Assessment of Risk Factors of Postoperative Urosepsis in Patients Undergoing Unilateral Uretereoenoscopy and Lithoclast

The most common urological problem remains to be the urinary stone issue yet it has been known since decades. Today, the epidemiology, risk factors, and mechanisms of stone formation are well-known, and even geographical, climatic, ethnic, nutritional, and genetic factors play a role in the etiology. Urosepsis is sepsis that is induced by urinary tract, lower urinary tract, and bladder infections, or pyelonephritis, or upper urinary tract, and kidney infections. Urogenital tract is the source of nearly 25 percent of sepsis cases. Urolithiasis is still becoming increasingly common over the world. The upper urinary system is the most affected by urolithiasis, and the prevalence of the disease is 75.08% and 13.62% in the kidneys and ureters, respectively, but 9.56% of the stones are found at the vesicoureteral junction.

URSL is a minimally invasive, low-risk, approved procedure in the treatment of urolithiasis that has a stone-free rate between 77% to 97.5. Nevertheless, other patients acquire urinary tract infection (UTI) post-URSL procedure, which later results in urosepsis and subsequently to septic shock with severe organ dysfunction and even death. Hence, timely diagnosis of urosepsis is obligatory to provide efficient and timely treatment. Therefore, the knowledge of the risk factors associated with urosepsis can be used to recognize the high-risk patients who are vulnerable to this risky outcome. Numerous studies have examined the complications after URSL and identified risk factors of post-URSL infectious complications, one of which is urosepsis. Kaczmarek K 2024 et al revealed the risk factors, older age (>50), BMI > 30 kg/m² (24.68%), male gender (60.17%), hypertension (48.48%), diabetic mellitus (16.9%), history of urosepsis (4.8%), hydronephrosis (22.9%), DJ/PCN (19.5%), the number of stones (multiple) (21.2%), the maximum diameter of calculi >10 (19.5%), and an operation time more than 60 minutes (12.1%).

Objective

To determine the frequency of different risk factors associated with postoperative urosepsis in patients undergoing unilateral Ureterorenoscopy and Lithoclast.

This was a Retrospective cohort study conducted at the Department of Urology, Balochistan Institute of Nephro-Urology, Quetta, a tertiary care center providing specialized urological services, from 20 May 2025 to 20 August 2025. The sample size was calculated using WHO calculator based on a previous study by Kaczmarek et al. (2023), which reported the frequency of different risk factors ranging from 5% to 60%. A total of 292 patients were required to estimate the lowest expected proportion (5%) with a 2.5% margin of error and 95% confidence interval. A non-probability consecutive sampling strategy was employed to identify all the eligible patients who presented at the time of study. The study included patients of both sexes between the ages of 30 and 80 years diagnosed with postoperative urosepsis after having undergone unilateral ureterorenoscopy with the use of lithoclast. Clinically verified patients that did not have upper urinary tract stones or calculous pyonephrosis were excluded. Moreover, patients whose systemic diseases were severe and who had a constant risk of death were also not included to prevent confounding. All the successive eligible patients who reported to the outpatient department were enrolled after the approval of both the College of Physicians and Surgeons Pakistan (CPSP) and the institutional ethical review committee. Informed consent was taken before inclusion into the study. The collection of data was done through a predesigned proforma. Demographic data were noted such as age, sex, body mass index, residential status, education level, and socioeconomic status. Hypertension, diabetes mellitus, history of urosepsis, presence of hydronephrosis, preoperative drainage (DJ stent or percutaneous nephrostomy), the number of stones, the largest calculi, calculi location, and laterality, and the operating time were also recorded. Patient data were recorded at a single point following the development of postoperative urosepsis after ureterorenoscopy. Clinical, demographic, and operative details were obtained from hospital records and documented using a predesigned proforma. No longitudinal follow-up was conducted, and all variables were assessed during the postoperative hospital stay at the time of diagnosis. In patients suspected of postoperative urosepsis, appropriate clinical samples (urine and/or blood) were collected under aseptic conditions at the time of diagnosis and sent to the hospital laboratory for culture and sensitivity testing. Identification of causative pathogens was performed using standard microbiological techniques. In cases where cultures had already been performed as part of routine clinical care, results were retrieved from hospital records and documented in the study proforma. Statistical Package of the Social Sciences (SPSS) version 19 was used to enter and analyze the data. Kolmogorov-Smirnov test and Q-Q plots were used to test the normality of the continuous variables. The continuous variables (age, weight, height, body mass index, maximum stone diameter, and operative time) were reported as mean ± standard deviation when normally distributed, and as median and interquartile range when not. Categorical variables such as gender, residence, education level, socioeconomic status, causative pathogens, and risk factors associated (age >50 years, BMI >30 kg/m 2, hypertension, diabetes mellitus, history of urosepsis, hydronephrosis, DJ/PCN, number of stones, stone size and location, laterality and time of operation) were presented as frequencies The stratification was done to control effects modifying factors including residence, education level, and socioeconomic status. Chi-square test or Fisher exact test was used where necessary, post-stratification. Binary logistic regression analysis was performed to identify independent predictors of postoperative urosepsis. A p-value ≤0.05 was considered statistically significant.

Strictly speaking, postoperative urosepsis is a severe, potentially fatal complication of the treatment of urolithiasis with ureterorenoscopy and lithoclast. It is necessary to identify the risk factors that relate to this complication to enhance the perioperative management and decrease morbidity. The current research compared the demographic, clinical, and stone-related variables among the patients that developed postoperative urosepsis following ureterorenoscopy. The results of the current research showed that a number of patient-related and  procedural factors can potentially lead to the

development of postoperative urosepsis.

The median age of the patients in the present research was 54.41 +14.37 years, which means that middle-aged and older patients were more likely to develop postoperative urosepsis. The presence of comorbid conditions and reduced immune response due to increased age have also been demonstrated in previous research as increasing age is linked to an increased risk of postoperative infectious complications. Previous research indicated that patients who were above 50 years were at a high risk of urosepsis development after undergoing ureteroscopic procedures. These findings confirm the findings of the current study, which is that age is still a significant risk factor in the development of postoperative infections.

Another critical factor, which was assessed in the current study, was body mass index. The average BMI of the patients was 29.79 +/- 6.26 kg/m 2 and this suggests that a significant number of patients were obese or overweight. Impaired immune response, heightened inflammatory response and extended operating time has been linked to obesity and may predispose the patient to postoperative infection. According to previous research works, patients with BMI beyond 30kg/m 2 are more likely to develop postoperative urosepsis after a ureteroscopy.

Such comorbidities like hypertension and diabetes mellitus were also common among the patients in this study. Forty-eight point three percent of the patients had hypertension and 48.6 percent of the study population had diabetes mellitus. Diabetes mellitus is a clearly known risk factor of infection due to compromised immune response and poor glycemic control. Some of the earlier researches have found a significant correlation between postoperative infectious complications and diabetes mellitus in patients who have undergone endourological procedures.

Hydronephrosis was identified in 110 (37.7%) of the patients in the present study. The condition of hydronephrosis might also contribute to the risk of infection because of the stasis of urine and its blockage leading to the possibility of bacteria growth in the urinary tract. Similar findings have been noted in the previous studies, which have found hydronephrosis to be a major predictor of postoperative urosepsis following ureteroscopic lithotripsy.

There were also some stone related factors that contributed significantly to the emergence of postoperative complications. In the study, there were several stones in 46.2 percent of the patients with most of them being found in the ureter and kidney. The availability of more than one stone can enhance the complexity of the operation and shorten the duration of the surgery which can raise the risk of contamination. Stone location and size have also been reported as important predictors of postoperative complications in previous studies.

The other important factor related to postoperative urosepsis was the operative time. The average length of stay of operations in the current study was 70.05 +29.47 minutes and over 50 percent of the operations took more than 60 minutes. The long duration of the operation can lead to an increased risk of infection since more manipulation of the urinary tract and exposure to the possible bacteria contamination can occur. Another study conducted previously also showed that procedures lasting over 60 minutes are associated with a higher risk of infectious complications after surgery.

In the current case, microbiological analysis showed that Pseudomonas species were the most prevalent pathogen in the development of postoperative urosepsis (22.6%). This was succeeded by Klebsiella, Escherichia coli, Proteus species, and others. The same microbial patterns are reported in the literature, where gram-negative bacteria were identified as the most common pathogens causing urinary tract infections and urosepsis.

Limitations

There are several limitations to this study, which should be kept in mind when interpreting the results. To begin with, the research was conducted in one tertiary care facility and may not be applicable to other health care facilities or populations. Second, the study design is cross-sectional, limiting the ability to determine causal relationships between the identified risk factors and the emergence of postoperative urosepsis. Third, despite evaluating several demographic and clinical variables, other potential variables, including preoperative urine culture results, antibiotic prophylaxis, the surgeon's experience, and intraoperative irrigation pressure, were not addressed. Moreover, the research was based on hospital-documented information, which can be influenced by reporting bias or partial recording. It has been suggested that future multicenter research should include larger sample sizes and be prospective to further confirm these results and help determine better predictors of postoperative urosepsis after ureteroscopic surgery.

It is concluded that several demographic, clinical, and procedural factors are associated with the development of postoperative urosepsis in patients undergoing ureterorenoscopy and lithoclast for urolithiasis. Advanced age, higher body mass index, presence of comorbid conditions such as hypertension and diabetes mellitus, hydronephrosis, multiple stones, and prolonged operative time were identified as important risk factors. Gram-negative organisms, particularly Pseudomonas and Klebsiella species, were the most common pathogens causing postoperative urosepsis.

1.    Wagner CA. Etiopathogenic factors of urolithiasis. Factores etiopatogénicos de la urolitiasis. Arch Esp Urol. 2021;74:16-23.

2.    Björck V, Pählman LI, Boldesson M, Petersson AC, Kander T. Morbidity and mortality in critically ill patients with invasive group A streptococcus infection: an observational study. Crit Care. 2020;24(1):302.

3.    Shimoni Z, Salah M, Kasem A, Hermush V, Froom P. Bacterial resistance to Cephalosporin Treatment in Elderly Stable Patients Hospitalized With a Urinary Tract Infection. Am J Med Sci. 2020;360(3):243-7.

4.    De Coninck V, Skolarikos A, Juliebø-Jones P, Joris M, Traxer O, Keller EX. Advancements in stone classification: unveiling the beauty of urolithiasis. World Journal of Urology. 2024 Jan 20;42(1):46.

5.    Tan S, Yuan D, Shi H, Chen W, Zhu S, Yan B, Sun F, Jiang K, Zhu J. Prevalence of urolithiasis in China: a systematic review and meta-analysis. BJU International. 2024;133(1):34-43.

6.    Smigielska A, Skrzypek P, Pańczyk-Tomaszewska M. Epidemiology and types of urolithiasis. Pediatr Med Rodz. 2019;15:22-5.

7.    Faridi M, Singh K. Preliminary study of prevalence of urolithiasis in North-Eastern city of India. J Fam Med Prim Care. 2020;9:5939-43.

8.    Kaczmarek K, Jankowska M, Kalembkiewicz J, Kienitz J, Uchowku O, Lemiński A, Slojewski M. Assessment of the incidence and risk factors of postoperative urosepsis in patients undergoing ureteroscopic lithotripsy. Cent European J Urol. 2024;77(1):122.

9.    Itami Y, Miyake M, Owari T, Iwamoto T, Gotoh D, Momose H, Fujimoto K, Hirao S. Optimal timing of ureteroscopic lithotripsy after the initial drainage treatment and risk factors for postoperative febrile urinary tract infection in patients with obstructive pyelonephritis: a retrospective study. BMC Urol. 2021;21:11.

10.  Chugh S, Pietropaolo A, Montanari E, Sarica K, Somani BK. Predictors of urinary infections and urosepsis after ureteroscopy for stone disease: a systematic review from EAU section of urolithiasis (EULIS). Curr Urol Rep. 2020;21:16.

11.  Bhojani N, Miller LE, Bhattacharya S, Cutone B, Chew BH. Risk factors for urosepsis after ureteroscopy for stone disease: A systematic review with meta-analysis. J Endourol. 2015;29:591-100.

12.  Ma YC, Jian ZY, Yuan C, Li H, Wang KJ. Risk factors of infectious complications after ureteroscopy: A systematic review and meta-analysis based on adjusted effect estimate. Surg Infect. 2020;21:811-822.

13.  Liang X, Huang J, Xing M, et al. Risk factors and outcomes of urosepsis in patients with calculous pyonephrosis receiving surgical intervention: A single-center retrospective study. BMC Anesthesiol. 2019;19:61.

14.  Kaczmarek K, Jankowska M, Kalembkiewicz J, Kienitz J, Chukwu O, Lemiński A, Słojewski M. Assessment of the incidence and risk factors of postoperative urosepsis in patients undergoing ureteroscopic lithotripsy. Cent European J Urol. 2024;77(1):122-128. doi: 10.5173/ceju.2023.167. Epub 2024 Jan 8. PMID: 38645806; PMCID: PMC11032028.

15.  Dai L, Xiang J, Liu X, Wen X, Tan L and Zhang J (2025) Risk factors for urosepsis following ureteroscopic lithotripsy: a systematic review and meta-analysis. Front. Surg. 12:1603311. doi: 10.3389/fsurg.2025.1603311

16.  Kaczmarek K, Jankowska M, Kalembkiewicz J, Kienitz J, Chukwu O, Lemiński A, Słojewski M. Assessment of the incidence and risk factors of postoperative urosepsis in patients undergoing ureteroscopic lithotripsy. Cent European J Urol. 2024;77(1):122-128. doi: 10.5173/ceju.2023.167. Epub 2024 Jan 8. PMID: 38645806; PMCID: PMC11032028.

17.  Juszczak K, Dybowski B, Holecki M, Hryniewicz W, Klimek H, Kłoda K, Sieroszewski P, Drewa T. Summary of guidelines from the Polish Urological Association, Polish Society of Gynaecologists and Obstetricians, and Polish Society of Family Medicine on the diagnosis, therapy, and management of community-acquired lower urinary tract infections. Cent European J Urol. 2024;77(3):520-527. doi: 10.5173/ceju.2024.01.Guid. Epub 2024 Oct 29. PMID: 40115487; PMCID: PMC11921942.

18.  Hu Y, Wang X, Chen Y, Li J, Zhong Y, Zhu F, Yuan Y, Ye J, Yang F. Pathogen distribution and antibiotic sensitivity analysis in urosepsis associated with urinary stones: A retrospective observational study. Medicine (Baltimore). 2025 Jun 27;104(26):e43079. doi: 10.1097/MD.0000000000043079. PMID: 40587736; PMCID: PMC12212809.

19.  Shaikh N, Momin U, Atef SA, Al-Musalmani M, Ansari A. Community acquired urosepsis: a surgical intensive care experience. Qatar Med J. 2020;2020:8.

20.         Weinstein MP, Lewis JN. The Clinical and Laboratory Standards Institute Subcommittee on antimicrobial susceptibility testing: background, organization, functions, and processes. J Clin Microbiol. 2020;58:e01864-19