Discussion
SULL is an effective surgical method with high stone-free rate for treating ureteral stones, yet infectious complications are inevitable (6,7). Infectious complications following URS may lead to an extended period of hospital stay with an impact on the prognosis of patients, increasing the potential risk for multiple organ dysfunction (7–9). As a result, it is important to prevent infection-related complications in order to minimize morbidity rates. In this review, the incidence of SIRS was 1.7 % which is consistent with the rates stated in previous studies (10–12).
There are several modifiable and non-modifiable factors mentioned in the literature that may be used as predictors of SIRS. Higher SIRS rates were correlated with larger stone burden, surgical time, infectious stone, irrigation with an increased flow rate, small-caliber UAS, URS preceding after obstructive pyelonephritis, a positive PBUC, and female sex (7,8,13). Furthermore, history of previous urologic stone surgery, history of recurrent UTIs, preoperative pyuria, preoperative acute pyelonephritis, hydronephrosis, and the placement of a urethral catheter, DJS or percutaneous nephrostomy were recognized as factors increasing the risk for infectious complications in URS (14–17). In both univariable and multivariable analysis conducted in our study; stone burden, surgical time, and the history of recurrent UTI were statistically significant predictors for SIRS.
Our research was not able to demonstrate the impact of factors in certain cases such as URS preceding obstructive pyelonephritis, acute pyelonephritis, and hydronephrosis due to the fact that all patients had stone surgery as elective cases. Compared with the non-SIRS group, the female sex rate in the SIRS group was higher, yet the difference was not statistically significant. The presence of DJS preoperatively was not identified as a predictive factor for SIRS in our study. We thought that the reason for this result might be that patients who were placed DJ stents due to obstructive uropathy were not included in the study. The only reason for having a DJS preoperatively was passive dilatation in our study. Additionally, this outcome may have occurred as the mean time period for DJS insertion to achieve passive dilatation was less than 21 days (18).
Stone cultures for prediction of infectious complications following PNL surgery and the management of postoperative antibiotic treatment were found to have an increased value in recent years (19–21). The current research revealed samples of preoperative bladder urine to be insufficient in identifying microorganisms surrounding the stone because the fragmented stone cultures were usually different from the stone surface or PBUC (22).
In contrary to previous studies, no association was shown between renal pelvic urine culture (RPUC), stone culture (SC) and sepsis or SIRS in the study by Koras et al.(23). The common message of all the studies, however, is that intraoperative cultures may be crucial for guidance on antibiotic treatment postoperatively. In a study exploring the association of RPUC and SC with SIRS following URS, it was stated that PBUC was incompatible with RPUC and SC (9). Reconsideration of the antibiotic therapy according to the results of the RPUC and SC was recommended in cases of postoperative infectious complications (9). Nevertheless, in the current study, 20 out of 23 patients with SIRS had PBUC, RPUC or SC growth, and PBUC, RPUC and SC were observed to be compatible in eight (40 %) patients. Furthermore, no growth was observed in RPUC and SC in five (25%) patients, and only PBUC positivity was found; postoperative antibiotic treatment was adjusted according to the PBUC results. Since RPUC and SC may be considered as time-consuming tests, it is clear that the value of PBUC may never be underestimated. As we primarily aimed to assess the impact of the time between PBUC and RIRS on SIRS, evaluating the effect of the duration between PBUC and SULL more precisely, the positivity of PBUC was incorporated as a variable for predicting SIRS in the study.
In countries with a high prevalence of urinary system stone disease in tertiary referral institutions such as our clinic, waiting times are extended in elective stone surgeries such as SULL. This leads to an increase in the duration between PBUC and SULL. The lengthening of this time interval raises questions in the minds of both patients and doctors. Surgeons may become suspicious that as time increases, re-infections may occur in those patients with a risk of UTI. It was shown in our research that the time period between PBUC and SULL was not a predictive factor for SIRS. Extending the waiting time for SULL may increase the risk of complications caused by infection. The outcome revealed in our study may be a result of the fact that factors such as stone burden, surgical time and history of recurrent UTI, identified in the literature as risk factors for infectious complications postoperatively (8,14,24), were observed more frequently in SIRS patients in comparison to patients with a normal postoperative period. The possible impact of the lengthening the waiting time in the study may have been obscured by these variables.
There are some limitations to our study. The operations were undertaken by urology specialists and residents. Thus, the parameters depending on the operator may be biased. The retrospective design was another limitation of our study. In addition, this study only reveals the experience of a single center.