With a nearly 3% rate of all urinary stones in general population, ureteral stones require a special attention in the majority of the cases due to the risk of obstruction and severe colic pain. Regarding this issue, while small, asymptomatic ureteral stones (< 5mm) may pass spontaneously in most cases, larger stones causing obstruction, pain and/or infection may require an active treatment. Ureteroscopy is the most commonly performed procedure in the minimal invasive removal of such stones.
Related with the ureteroscopic procedure, key to a successful operation is obtaining an easy ureteral access. Although this is possible in the majority of the cases in experienced hands, dimensions of the ureter may limit a successful access to the upper urinary tract in a certain percent of the cases. Regarding this critical issue, in a prospective study from a tertiary stone unit showed that, 9% of all ureteroscopies were aborted due to a failed ureteral access [12]. Ji et al. found a failed ureteral access rate of 11.5% in 512 ureteroscopic stone removal procedures [13]. Based on the likelihood of this problem, endourologists introduced several approaches for facilitating easier ureteral access to improve the efficacy and safety of ureteroscopy. Currently most surgeons tend to prefer ureteral stenting after the initial failed ureteroscopy to achieve passive ureteral dilatation and perform the definitive procedure after a few weeks. Although this method has shown to be effective with minimal complications [13], requirement of staged operation disturbing the patient and increasing the costs were the main disadvantages noted [14]. As a second approach, balloon dilatation of the ureter can be applied in the same session but serious complications such as ureteral injury / stricture may have been reported in some cases after this maneuver [15, 16]. Last but not least, use of alpha-blockers for ureteral relaxation (dilation) prior to ureteroscopic applications has been tried and Aydin et al. showed that alpha-blockers applied 3 days before ureteroscopy may increase success rates and decrease the complication rates [17]. However possible side effects of these medications seem to be the main concerns limiting the use in this purpose. As an alternative method, warmer irrigation fluid (40°C) has been used by Rezzai et al. in ureteroscopy, in an effort to create acute ureteral dilatation for easier ureteral access and they found out that warmer irrigation (40°C) creates an acceptable ureteral relaxation, decreases ureteral spasms compared to room temperature irrigation (22–24°C) thereby resulting in better surgical outcomes [10]. On the other hand, Patel et al. failed to show any difference regarding ureteral caliber and peristalsis between 37°C and 43°C irrigation ureteroscopy in a porcine model. Nevertheless, they stated that they continue using body temperature irrigation fluid in ureteroscopy [18]. In our study, we observed evident ureteral relaxation with significantly low spasms and peristalsis with warm fluid application compared to room temperature irrigation which provided easier access to the ureters and shortened the total procedural time in our cases.
Operation time is a highly crucial factor in ureteroscopy. Several reports stated that longer operation times may lead to certain complications during and after ureteroscopic procedures. In a retrospective analysis of 2,010 ureteroscopies, researchers found out that operation time was significantly higher in patients with complications compared to patients without complications [19]. Salciccia and colleagues showed that longer operation time is strongly associated with hospitalization need after ureteroscopy [20]. Additionally, longer operation times was found to be associated with higher grade complications (Clavien score ≥ III) such as ureteral perforation, infectious complications and urosepsis after ureteroscopy [21–23]. In this study, we found out that warm irrigation shortens operation time (21.55 ± 8.4) compared to room temperature irrigation (17.98 ± 9.9) (p < 0,05). Warmer irrigation facilitates ureteral access, decreases ureteral spasms therefore shorter operation times can be anticipated in ureteroscopy. Although there was no statistically significant difference in complication rates between two groups in our study (p:0,216), it is clear that warm irrigation is beneficial compared to room temperature irrigation to limit the risk of serious complications during these procedures.
Pain is amongst the most common complications of ureteroscopy. While increased pressure of the pelvicalyceal system due to continuous irrigation and the distention of renal capsule thought to be the primary cause, factors such as ureteral spasm, mucosal irritation can play role in pain after ureteroscopy [10]. In our study we found out that, warm irrigation significantly decreases post-operative pain after ureteroscopy compared to room temperature irrigation (p < 0.001). Lower IRP [10] and shorter operation times [21] are the main advantages of warm irrigation compared to room temperature irrigation in terms of decreased post-operative pain. Less hospital re-admission rates, less need for narcotics, shorter hospitalization and better QOL may be achieved by less painful ureteroscopies [24, 25]. Low IRP is also associated with lower post-operative infectious complications [26].
Based on the reported data in the literature and our findings as well, we may claim that as practical and low-cost approach, use of warm irrigation fluid during ureteroscopic stone removal procedures may provide certain advantages to the endourologists. An easy and atraumatic access to the ureteral lumen without having any difficulty is the main expectation of surgeons and based on the useful effects mentioned above irrigation with warm fluid during the procedure will certainly shorten the procedural time. This advantage will in turn result in limited complications (mainly in minor nature) and more importantly limited pain after the procedure which affects the patient’s quality of life to an important extent. Although not statistically significant the complication rate was also lower in cases being treated with warm irrigation fluid and this could also constitute another important advantage for the use of warm fluid for irrigation during ureteroscopic stone manipulations.
Our study has some limitations. First of all, our study consisted of relatively small patient group. However taking the highly limited data reported so far on this issue in the literature into account, we believe that our findings will be contributive enough on this aspect. Secondly our follow-up time was limited with 4 weeks and we have no data on the long-term effects and complications of this method. Lastly, although we showed that application of warm irrigation significantly decreases post-operative pain compared to room temperature irrigation in ureteroscopy, absence of the evaluation of quality-of-life assessment in our current study may constitute another limitation. We strongly believe that further studies with larger series of cases on the clinical use of this method may achieve more significant results.