Facteurs de risque du syndrome de réponse inflammatoire systémique après néphrolithotomie percutanée

25 octobre 2018

Auteurs : Z. He, F. Tang, H. Lei, Y. Chen, G. Zeng
Référence : Prog Urol, 2018, 12, 28, 582-587



Urinary stone is one of the common diseases in the Department of urology. It has been reported that the prevalence of urinary stones is about 5-15% and its recurrence rates after 10 years up to 50% [1, 2]. The incidence of urinary stone is constantly increasing in industrialized countries and the prevalence of urinary stone was 10% in France [3]. Percutaneous nephrolithotomy (PCNL) is the main method of removing renal calculi, particularly for the patients with burden of large or complex stones. Because of the small trauma, quick recovery and a higher rate of stone clearance, PCNL has become the first choice for treatment of complicated upper urinary tract calculi. However, relatively higher postoperative complication rates were also reported. Systemic inflammatory response syndrome is one of the frequent complications after PCNL. If not well controlled in time, Systemic inflammatory response syndrome can be further developed into a source of urinary sepsis, and even lead to multiple organ dysfunction syndrome (MODS), which may threaten the lives of patients. The postoperative SIRS is associated with several preoperative risk factors such as operative time, Staghorn calculi and diabetes [4]. The Staghorn calculi are stones that occupy renal pelvis and branch into several or all of the calices [5]. However, there are few reports about the correlation between the urinary sediment microscopy WBC and SIRS after the PCNL.

In this study, our objective was to evaluate the association between urinary sediment microscopy WBC and postoperative SIRS.

Patients and methods


In this retrospective study, all patients with renal calculi or upper urethral calculi that had undergone PCNL from January 2014 to July 2016 in the Minimally Invasive Surgery Center (First Affiliated hospital of Guangzhou Medical University) were enrolled. All the operations were performed in standard procedure by experienced urologists. Patients with tumor, blood disease, urinary tract tuberculosis, hyperthyroidism and juvenile patients were excluded from the study. A total of 1030 patients who had met the inclusion and exclusion criteria were eligible for this study. All the participants had agreed to take part in this study. The study was approved by the Ethics Committee of the First Affiliated Hospital of Guangzhou Medical University. Preoperative factors including the age, sex, BMI, Surgery time, Serun creatinine (SCr), midstream urine culture, the urinary sediment microscopy WBC (+∼++++), Staghorn calculi and diabetes were recorded. All patients with preoperative positive urine cultures were treated with at least one week of appropriate antibiotics therapy. Based on urine culture and sensitivity results, surgery was performed when urine became sterile. The antibiotic would also be used prophylactically before surgery. Patients would receive one dose of preventive cefathiamidine 30minutes before surgery. An appropriate grading of SIRS observed according to the Clavien Score based on the management needed within a month after the operation [6].

Evaluation and statistical analysis

According to criteria established by the American College of Chest Physicians (ACCP) and the Society of Critical Care Medicine (SCCM) in 2001, SIRS was diagnosed in patients who met two or more of the following clinical findings: body temperature>38°C or<36°C; (2) heart rate>90bpm; (3) respiratory rate>20 breaths/min or PaCO2<32mmHg; (4) white blood cell count>12,000cells/μl or<4000cells/μl [7]. SPSS (R) 16.0 statistical software was used in this study for statistical analysis. Date with normal distribution were recorded as mean±standard deviation (SD). Univariate analyses were performed by using Chi2 and/or univariate factor logistics analysis, whereas continuous variables were compared by using independent sample t -tests in both groups. The relative risk (odds ratio, OR) was used in a multivariable logistic regression to determine risk factors for SIRS. Each statistical test was two-sided and statistical significance was set at a P -value of<0.05.


A total of 1030 patients who underwent PCNL were included in this retrospective study. Table 1 listed the patients' demographics and stone characteristics. The average age of 1030 patients was 52.05±11.94 years and the mean of serum creatinine was 107.74±(69.31)μmol/L. Among the 1030 patients, 571 (55.44%) were male and 459 (44.56%) were female (Table 1). The average operation time was 153.05±(45.60)minutes. The preoperative positive midstream urine culture was noted in 179 (17.38%) patients and listed as follows: Gram-negative bacteria were found in 143 cases (13.88%), Gram-positive bacteria were found in 33 cases (3.20%) and Fungus were found in 3 cases (0.29%). The urinary sediment microscopy WBC (+∼++++) was noted in 298 (28.93%) patients. In the present study, there were 108 cases (10.49%) of SIRS found in 1030 patients, in which 73 cases were categorized as Clavien score 2, 29 cases were categorized as Clavien score 3A, and 6 cases were categorized as Clavien score 4A. All patients recovered without sequelae.

In the univariate test analysis (Table 2), significant correlation between SIRS and four factors was noted: sex of the patient (P =0.015), Staghorn calculi (P <0.001), the urinary sediment microscopy WBC (+) (P <0.001), the urinary sediment microscopy WBC (++) (P <0.001), the urinary sediment microscopy WBC (+++) (P =0.009), the urinary sediment microscopy WBC (++++) (P =0.045), and Gram-negative bacteria (P <0.001). There was no significant difference in age, BMI, Serun creatinine, operation time, diabetes and SIRS (P >0.05).

In the multivariate logistic regression analysis, Staghorn calculi [OR=10.457, 95% confidence interval (CI)=1.312-3.092, P =0.01], Gram-negative bacteria [OR=3.550,95% confidence interval (CI)=2.205-5.715, P <0.001] and the urinary sediment microscopy WBC (+∼++++) [OR=2.702, 95% confidence interval (CI)=1.604-4.551, P <0.001], were found independently associated with postoperative SIRS (Table 3). Based on the OR and 95% CI values gained from the multivariable logistic regression analysis, these three risk factors promoted the development of SIRS after PCNL.

The predictive equation from logistic regression analysis results were as follows:

Risk index=−2.860+1.009X[The urinary sediment microscopy WBC (+∼++++)]+1.267X(Gram-negative bacteria)+0.69X(Staghorn calculi)


Percutaneous nephrolithotomy is a safe and effective method, which is recognized as the gold standard treatment for kidney stones regardless of age [8], and considered as the first choice for the treatment of complex upper urinary tract calculi [9]. However, the rate of its complications can be up to 8-38% [10]. The most common complications were bleeding, infection and injury of adjacent organs during the establishment of operating tracts and lithotripsy. SIRS is one of the most common complications after PCNL. This complication is a systemic inflammatory response that will lead to self-destroying damage to the body. Such self-destroying damage is caused by infectious or non-infectious factors. In our study, postoperative complication rates of SIRS were 10.69%, and this result was similar to previous studies (11.2-22%) [11, 12].

The clinical data of 1030 patients were collected and analyzed for this retrospective study. As showed in results above, factors including the gender, Staghorn calculi, preoperative urine culture for the occurrence of Gram-negative bacteria and the urinary sediment microscopy WBC were associated with development of SIRS after PCNL. Multivariate logistic regression analysis results showed that the commodity of Staghorn calculi, the urinary sediment microscopy WBC and preoperative positive urine culture for Gram-negative bacteria were independently related to postoperative SIRS, whereas the results of our study showed that age, BMI, operation time and serum albumin were irrelevant to SIRS, which was in agreement with prior studies [13, 14, 15]. A significant association between diabetes and the operation time and SIRS was not observed from our study, which conflicted with prior studies [4, 16, 17]. The use of the appropriate antibiotics can control infection and prevent the occurrence of SIRS effectively. All the appropriate antibiotics were selected according to the results of urinary sediment microscopy WBC and preoperative positive urine culture.

Women are more susceptible to infection because of their special urinary tract anatomy. In addition, perineal cleaning, postmenopausal estrogen, atrophic vaginitis are also related to the cause of urinary tract infection [18, 19]. The positive rate of urine culture of female patients was higher than that of male patients in this study, single factor analysis results showed that the female was significantly correlated with SIRS (P =0.01), but the results of multivariate logistics regression analysis indicated that women were not independent risk factors. This is similar to the results of Ali Roushani [14].

Most Staghorn calculi contain magnesium ammonium phosphate, calcium carbonate, and apatite, which are infectious stones. But some of them are metabolic stones, such as cystine stones or uric acid stones. Our study suggests that Staghorn stone is an independent risk factor for SIRS, which may be related to its components, and the increasing operation time, more operating channels will increase the probability of postoperative SIRS.

Urinary tract infection is one of the important factors leading to SIRS after PCNL. Previous studies have demonstrated that positive urine culture is a risk factor for SIRS after PCNL [20, 21]. 187 patients with positive urine culture were enrolled in the study. Among these patients, 46 cases of them suffered from SIRS (24.6%). There were 149 cases found Gram-negative bacteria in the preoperative urine culture, among which the most common bacteria was Escherichia coli , accounting for 53.5%, followed by Proteus which is account for 8.6%. Our results reveal that positive urine culture for Gram-negative bacteria is an independent risk factor for SIRS. Therefore, antibiotics should be used to control infection in time to prevent the occurrence of postoperative SIRS when patients with positive urine culture, especially urine culture for Gram-negative bacteria.

Microscopic examination of urinary sediment is not an indispensable reference index for the diagnosis of urinary tract infection. In this study, 302 patients had positive urine white blood cell, accounting for 28.33%. Logistics single factor analysis results showed a positive correlation between urinary sediment microscopic examination (+, ++, +++, ++++) and SIRS after operation in patients with PCNL. The research results revealed that the positive urinary sediment examination was an independent risk factor for SIRS after PCNL. But the European Association of Urology (EAU) guidelines on preoperative antibiotic do not explicitly point out that, according to the microscopic examination of urine sediment positive (+, ++, +++, ++++) to give the corresponding anti infection after surgery. Although Korets R. [22] approve that the use of antibiotics cannot completely avoid the occurrence of postoperative SIRS, it can significantly reduce the incidence of bacteremia and promote the recovery of SIRS and shorten the length of hospitalization. Therefore, it is significant to choose sensitive antibiotics depending on the preoperative results of urine culture and extend the days of antibiotic use according to the degree of positive urine sediment microscopy, so as to prevent patients from SIRS that contributed to their recovery.

Because of the retrospective nature of the study, there are inevitable limitations of our study. More risk factors are not included in this research work such as stone size, C-reactive protein and so on. Most research report that the stone size was found significantly associated with the development of SIRS [23, 24]. But B. Lojanapiwat et al. [25] think that stone size do not have significant relativity with postoperative SIRS. Therefore, more studies with larger sample size and further high quality randomized trials are needed to confirm this finding. C-reactive protein (CRP) is an acute phase reactant. Vishnu et al. report that CRP was predictive for the development of SIRS after PCNL [26]. However, more research is needed to confirm this finding. Because of the large samples and the difficulty of data collection, more risk factors are not taken into consideration. To better understand our current findings and identify new risk factors, further prospective study based on multiple centers is needed.


The study showed that gender, Gram-negative bacteria and microscopic examination of urinary sediment were positive factors in SIRS after PCNL. Multivariate analysis revealed that the Staghorn calculi, Gram-negative bacteria and urinary sediment microscopy were independent risk factors for SIRS after PCNL, which should cause the clinician's attention. Therefore, it is suggested that preoperative routine urine and urine routine examination help to discover and control urinary tract infection timely, which are significant to prevent postoperative SIRS.

Ethical statements

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors. For this type of study, formal consent is not required.


This study was supported by Guangzhou Science and Technology Project of China (No. 201510010272), Science and Technology Planning Project of Guangdong Province (grant no.2017B030314108).

Disclosure of interest

The authors declare that they have no competing interest.

Table 1 - Patient demographics and stone characteristics (n =1030).
Age (year), Mean (SD)  52.05±11.94 
BMI (Kg/m2), Mean (SD)  23.68±(3.87) 
Surgery time (min), Mean (SD)  153.05±(45.60) 
Serun creatinine (μmol/L), Mean (SD)  107.74±(69.31) 
Male, n (%)  571 (55.44) 
Female, n (%)  459 (44.56) 
The urinary sediment microscopy WBC (+∼++++)a, n (%)  298 (28.93) 
The urinary sediment microscopy WBC (+), n (%)  112 (10.87) 
The urinary sediment microscopy WBC (++), n (%)  97 (9.42) 
The urinary sediment microscopy WBC (+++), n (%)  66 (6.80) 
The urinary sediment microscopy WBC (++++), n (%)  23 (2.23) 
Bacterial species detected in midstream urine, n (%)  179 (17.38) 
Gram-negative bacteria, n (%)  143 (13.88) 
Gram-positive bacteria, n (%)  33 (3.20) 
Fungus, n (%)  3 (0.29) 
Staghorn calculi, n (%)  335 (32.52) 
Diabetes, n (%)  64 (6.21) 

Légende :
BMI: body mass index.

The urinary sediment microscopy WBC=At high magnification, urine sediment white blood cell count.The urinary sediment microscopy WBC (+)=urinary sediment microscopy counts of 5-10/HP.The urinary sediment microscopy WBC (++)=Urinary Sediment Microscopic Counting 10-15/HP.The urinary sediment microscopy WBC (+++)=Urinary Sediment Microscopic Counting 15-20/HP.The urinary sediment microscopy WBC (++++)=Urinary Sediment Microscopic Counting>20/HP.

Table 2 - Comparison of clinical factors between patients with and without postoperative SIRS.
  SIRS  No SIRS  P  
Age (year)  51.61±12.80  52.11±11.85  0.684 
Sex (Male: Femal)  48: 60  523: 399  0.015 
BMI (Kg/m2 23.07±3.58  23.75±3.90  0.081 
Surgery time (min)  154.58±43.88  152.87±45.81  0.712 
Serun creatinine (μmol/L)  108.26±59.00  107.68±70.44  0.934 
Staghorn calculi (Yes: No)  52: 56  283: 639  <0.001 
Diabetes (Yes: No)  8: 100  56: 866  0.587 
Urine WBC       
Urine WBC (+): None  28: 46  84: 686  <0.001 
Urine WBC (++): None  20: 46  77: 686  <0.001 
Urine WBC (+++): None  10: 46  56: 686  0.009 
Urine WBC (++++): None  4: 46  19: 686  0.045 
Bacterial species detected in midstream urine       
Gram-negative bacteria: None  39: 65  104: 786  <0.001 
Gram-positive bacteria: None  3: 65  30: 786  0.759 
Fungus: None  1: 65  2: 786  0.144 

Table 3 - Multivartive analysis of factors between patients with and without postoperative SIRS.
  Odds ratio  P   Lower CI  Upper CI 
Sex  0.135  0.714  0.594  1.428 
Staghorn calculi  10.457  0.01  1.312  3.092 
Gram-negative bacteria  3.550  <0.001  2.205  5.715 
Urine WBC (+∼++++)  2.702  <0.001  1.604  4.551 

Légende :
CI: confidence interval.


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