Percutaneous nephrolithotomy (PCNL) was the treatment of choice for large renal calculi however, it was not free of complications. Urosepsis was a potentially catastrophic complication which could progress to multiorgan dysfunction syndrome (MODS). The risk of post-PCNL(Percutaneous Nephrolithotomy) urosepsis is 0.3-4.7% and has a mortality of 25-60%[4–5]. Delay in diagnosis and treatment of sepsis increased mortality, prolonged length of hospital stay, and increased the costs [6–7].
Incidence of urosepsis had increased with the increasing number of PCNL(Percutaneous nephrolithotomy) performed every year. Attempts had been made to identify factors contributing to the development of SIRS ( Systemic Inflammatory Response Syndrome ). However, no single method or scoring system had been designed to predict the probability of urosepsis[8]. Risk assessment tools had been widely used in disease diagnosis and prognosis[9]. Early diagnosis and treatment of urosepsis was difficult due to lack of a predictive scoring system. The development of evaluation system based on different risk levels that could help in early recognition of urosepsis, decrease its rate of complication and improve prognosis was today’s need. This study aims to evaluate the risk factors associated to urosepsis after percutaneous nephrolithotomy (PCNL) and establish a risk assessment tools that could help in early diagnosis of high-risk patients and prevent septic complications.
Tian et al[10] included 164 post PCNL(Percutaneous Nephrolithotomy) patients to study infectious complications after percutaneous nephrolithotomy (PCNL) and established a prediction tool for postoperative complications. They proposed that patients with larger stone size and preoperative urinary tract infection were high risk patient of developing SIRS (Systemic Inflammatory Response Syndrome ) and fever after the procedure. In a retrospective study[11] over a period of 3 years Sumit Suresh Bansal and colleges concluded that stone size >25 mm, prolonged operative time >120 min, and significant bleeding requiring transfusion were significantly correlated with postoperative severe sepsis. In anorther prospective study[11] to determine the predictors of infectious complications following PCNL(Percutaneous Nephrolithotomy), 332 patients with renal or upper ureteric calculi were divided into 2 groups depending on incidence of infectious complications. In patients with renal failure, diabetes mellitus, preoperative PCN (Percukaneous Nephrostomy) placement, staghorn calculi, severe HDN(Hemolytic Disease of the Newborn), multiple punctures, and prolonged duration of surgery. Post-PCNL(Percutaneous Nephrolithotomy)infectious complications were more commonly observed.
All these studies had some limitation mainly the small number of sample size, single center study and limited number of variables considered for evaluations. Retrospective study from single institute, which might lead to selection bias and cause-effect relationship between different biochemical parameters and co-morbid conditions were left out. Thus we attempted to establish a scoring system based on the meta-analysis which including 12 factors and RCT (Randomized Controlled Trial) studies which was more accurate and comprehensive to establish a clinically useful evaluation system.
We carried a meta-analysis on risk factors of urosepsis following PCNL(Percutaneous Nephrolithotomy) and based on its results formulated the PuRass(Risk Assessment Scoring System) scale. In PuRass scale evaluation, post-PCNL(Percutaneous Nephrolithotomy) urosepsis group yielded higher score than in non urolological cause of urosepsis, indicating post-PCNL(Percutaneous Nephrolithotomy) urosepsis group prone to infection. The ROC(Receiver Operating Characteristic) cure with AUC (Area Under ROC Curve) 0.913 could effectively predict the probability of post-operative infection. At a cutoff value of 8.5 the specificity and sensitivity were 89.4% and 90.0% suggesting patients above the cutoff values having higher chance of acquiring post-operative infection. These were very important clinical information that could help urologist to prepare and take more precaution in these group of patients.
We performed risk assessment in 293 patients using the PuRass scale, majority of the post PCNL(Percutaneous Nephrolithotomy) patients were at moderate risk of urosepsis that was consistence to clinical practice and many published literatures.
But in majority of non-urological cause of urosepsis patients the score was low and there was a rapid decline in number of such patients with rise in the score. This helped surgeons to be more careful specially for high risk patients and avoiding associated complications.
Limitation of the study
The retrospective nature of the analysis from a region and a single institution might cause possible bias in the scoring system. Further verification from different regions or in multi center studies was needed before the widespread use of this evaluation score. Urosepsis following PCNL(Percutaneous Nephrolithotomy) depended on variety of the preoperative and perioperative factors. Earlier reports had identified number and size of tracts, bleeding, surgical time, irritants used, pelvic pressure, nephrostomy care as major factors associated with urosepsis[12–16]. But the surgeons experience and its association with incidence of urosepsis was not clear. Since preoperative factors played an important role in the incidence of urosepsis, the peri and postoperative factors were not included in the meta- analysis used to established this scoring system. Thus, this evaluation system might not be enough to precisely assess the risk of postoperative urinary sepsis.
We had developed a risk assessment system to assess the probability of urosepsis following PCNL(Percutaneous Nephrolithotomy). The clinical application and effectiveness were also validated. The risk assessment system was useful in quantification of the operative risk before surgery could help surgeons timely and accurate appraise the risk of postoperative urosepsis. It also enabled to screen high risk patients and strictly monitor these patients. Thus, this scoring system could identify the risk factors and guide to use appropriate measures to improve the prognosis of PCNL(Percutaneous Nephrolithotomy).