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Dear colleagues, once again a newsletter of our ureteral stents series. On this occasion, three very recent manuscripts update us on aspects related to ureteral stents. 

The selection includes a first study that provides us with future information on strategies to be taken into account to solve the important problems of the increasingly frequent emergence of antibiotic resistance in the urinary environment. 

On the other hand, an interesting clinical study that tries to shed light on an issue that does not present clear scientific evidence in the urological literature, related to ureteral stent insertion in patients undergoing tubeless complete supine PCNL.

Finally, a study that retrospectively delves into the management of patients with ureteral obstruction at the time of the global pandemic of COVID-19 and ureteral stenting. I hope you enjoy this information and its future applications in patients.

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Despite the widespread use of ureteral stents in the management of urinary stones and obstructive pathologies. The stents are prone to colonization by urogenital flora, leading to biofilm formation and of course asymptomatic bacteriuria. Mainly, E. coli and K. pneumoniae. Although asymptomatic bacteriuria per se is not harmful, it can potentially develop into serious infections such as urosepsis during ‘mucosal injury-inducing endourological procedures. We must remember that bacteria from ureteral stents or in suspension may spread systematically due to increased intraluminal pressure during ureteroscopy, potentially leading to symptomatic UTI.

The Infectious Disease Society of America recommends a urine culture prior to manipulation to guide antibiotic prophylaxis, with third-generation cephalosporins or carbapenems being frequent. Unfortunately, biofilm associated with ureteral stents exhibit antibiotic tolerance and thus survive otherwise lethal doses of antibiotics, because of the project effect that the biofilm facilitates for the bacteria.

Quinolones have an excellent anti-biofilm activity, but resistance in E. coli or K. pneumoniae approaches 20%, related to a single mutation in the gyrase. The aim of this trial is to explore new strategies for rise in antibiotic resistance and the potentiation of existing antibiotics to circumventing bottle necks of antibiotics developments. Authors assessed the combination of aminoglycosides with mannitol. This combination with mannitol allows it to use its advantages such as the oto- and nephroprotective effect. Therefore, the low dosage reduced potential side effects and toxicity of aminoglycosides and on the other hand, mannitol seems to provide additional direct protection. 

The combination of mannitol and low-dose amikamicin holds potential as a future standard in antimicrobial prophylaxis for endourological interventions. 
It is clear that we need to make progress in the management of the development of asymptomatic bacteriuria directly related to the development of biofilm and the increase in resistance that is being demonstrated with current antimicrobials. New strategies should be assessed such as prophylaxis, new coatings and biomaterials that reduce bacterial adhesion to stents.

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This recent study evaluates an important issue in decision making related to ureteral stent insertion in patients undergoing tubeless complete supine PCNL. There are several studies conducted on tubeless supine PCNL and it has been shown that stone evacuation is better and easier in the supine position compared to prone, and there will be fewer residual stones, which causes less trouble for patients and decreased renal pelvis pressures. But on the other hand, there is no scientific literature that compares outcomes of tubeless and totally tubeless PCNL in complete supine position. Therefore, in this study authors aimed to compare the outcomes of tubeless complete supine PCNL with insertion of ureteral stent and totally tubeless PCNL with perioperative ureteral stent.

123 patients, over 18 years old, with staghorn stones who underwent PCNL were assessed. Patients with absolute indications for a clinical ureteral stent, single kidney, and ureteral perforation were excluded.

The items related to: fever, hematuria, transfusion, Stone free rate, readmission, return to normal life, duration of hospitalization and laboratory results (creatinine, hemoglobin, etc.) were assessed. The decision to insert or not to insert a double J stent was made based on the surgeon’s preference according to the patient’s condition, perioperative complications and the presence of suspected residual stones. In the group in which a ureteral stent is placed, it is removed two to four weeks after endourology approach.

Regarding the results of this clinical study, the mean operative time was longer in ureteral stent group. Although there was no statistically significant difference between two groups regarding the stone free rate, the success rate of the operation was notably higher in ureteral stent group than the perioperative stent (90.5% vs. 79.8%). The incidence of major complications was higher in the perioperative stent group with no significant difference. Consequently, the postoperative hospitalization period in the perioperative stent group was significantly longer. The main reason for this difference according to the study authors can be the complaint of patients in the perioperative stent group of renal colic, which is caused by residual stones.

The authors conclude that, although the need for ureteral stent in PCNL for staghorn stone is challenging, inserting double-J stent is recommended in this group of patients because of shorter hospital stay, shorter time to return to normal life and better success rate.

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This last selected manuscript, a retrospective analysis, discusses the postoperative safety of patients undergoing cystoscopy with ureteral stenting for obstructing ureteral stones who tested positive for COVID-19, during the pandemic.

The authors selected 1,408 patients who underwent cystoscopy and ureteral stent placement (between June 5, 2020 and December 31, 2022) after presenting to the emergency department. Patients were stratified by whether they had a positive COVID-19 test on admission. During those days, changes in practice patterns for nephrolithiasis were noted as the rate of non-operative management increased, the rate of shockwave lithotripsy and nephrostomy tube placement without general anesthesia increased, and the delay between renal decompression and definitive stone surgery increase.

Researchers assessed the safety of cystoscopy and ureteral stenting by assessing the rate and predictors of post-operative ICU admission and 30-day mortality. Additional post-operative outcomes of the patients were assessed in the form of length of stay, 30- and 90-day readmission rates and 90-day mortality.

Among the 1,408 patients included in the study with ureteral stent insertion, 3.91% of patients tested positive for COVID-19. Univariate and multivariate logistic regression was performed to identify predictors of 30-day mortality following cystoscopy, ureteral stent placement. On univariate analysis, predictors of 30-day mortality include testing positive for COVID-19, older age, longer operative duration, sedation for anesthesia, ureteral stent placement occurring in the setting of infection and a medical history inclusive of heart disease, hypertension. On multivariate analysis, a positive COVID-19 viral test was a predictor of 30-day mortality. Other variables that were statistically significant on the multivariate model include older age, a past medical history of heart disease and obesity, longer procedure time, anesthesia in the form of intravenous sedation, and ureteral stent placement in the setting of a urinary tract infection. A positive COVID-19 viral test was the strongest predictor in terms of odds of 30-day mortality.

The study demonstrates that patients who underwent non-elective cystoscopy with ureteral stenting while also being diagnosed with COVID-19 had a seven-fold increase in risk of 30-day mortality. Thirty- and ninety-day all-cause mortality for patients within this retrospective study was noted to be 1.5% and 2.1% respectively, as compared to 7.3% and 9.1% respectively for patients that tested positive for COVID-19 infection who underwent endourology approach.