomography (CT) examination 7 days after surgery (7). Infection was defined as the presence of urinary tract irritation symptoms such as frequent urination, urgency, and pain, with a bacterial count in urine culture was ≥105 CFU/mL. Intraoperative bleeding was defined as blood loss ≥800 mL.
Statistical analysis
SPSS 26.0 (IBM Corp., Armonk, NY, USA) was used to complete the data analysis of this study, with P<0.05 indicating a statistically significant difference. All the continuous data were normally distributed and are expressed as the mean ± standard deviation; the independent samples t-test was used to analyze the differences between groups. Count data are expressed as numbers and percentages, and the chi-squared test was used to analyze the differences between groups.
Results
Patient inclusion
During the study period, 201 patients met the inclusion criteria, of whom 19 also met the exclusion criteria, and 182 patients were ultimately included in this study. Of these, 88 patients underwent mini-PCNL and 94 patients underwent fURSL. The flowchart of patient inclusion is provided in Figure 1.
Figure 1.
Flowchart of patient inclusion.
Comparison of the primary clinical characteristics of the two groups of patients on admission
There were no statistically significant differences in age, gender, body mass index, stone location, stone size, and number of stones between the two groups (P>0.05) (Table 1).
Table 1. Comparison of the primary clinical features of the two groups at the time of admission.
| Variable | Antegrade group (n=88) | Retrograde group (n=94) | t/χ2 value | P value |
|---|---|---|---|---|
| Age (years) | 40.92±5.12 | 41.34±5.88 | 0.512 | 0.61 |
| Gender | 0.367 | 0.54 | ||
| Male | 62 (70.45) | 70 (74.47) | ||
| Female | 26 (29.55) | 24 (25.53) | ||
| Body mass index (kg/m2) | 23.81±2.81 | 24.03±2.73 | 0.536 | 0.59 |
| Stone site | 0.107 | 0.74 | ||
| Right | 48 (54.55) | 49 (52.13) | ||
| Left | 40 (45.45) | 45 (47.87) | ||
| Stone size (cm) | 1.53±0.28 | 1.54±0.30 | 0.232 | 0.82 |
| Number of stones | 2.08±0.73 | 2.12±0.78 | 0.357 | 0.72 |
Data are presented as mean ± standard deviation or n (%).
Comparison of surgery-related indices between the two groups
Compared with that in the retrograde group, the operation time in the antegrade group was significantly longer (62.73±4.82 vs. 51.84±5.02 min; P<0.001) while the one-time stone clearance rate was significantly higher (96.59% vs. 86.17%; P=0.03) (Table 2).
Table 2. Comparison of surgery-related indices between the two groups.
| Variable | Antegrade group (n=88) | Retrograde group (n=94) | t/χ2 value | P value |
|---|---|---|---|---|
| Operative time (min) | 62.73±4.82 | 51.84±5.02 | 14.909 | <0.001 |
| One-time stone clearance rate | 85 (96.59) | 81 (86.17) | 4.924 | 0.03 |
| Intraoperative bleeding | 1 (1.14) | 1 (1.06) | 0.442 | 0.51 |
| Ureteral perforation | 0 (0.00) | 0 (0.00) | – | – |
| Hypotension | 5 (5.68) | 7 (7.45) | 0.033 | 0.86 |
| Tachycardia | 6 (6.82) | 5 (5.32) | 0.012 | 0.91 |
Data are presented as mean ± standard deviation or n (%).
Comparison of inflammatory markers and renal function between the two groups before and after treatment
There were no statistically significant differences in leukocyte, C-reactive protein, or interleukin 6 levels between the two groups before treatment (P>0.05). Compared with the flexible ureteroscopy at 3 days after surgery, the antegrade group had a significantly higher WBC [(10.92±2.88 vs. 8.92±2.62)×109/L, P<0.001], C-reactive protein (12.94±4.72 vs. 10.82±4.82 mg/L; P=0.003), and interleukin 6 (18.74±9.82 vs. 15.81±9.27 ng/L; P=0.04). There was no statistically significant difference in procalcitonin, creatinine, or urea nitrogen levels between the two groups before and after treatment (P>0.05) (Table 3).
Table 3. Comparison of inflammatory markers and renal function between the two groups before and after treatment.
| Variable | Antegrade group (n=88) | Retrograde group (n=94) | t value | P value |
|---|---|---|---|---|
| White blood cell count (109/L) | ||||
| Before treatment | 14.83±2.91 | 14.92±3.02 | 0.204 | 0.84 |
| 3 d postoperatively | 10.92±2.88 | 8.92±2.62 | 4.905 | <0.001 |
| C-reactive protein (mg/L) | ||||
| Before treatment | 23.92±5.82 | 24.64±6.03 | 0.819 | 0.41 |
| 3 d postoperatively | 12.94±4.72 | 10.82±4.82 | 2.995 | 0.003 |
| Interleukin 6 (ng/L) | ||||
| Before treatment | 39.74±12.84 | 41.82±13.92 | 1.046 | 0.30 |
| 3 d postoperatively | 18.74±9.82 | 15.81±9.27 | 2.071 | 0.04 |
| Procalcitonin (ng/mL) | ||||
| Before treatment | 1.72±0.52 | 1.80±0.56 | 0.997 | 0.32 |
| 3 d postoperatively | 0.44±0.21 | 0.40±0.19 | 1.349 | 0.18 |
| Blood creatinine (μmol/L) | ||||
| Before treatment | 135.39±32.81 | 131.82±38.74 | 0.669 | 0.51 |
| 3 d postoperatively | 87.89±20.94 | 85.82±18.27 | 0.172 | 0.48 |
| Urea nitrogen (mmol/L) | ||||
| Before treatment | 11.72±2.81 | 11.90±2.92 | 0.423 | 0.67 |
| 3 d postoperatively | 8.71±1.91 | 8.92±1.98 | 0.727 | 0.47 |
Data are presented as mean ± standard deviation. d, days.
Comparison of postoperative complications between the two groups
There was no significant difference between the two groups in terms of postoperative complications, such as renal colic, ureteral perforation, and urosepsis (P>0.05) (Table 4).
Table 4. Comparison of postoperative complications between the two groups.
| Variable | Antegrade group (n=88) | Retrograde group (n=94) | t/χ2 value | P value |
|---|---|---|---|---|
| Renal colic | 5 (5.68) | 3 (3.19) | 0.209 | 0.65 |
| Ureteral perforation | 1 (1.14) | 1 (1.06) | 0.442 | 0.51 |
| Urosepsis | 1 (1.14) | 1 (1.06) | 0.442 | 0.51 |
| Acute kidney injury | 3 (3.41) | 2 (2.13) | 0.006 | 0.94 |
| Fever (38 ℃ or more) | 24 (27.27) | 21 (22.34) | 0.594 | 0.44 |
| Antibiotics use (d) | 5.83±1.73 | 6.02±1.80 | 0.969 | 0.33 |
| Post-operational hospital time (d) | 10.74±2.12 | 10.56±2.34 | 0.726 | 0.47 |
Data are presented as n (%) or mean ± standard deviation. d, days.
Discussion
Impacted ureteral stones are often associated with infection and often require surgical intervention (8-10). Mini-PCNL and fURSL are common surgical methods for patients with impacted stones in the upper ureteral segment with infection. These procedures can effectively reduce surgical trauma, accelerate postoperative recovery. and reduce surgery-related complications compared with traditional laparoscopic surgery or laparotomy (11). However, it remains unclear which of PCNL or fURSL should be preferred. In this study, the effects of mini-PCNL and fURSL on patients with proximal ureteral impacted stones with infection were analyzed, and the results showed that PCNL had a higher one-time stone-free rate. However, the PCNL was also associated with a longer operative time and high levels of postoperative inflammation. Although the differences in operative time and inflammation were statistically significant, all clinical values were within safety limits. Therefore, we believe that PCNL was better in the management of impacted ureteral stones.
PCNL was introduced in the 1970s as a minimally invasive surgical approach for the treatment of kidney stones. Since its inception, PCNL has undergone multiple improvements in technology and equipment. In order to reduce complications such as bleeding and extravasation in PCNL, Jackman et al. introduced mini-PCNL in 1997 to reduce the complications, using a ureteroscope sheath with an inner diameter of 11 Fr and an outer diameter of 13 Fr to establish a channel (12). Compared with standard PCNL, the mini-PCNL had a shorter hospital stay, less hemoglobin drop, less blood transfusion, fewer complications, and a longer operational time (13). PCNL or mini-PCNL can effectively avoid the reflux of lithotripsy to the renal pelvis and can reduce the damage of ureteral mucosa caused by ureteral angulation and twisting during the operation. Additionally, the operating space of the nephroscope in the renal pelvis and kidney is relatively large, the surgical field is clear, and thus the stone can be more accurately and easily located (14,15). PCNL or mini-PCNL has been reported to achieve 99% upper ureteral stone clearance in the first treatment. However, it has the shortcomings of large surgical trauma and slow postoperative recovery, and some patients may develop iatrogenic visceral injury and even septic shock (16,17).
Since its inception, fURSL has been favored by an increasing number of urologists (6,18). Compared with nephroscopy, it is less invasive and allows patients to arise from bed early after surgery. In our study, it was also shown that the fURSL requires less operative time and causes less trauma. In recent years, the use of stone removal nets has reduced the risk of stone drift and residual stones (19). Moving the stone mesh forward in ureteroscopy can block the stone movement path and further prevent stones with a diameter of <1.5 mm from accidentally entering the renal pelvis (20). The fURSL provides faster recovery after surgery and is easy to perform, less time-consuming, and less costly. However, because the proximal ureteral stone is located at the junction of the renal pelvis and the ureter and because the upper part of the stone is relatively dilated due to water accumulation, the upward stone tripsy of retrograde ureteroscopy is more likely to lead to the reflux of lithotripsy into the renal pelvis and the failure of surgery. Moreover, there are certain difficulties in the treatment of stones in the renal pelvis, such as the narrowing and distortion of the ureter below the stone. In these cases, the ureteroscope is unable to reach the stone site smoothly, which can lead to the failure of lithotripsy (21,22). In Wang et al.’s study (23), they examined 58 patients with upper ureteral stones, including 29 patients in the antegrade group and 29 patients in the retrograde group. They found that the stone clearance rate of PCNL was slightly higher than that of fURSL, but there was a greater decrease in hemoglobin and significantly longer hospital stay in the PCNL group, which is consistent with our study. Our study also showed that the PCNL could improve stone clearance rate when compared with fURSL.
Limitations
As we employed a retrospective study design, further prospective, multicenter clinical studies are needed. In addition, the present study was a single-center clinical trial, and the geographical limitations of the clinical sample may affect the external applicability of the results.
Conclusions
Mini-PCNL can improve the stone clearance rate, but it is relatively invasive and requires a longer operation time.
Supplementary
The article’s supplementary files as
Acknowledgments
None.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of The First Affiliated Hospital of Chengdu Medical College (No. c202401248). The requirement for individual consent was waived due to the retrospective nature of the analysis.
Footnotes
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-277/rc
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-277/coif). The authors have no conflicts of interest to declare.
Data Sharing Statement
Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-277/dss
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