Comparison of the Efficacy of Different Surgical Approaches for Complicated Impacted Proximal Ureteral Calculi Based on a New Scoring Standard: A Matched-Pair Analysis

Abstract

Objective:

To compare the clinical efficacy of ureteroscopic lithotripsy (URSL) and percutaneous nephrolithotomy (PCNL) in the treatment of complicated impacted proximal ureteral calculi using a new scoring standard.

Methods:

The data of 45 patients with complicated impacted proximal ureteral calculi (score ≥3 points) who underwent URSL were collected in this retrospective study between January 2015 and April 2021. The definition and scoring standards for preoperative high-risk factors associated with stones included whether the diameter of the stone was >2 cm, stone density was >1000 HU, there was a history of lithotripsy, the degree of hydronephrosis was greater than moderate, and there was an infection. Scores for stones were then assigned (yes = 1, no = 0), and the complicated stone case was defined as a total stone score ≥3 points. During the same period, PCNL was used in 171 patients with complicated impacted proximal ureteral calculi. Forty-five patients were selected as the control group and matched at a 1:1 ratio to index URSL cases regarding age, sex, and body mass index. Perioperative data were compared between the two groups.

Results:

All 90 operations were completed effectively. Compared to the URSL group, the surgical duration of the PCNL group was significantly shorter (53.69 ± 25.07 vs 73.46 ± 27.12 minutes, p < 0.05), stone-free rate (SFR) was significantly higher (93.3% vs 68.9%, p < 0.05), and total treatment cost was lower (US $1678.61 ± 714.86 vs US $3901.45 ± 1069.46, p < 0.05). Conversely, the URSL group had a shorter hospital stay (3.68 ± 2.70 vs 6.39 ± 3.34 days, p < 0.05). There was a significant difference in complication rate between the two groups regarding Clavien grade I, II, or III complications (20.0% in URSL group vs 8.9% in PCNL group, p = 0.037).

Conclusion:

PCNL had a better SFR and higher surgical efficacy, whereas URSL had a shorter perioperative period, but a lower initial SFR. PCNL is often more advantageous for complicated impacted proximal ureteral calculi.

Introduction

Urolithiasis is a common medical condition. Its incidence by the age of 70 years is 11% to 13% in men and 5.6% to 7.0% in women.¹ Ureteral calculus can adversely affect kidney function and cause life-threatening sepsis.^2,3 According to the latest urologic guidelines, extracorporeal shockwave lithotripsy (SWL), ureteroscopic lithotripsy (URSL), and percutaneous nephrolithotomy (PCNL) are the most used treatment methods for proximal ureter stones, but their associated stone-free rates (SFR) and complication rates differ.⁴

Scoring systems such as the Guy's Stone and the Stone size, Tract length, Obstruction, calices N. Essence scores have been introduced to evaluate the surgical efficacy of different kidney stone cases.⁵ Various surgical methods have been used for the treatment of proximal ureteral calculi. Wu et al conducted a meta-analysis and found that URSL should be regarded as the standard treatment for large proximal ureteral calculi.⁶ A retrospective analysis conducted by Bozkurt et al found that PCNL is a safer and more effective treatment for impacted proximal ureteral calculi.⁷ Li et al revealed that the treatment options for impacted proximal ureteral calculi depend on the location of the stone relative to the superior boundary of the fourth lumbar vertebra.⁸ However, thus far, no scoring systems have been developed to guide the treatment of upper ureteral calculi.

Therefore, we aimed to compare the clinical efficacy of URSL and PCNL in the treatment of complicated impacted proximal ureteral calculi by a new scoring standard. In addition, after analyzing the existing data, high-risk factors associated with the characteristics of stones were preoperatively assigned scores, and a better surgical plan for the complicated impacted upper ureteral stones can be decided based on the scores.

Methods

Clinical materials

We retrospectively studied a total of 412 patients with impacted proximal ureteral calculi eligible for treatment between January 2015 and April 2021. The proximal ureteral calculi were defined as located between the ureteropelvic junction and the iliac vessels.⁹ The inclusion criteria for impacted calculi are as follows: the stone has been retained in the ureter for at least 4 weeks; previously failed SWL; hydronephrosis in the ipsilateral renal pelvic collecting system is over 1 cm; and ureteral stricture or polyp formation near the stone. Patients who met any two of these criteria were diagnosed with impacted proximal ureteral calculi.

Exclusion criteria included the following: patients requiring treatment for kidney stones or bilateral ureteral stones at the same time; patients with a solitary kidney and other renal abnormalities; and patients who were lost to follow-up during the study period. Authors had no access to information that could identify individual participants during or after data collection.

The definition and scoring standards for preoperative high-risk factors associated with stones were selected based on findings from existing literature. These high-risk factors included whether the diameter of the stone was >2 cm,¹⁰ stone density was >1000 HU,¹¹ there was a history of lithotripsy,¹² the degree of hydronephrosis was greater than moderate,¹³ and there was infection.¹⁴ Scores for high-risk factors associated with stones were then assigned (yes = 1, no = 0). A complicated stone case was defined as a total stone score ≥3.

All patients underwent preoperative CT examination of the urinary system; Patients' demographic data, such as age, sex, body mass index (BMI), and history of kidney operation was recorded. Preoperative laboratory tests included urinalysis, urine culture, blood count, coagulation function, and creatinine levels. Prophylactic antibiotics were preoperatively administered in all patients, and those with positive urine cultures were treated with sensitive antibiotics to control infection. Due to the study's retrospective nature, the need for informed consent was waived; in addition, the study design was approved by the ShengJing hospital Ethics Review Board, and all methods were performed following the relevant guidelines and regulations.

Forty-five patients in the URSL group were identified as complicated impacted proximal calculi (total stone score ≥3). The matching of the 45 patients from among those 171 PCNL patients was done by propensity score method. During the same period, PCNL was performed in 171 patients with complicated impacted proximal calculi. From this cohort, we selected 45 patients to serve as the control group. The 45 patients were matched at a 1:1 ratio to index URSL cases concerning age, sex, and BMI. When more than one possible match was available, controls were labeled with a random number generator within Excel (Microsoft Corp, Redmond, WA) and PCNL data corresponding to the highest random numbers assigned were selected as controls.

Both procedures were the standard of care at the time and whether patients would receive PCNL or URSL depended on the preference of the surgeon and the availability of the equipment at the operation time. Operative data such as SFR, complication rate, cost, need for auxiliary treatment, and postoperative hospital stay were evaluated.

Surgical technique

Ureteroscopic lithotripsy

For the semirigid URSL procedure, patients were placed in the lithotomy position under epidural or general anesthesia. An 8/9.8F semirigid ureteroscope was advanced into the ureter via a safety guidewire. After the location of the stone was determined, it was directly managed by using a pneumoballistic or holmium laser.

For the flexible URSL, after effectively anesthetizing the patients, a holmium laser (1.0 J 20 HZ, 20 W) fiber was placed via a flexible ureteroscope for stone fragmentation. Stone removal baskets were used routinely in URSL surgery to improve stone removal efficiency. The ureteral access sheath (UAS) (13F) was routinely used in flexible URSL to avoid high irrigation pressure and facilitate the passage of stone fragments. A 6F Double-J tube was routinely placed after the operation.

Percutaneous nephrolithotomy

Patients were placed in the lithotomy position, and artificial hydronephrosis was induced after epidural or general anesthesia. After inserting the ureteral catheter, patients were turned to the prone position, and the target renal calix was punctured under ultrasound guidance. A fascial dilator was used to continuously expand to the desired working tract. After advancing the nephroscope (24F) via the guidewire and determining the location of the stone, ultrasonic and pneumatic lithotripsy was used to break the stone and remove the stone fragments. A 6F Double-J tube was routinely placed, and a nephrostomy tube was placed at end of the operation.

All patients who met the inclusion criteria were followed-up within 3 months after the operation to evaluate clinical efficacy. The degree of hydronephrosis was determined by measuring the anterior and posterior diameter of the hydronephrosis on CT. Hydronephrosis less than 2 cm was considered moderate. The surgical duration was defined as the time from placing the patients in the lithotomy position in the URSL group or placing the patients in the prone position in the PCNL group to the end of anesthesia. The SFR was defined as no postoperative residual stones on the urinary CT scan. Complications were analyzed using a modified Clavien classification; infectious complications were defined as postoperative systemic inflammatory response syndrome symptoms and bleeding complications were defined as postoperative blood transfusion and renal artery embolization. All patients underwent CT examination at 1 month postoperative to determine whether there were residual stones, ureteral stenosis, or hydronephrosis.

Statistical analysis

Data were analyzed by SPSS (version 22; IBM Corporation, Armonk, NY). Continuous variables were compared with Student's t and Mann–Whitney U tests. Proportions of categorical variables were analyzed using the chi-squared or Fisher's exact test. A p-value <0.05 was accepted as statistically significant. All reported p values were two-sided.

Results

All operations were completed effectively and at one time, and there was no conversion to open surgery and secondary surgery. There was no significant difference regarding age, sex, BMI, creatinine level, and clinical features of the stones between the URSL and PCNL groups (p > 0.05) (Table 1).

Table 1.

Demographic Characteristics Data of Patients According to Patients' Group

Parameter	URSL group, N = 45	PCNL group, N = 45	t/χ² value	p
Age	54.40 ± 11.17	52.82 ± 12.58	0.890	0.116
Sex (male/female)	26/19	23/22	2.345	0.126
BMI	23.89 ± 3.62	23.67 ± 3.53	0.410	0.782
Creatinine	80.76 ± 27.36	79.91 ± 31.43	0.194	0.787
Stone density (1000 HU)	883.60 ± 243.55	960.66 ± 225.01	−4.88	0.649
Stone diameter (mm)	15.65 + 2.95	17.15 ± 2.94	−3.33	0.759
Site of stones (left/right)	25/20	24/21	1.216	0.270
Preoperative infection (yes/no)	8/45	11/45	2.719	0.35
History of SWL treatment (yes/no)	15/45	13/45	0.386	0.535

Data are presented as means ± standard deviations or numbers.

BMI = body mass index; PCNL = percutaneous nephrolithotomy; SWL = extracorporeal shockwave lithotripsy; URSL = ureteroscopic lithotripsy.

Overall, the length of hospital stay was significantly longer in the PCNL group than that in the URSL group, but the surgical duration was significantly shorter and SFR was significantly higher in the PCNL group than in the URSL group (p < 0.05). No secondary procedures such as second look PCNL or URSL were performed in this series. There was a significant difference in the total cost of treatment between the two groups, with a much lower cost in the PCNL group (Table 2).

Table 2.

Intraoperative and Postoperative Data According to Patients' Group

Parameter	URSL group, N = 45	PCNL group, N = 45	p
Operation time (minutes)	73.46 ± 27.12	53.69 ± 25.07	0.000
Length of hospital stay (days)	3.68 ± 2.70	6.39 ± 3.34	0.000
SFR	31 (68.9)	42 (93.33)	0.000
Complication rate	9 (20.0)	4 (8.9)	0.037
Total cost of treatment (US $)	3901.45 ± 1069.46	1678.61 ± 714.86	0.000

Data are presented as means ± standard deviations or numbers and proportions.

SFR = stone-free rate.

Based on the modified Clavien grading standards, there was a significant difference in complication rates between the two groups regarding Clavien grade I, II, or III complications (Table 3). There were five cases with grade I complications, all of which had postoperative renal colic that was treated with analgesics (three in the URSL group and two in the PCNL group), Postoperative infection occurred in six patients in the URSL group, and all the patients were effectively treated with antibiotics. Serious postoperative hematuria occurred in one patient after PCNL, and the patient was treated with embolization after failure to control the bleeding (Table 3).

Table 3.

Complications Classified According to the Modified Clavien System

Parameter	URSL group, N = 45	PCNL group, N = 45	p
Grade 1
Postoperative renal colic	3	2	—
Transient fever <38°C	—	—	—
Grade 2
Bleeding requiring transfusion	—	1	—
Nonseptic infections requiring additional antibiotics	6	—
Grade 3
Grade 3a
Bleeding requiring embolization	—	1
Grade 4	—	—	—
Grade 5	—	—	—
Overall, N (%)	9 (20.0)	4 (8.9)	0.037

Discussion

The choice of management for complicated impacted proximal ureteral calculi has been controversial for a long time, but the goal is for patients to be completely stone-free and to avoid complications. Some clinical factors may play an important role, in addition to the experience of the surgeon.^15,16

URSL mainly includes semirigid ureteroscopy and flexible ureteroscopy. URSL is generally safe and provides rapid postoperative recovery, but URSL also has significant disadvantages. Poor irrigation control leads to stone fragments being flushed back into the renal collection system, which might lead to a lower SFR. The SFR in our study was only 68.9% (31/45), but fortunately, most URSL patients did not need a long period of hospital stay. The hospital time in URSL group (3.68 ± 2.70 days) was significantly shorter than that in PCNL group (6.39 ± 3.34 days) in our study.

Usually, URSL has a lower risk of serious complications compared to other surgeries, and all the complications were in Grades 1 and 2 in our study. However, severe cases of urinary tract infection might lead to urosepsis and even septic shock.¹⁵ The main mechanism of infection is high intraoperative irrigation pressure, resulting in the reflux of bacterial endotoxins into the circulation system.^17,18 Study has shown that the use of UAS can significantly decrease introrenal pressure during URSL.¹⁸ Holmium laser lithotripsy increases the risk of ureteral stricture.¹⁹ Fam et al reported that the incidence of ureteral stricture after the operation is 3% to 24%.²⁰ Ureteral stricture can be caused by thermal damage during holmium laser lithotripsy. The thermal effect can damage the epithelial structure and blood supply of the ureter wall.²¹ However, no patients with ureteral stricture after URSL were identified in the present study.

The advantage of PCNL lies in its high SFR, which was 93.33% (42) in this study; Gdor et al found that the success rate of ureteroscopy in the treatment of impacted ureter stones is only 56%.²² PCNL does have several advantages in both the initial and overall stone clearance efficiency compared to URSL. The study has shown that the adjuvant surgery rate of URSL is much higher than that of PCNL.¹⁷ PCNL also has many serious complications such as damage to the adjacent organs, hemorrhage, and severe postoperative infections.^23

–26

To achieve better surgical outcomes, the choice of management is quite important. Based on the findings from the previous studies, five preoperative stone-related high-risk factors (stone diameter, stone hardness, history of the previous lithotripsy, degree of hydronephrosis, and infection) were selected for evaluation and analysis in the present study. After scoring and grouping preoperative high-risk factors of the stones, the patients were classified as complicated cases (score ≥3 points) group. In the complicated cases, the operation time and complication rate of URSL significantly increased, whereas SFR was quite low. These findings indicate that compared with PCNL, the efficacy of URSL in complicated cases is much lower.

However, the present study has some limitations. First, the study was a retrospective analysis that was conducted among patients enrolled at a single center. Second, the number of patients included was relatively small. A prospective, multicenter randomized controlled trial will be expected in the future to validate the scoring system. Nevertheless, this is the first scoring standard used for the complicated impacted proximal ureteral calculi. These findings assist in guiding the treatment choice of different surgical approaches; urologists can make personalized predictions for patients through this easy-to-use scoring standard.

Conclusion

In conclusion, for complicated impacted proximal ureteral calculi, PCNL had a better SFR and higher surgical efficacy, whereas URSL had a relatively shorter perioperative period, but a much lower initial SFR. Thus, when choosing a better treatment method for complicated impacted proximal ureteral calculi, we believe that PCNL is the preferred choice over URSL. We hope that these findings may assist in the future decision-making strategy of guiding the treatment choice based on a new scoring standard for patients with complicated impacted proximal ureteral calculi.

Footnotes

Acknowledgments

This article has previously been submitted as a preprint to Research Square. The DOI is https://doi.org/10.21203/rs.3.rs-2108575/v1.

Authors' Contributions

Y.S. designed the study and conducted the trial. L.Z. wrote the article. X.F. analyzed the data. L.Z. and Z.J. revised the article. All authors have read and approved the article.

Availability of Data and Materials

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Author Disclosure Statement

The authors declare that they have no competing interests.

Funding Information

No funding was received for this article.

Abbreviations Used

References

Zeng

, Mai

, Xia

, et al. Prevalence of kidney stones in China: An ultrasonography based cross-sectional study. BJU Int, 2017; 120(1):109–116.

de la Rosette

, Denstedt

, Geavlete

, et al. The clinical research office of the endourological society ureteroscopy global study: Indications, complications, and outcomes in 11,885 patients. J Endourol, 2014; 28(2):131–139.

Shivakumar

, Nantha Kumar

, Joshi

. The impact of early COVID-19 pandemic on the presentation and management of urinary calculi across the globe: A systematic review. J Endourol, 2022; 36(9):1255–1264.

Geraghty

, Davis

, Tzelves

, et al. Best practice in interventional management of urolithiasis: An update from the European Association of Urology Guidelines Panel for Urolithiasis 2022. Eur Urol Focus, 2022; 1:S2405-4569(22)00144-4.

Lai

, Jiao

, Jiang

, et al. Comparing different kidney stone scoring systems for predicting percutaneous nephrolithotomy outcomes: A multicenter retrospective cohort study. Int J Surg, 2020; 81:55–60.

, Duan

, Chen

, et al. Ureteroscopic lithotripsy versus laparoscopic ureterolithotomy or percutaneous nephrolithotomy in the management of large proximal ureteral stones: A systematic review and meta-analysis. Urol Int, 2017; 99(3):308–319.

Bozkurt

, Yonguc

, Arslan

, et al. Minimally invasive surgical treatment for large impacted upper ureteral stones: Ureteroscopic lithotripsy or percutaneous nephrolithotomy?. Can Urol Assoc J. 2015; 9(3–4):E122–E125.

, Na

, Li

, et al. Percutaneous nephrolithotomy versus ureteroscopic lithotomy for large (>15mm) impacted upper ureteral stones in different locations: Is the upper border of the fourth lumbar vertebra a good indication for choice of management method?. J Endourol, 2013; 27(9):1120–1125.

Guler

, Erbin

, Kafkasli

, et al. Factors affecting success in the treatment of proximal ureteral stones larger than 1cm with extracorporeal shockwave lithotripsy in adult patients. Urolithiasis, 2020; 49(1):51–56.

10.

Kokov

, Manka

, Beck

, et al. Only size matters in stone patients: Computed tomography controlled stone-free rates after mini-percutaneous nephrolithotomy. Urol Int, 2019; 103(2):166–171.

11.

Gucuk

, Yilmaz

, Gucuk

, et al. Are stone density and location useful parameters that can determine the endourological surgical technique for kidney stones that are smaller than 2 cm? A prospective randomized controlled trial. Urol J, 2019; 16(3):236–241.

12.

Yuruk

, Tefekli

, Sari

, et al. Does previous extracorporeal shock wave lithotripsy affect the performance and outcome of percutaneous nephrolithotomy?. J Urol, 2009; 181(2):663–667.

13.

Kadihasanoglu

, Erkan

, Yucetas

, et al. Does preoperative hydronephrosis affect the stone-free rate of micro-percutaneous nephrolithotomy?. Arch Esp Urol, 2019; 72(4):406–414.

14.

Haas

, Li

, Hyams

, et al. Delayed decompression of obstructing stones with urinary tract infection is associated with increased odds of death. J Urol, 2020; 204(6):1256–1262.

15.

Turk

, Petrik

, Sarica

, et al. EAU guidelines on interventional treatment for urolithiasis. Eur Urol, 2016; 69(3):475–482.

16.

Kurkar

, Elderwy

, Osman

, et al. Predictors of successful emergency shock wave lithotripsy for acute renal colic. Urolithiasis, 2022; 50(4):481–485.

17.

Chen

, Wu

, Shee

, et al. Holmium:YAG Lasertripsy with semirigid ureterorenoscope for upper-ureteral stones >2cm. J Endourol, 2015; 19(7):780–784.

18.

Osther

PJS

. Risks of flexible ureterorenoscopy: Pathophysiology and prevention. Urolithiasis, 2018; 46(1):59–67.

19.

, Pan

, Weng

, et al. A prospective randomized trial comparing pneumatic lithotripsy and holmium laser for management of middle and distal ureteral calculi. J Endourol, 2015; 29(8):883–887.

20.

Fam

, Singam

, Ho

, et al. Ureteral stricture formation after ureteroscope treatment of impacted calculi: A prospective study. Korean J Urol, 2015; 56(1):63–67.

21.

, Xu

, Wang

, et al. Ureteral stricture formation after removal of proximal ureteral stone: Retroperitoneal laparoscopic ureterolithotomy versus ureteroscopy with holmium: YAG laser lithotripsy. PeerJ, 2017; 5:e3483.

22.

Gdor

, Gabr

, Faerber

, et al. Success of laser endoureterotomy of ureteral strictures associated with ureteral stones is related to stone impaction. J Endourol, 2008; 22(11):2507–2511.

23.

Wollin

, Preminger

. Percutaneous nephrolithotomy: Complications and how to deal with them. Urolithiasis, 2018; 46(1):87–97.

24.

Zhang

, Fei

, Song

. The clinical efficacy of novel vacuum suction ureteroscopic lithotripsy in the treatment of upper ureteral calculi. World J Urol, 2021; 39(11):4261–4265.

25.

Tian

, Yang

, Luo

, Wang

, Sun

. Initial prospective study of ambulatory mPCNL on upper urinary tract calculi. Urol J, 2020; 17(1):14–18.

26.

Xun

, Wang

, Hu

, et al. Tubeless versus standard percutaneous nephrolithotomy: An update meta-analysis. BMC Urol, 2017; 17(1):102.