Comparative effectiveness of high-power holmium laser lithotripsy for pediatric patients with kidney and ureteral stones

BACKGROUND

The comparative effectiveness of high-power laser technology for kidney stone surgery in pediatric patients is poorly understood. We compared outcomes for the 120 W Holmium:yttrium-aluminum-garnet (Ho:YAG) laser with MOSES technology to 30 W Ho:YAG laser for pediatric patients undergoing ureteroscopy with laser lithotripsy for kidney and ureteral stones.

OBJECTIVE

We evaluated the outcomes of the new MOSES laser technology as compared to low-power Ho:YAG lasers commonly used for kidney stone treatment in the pediatric population.

METHODS

We performed a retrospective cohort study of 131 consecutive patients aged 1-18 years who underwent ureteroscopy and laser lithotripsy for renal and ureteric calculi at a large freestanding children's hospital between 2013 and 2020. The primary outcome was the efficiency quotient, which incorporates stone clearance, auxiliary procedures, and retreatment rates. Outcomes were compared between groups using Chi-square or Fisher's exact tests and multivariable regression. A sensitivity analysis was performed extending the age limit to ≤21 years.

RESULTS

Outcomes are summarized in the table below. Median age of the cohort was 14 years with 53% of patients being female. MOSES laser had a higher efficiency quotient and was associated with a lower odds of post-operative emergency department visits (OR 0.2, 95% CI 0.0-1.0; p = 0.047). Operative time was similar. In the sensitivity analysis of patients ≤21 years, the statistical significance with fewer emergency department visits was lost and the efficiency quotient was lower.

DISCUSSION

Our results show that stone clearance is similar between the 120 W MOSES and 30 W Ho:YAG lasers. However, there are indications that high-power laser lithotripsy is more efficient due to fewer auxiliary procedures and a reduction in retreatment. In addition, higher power lasers were associated with fewer emergency department visits. The benefits appear to be greater among children ≤18 years. These exploratory findings are important for pediatric patients due to the requirement for general anesthesia for each procedure and their associated impact on children and their caregivers.

CONCLUSIONS

High-power laser lithotripsy may be more efficient than lower power laser lithotripsy, which is driven by the fewer auxiliary procedures and reduction in retreatment particularly among youth ≤18 years old.

A new hydrophilic biodegradable ureteral stent restrain encrustation both in vitro and in vivo

Ureteral stents have been widely used as biomedical devices to treat some urological diseases for several decades. However, the encrustation complications hamper the long-time clinical use of the ureteral stents. In this work, a new type of biodegradable material for the ureteral stents, methoxypoly(ethylene glycol)-block-poly(L-lactide-ran-Ɛ-caprolactone) (mPEG-PLACL), is evaluated to overcome this problem. The results show that the hydrophilicity and degradation rate in artificial urine of mPEG-PLACL are both significantly increased. It is worth noting that the mPEG-PLACL shows a lower amount of encrustation after immersing the stents in the dynamic urinary extracorporeal circulation (DUEC) model for 7 days. In addition, 71% Ca and 92% Mg are inhibited in vivo by quantitative analysis. Pathological analysis exhibit that the mPEG-PLACL cause less diffuse mucosal hyperplasia after 7 weeks of implantation. All the results indicate that this new type of biodegradable material had an excellent potential for the ureteral stents in the future.

Latest advancements in ureteral stent technology

Urological diseases such as tumours, kidney stones, or strictures in the ureter can lead to a number of health consequences, including life-threatening complications. Ureteral stents have been widely used as a valid solution to restore compromised urological function. Despite their clinical success, stents are subject to failure due to encrustation and biofilm formation, potentially leading to urinary tract infection. The current review focuses on recent advancements in ureteral stent technology, which have been reported in recent scientific journals or patents. Web of Science and Google Scholar have been used as a search engine to perform this review, using the keywords "Ureteral + Stent + Design", "Ureteral + Stent + Material + Coating", "Ureteric + Stent" and "Ureteral + Stent". A significant proportion of technological developments has focused on innovating the stent design to overcome migration and urinary reflux, as well as investigating novel materials and coatings to prevent biofilm formation, such as poly(N,N-dimethylacrylamide) (PDMMA) and swellable polyethylene glycol diacrylate (PEGDA). Biodegradable ureteral stents (BUS) have also emerged as a new generation of endourological devices, overcoming the "forgotten stent syndrome" and reducing healthcare costs. Moreover, efforts have been made to develop pre-clinical test methods, both experimental and computational, which could be employed as a screening platform to inform the design of novel stent technologies.

Predictors of spontaneous ureteral stone passage in the presence of an indwelling ureteral stent

Patients presenting acutely with obstructing stones often have a ureteral stent placed as a temporizing solution. Ureteroscopy is then commonly performed in a staged fashion, but occasionally the stone is found to have passed. We aimed to identify the frequency and predictors of ureteral stone passage with a stent in place. Records were reviewed to identify patients who had a stent placed for a single ureteral stone. Subsequent ureteroscopy or CT scan was used to ascertain stone passage. Effect of age, gender, BMI, stone diameter, alpha blocker use, urinary tract infection, hydronephrosis, and stent duration on stone passage was assessed. Inclusion and exclusion criteria were met in 209 patients. Mean maximum stone diameter was 6.5 ± 2.5 mm. Passage rates for stones < 3 mm, 3-4.9 mm, 5-6.9 mm, and ≥ 7 mm were 50%, 13%, 10%, and 0%, respectively. The overall rate of passage was 8%. Stone passage was associated with smaller maximum stone diameter, more distal stone location, and longer duration of stent before ureteroscopy/CT on univariate analysis (p < 0.01). Stone diameter and stent duration remained significantly associated on multivariable analysis (p = 0.001 and p = 0.05, respectively). Our findings suggest ureteral stone passage with a concurrent ureteral stent is not a rare event as it occurred in 14% of stones less then 7 mm in maximum diameter. Stone size and duration of stent before ureteroscopy or CT were found to be independent predictors of passage. Select patients with small ureteral stones who have been stented should be considered for a trial of urine straining or repeat imaging before subsequent ureteroscopy.

Investigation of a novel gradient degradable ureteral stent in a beagle dog model

Ureteral stents are widely used in the department of urology, while the stent could result in many stent-associated complications, such as encrustation, a forgotten stent and patient discomfort. Thus, we developed a novel gradient degradable ureteral stent, which could degrade gradient in vivo, and assessed its effectiveness of the drainage, degradation and biocompatibility in a beagle dog model. In the present study, the degradation time and cytotoxicity were investigated in vitro. And the beagle dogs were inserted with a degradable stent or a biostable stent, and blood studies, liver function tests, renal function tests, urine studies, X-ray, excretory urograms and computerized tomography were performed at immediately, two weeks, four weeks and six weeks postoperative. The results showed that the drainage of the novel stent is similar to the conventional stent, while the biocompatibility and antibacterial ability of the novel stents are better than the conventional stents. The stents we developed provide an alternative for urologists and more assays would be performed in detail to assess the property of the stents.

Ureteral stents increase risk of postoperative acute kidney injury following colorectal surgery

BACKGROUND

Ureteral stents are commonly placed before colorectal resection to assist in identification of ureters and prevent injury. Acute kidney injury (AKI) is a common cause of morbidity and increased cost following colorectal surgery. Although previously associated with reflex anuria, prophylactic stents have not been found to increase AKI. We sought to determine the impact of ureteral stents on the incidence of AKI following colorectal surgery.

METHODS

All patients undergoing colon or rectal resection at a single institution between 2005 and 2015 were reviewed using American College of Surgeons National Surgical Quality Improvement Program dataset. AKI was defined as a rise in serum creatinine to ≥ 1.5 times the preoperative value. Univariate and multivariate regression analyses were performed to identify independent predictors of AKI.

RESULTS

2910 patients underwent colorectal resection. Prophylactic ureteral stents were placed in 129 patients (4.6%). Postoperative AKI occurred in 335 (11.5%) patients during their hospitalization. The stent group demonstrated increased AKI incidence (32.6% vs. 10.5%; p < 0.0001) with bilateral having a higher rate than unilateral stents. Hospital costs were higher in the stent group ($23,629 vs. $16,091; p < 0.0001), and patients with bilateral stents had the highest costs. Multivariable logistic regression identified predictors of AKI after colorectal surgery including age, procedure duration, and ureteral stent placement.

CONCLUSIONS

Prophylactic ureteral stents independently increased AKI risk when placed prior to colorectal surgery. These data demonstrate increased morbidity and hospital costs related to usage of stents in colorectal surgery, indicating that placement should be limited to patients with highest potential benefit.

A prospective and randomized comparison of rigid ureteroscopic to flexible cystoscopic retrieval of ureteral stents

Background

Flexible cystoscopy has become an accepted alternative for stent retrieval. However, it is associated with higher cost. Some reports have described experiences of using rigid ureteroscope to retrieve ureteral stents. We compared rigid ureteroscopic to flexible cystoscopic retrieval of ureteral stents in a prospective and randomized clinical trial.

Methods

Three hundred patients treated with ureteral stents between July 2012 and July 2013 were accrued in this study. These patients were divided into two groups using the random number table method. Group A, with 162 patients, had stents removed with a flexible cystoscope and Group B, with 138 patients, had stents removed with a rigid ureteroscope. All procedures were performed under topical anesthesia by the same urologist. Patients in each group were compared in terms of preoperative, perioperative, and postoperative data. Postoperative data were collected using telephone interview on the postoperative day two. The postoperative questionnaire used included three items: hematuria, irritable bladder symptoms, and pain scores.

Results

All the stents were retrieved successfully. No statistical differences were noted between the two groups in terms of gender, age, laterality and duration of the stents, operative time, postoperative hematuria, irritable bladder symptoms, and pain scores. The per-use cost of instrument was much higher for the flexible cystoscopic group, RMB 723.1 versus 214.3 (USD 107.9 versus 28.2), P < 0.05.

Conclusion

Ureteral stent retrieval using rigid ureteroscope under topical anesthesia is as safe and effective as flexible cystoscope but with a much lower cost to patients.

Trial registration

This study was registered with Chinese Clinical Trial Registry on March 27, 2017 (retrospective registration) with a trial registration number of ChiCTR-IOR-17010986.

[Management of ureteral obstruction : Value of percutaneous nephrostomy and ureteral stents]

Ureteral obstruction represents a heterogeneous disease pattern and is treated by ureteral stenting or percutaneous nephrostomy (PCN) depending on the necessity. The benefits of urinary diversion with ureteral stenting or PCN in malignant ureteral obstruction (MUO) for patient survival are only moderate. No differences have been found between ureteral stenting and PCN in MUO with regard to median patient survival and complication rates. In cases of MUO there is currently no evidence that urinary diversion improves the quality of life. Alternative concepts of ureteral stenting, such as tandem ureteral stents, metallic ureteral stents or metal mesh ureteral stents have not yet shown clear benefits. In benign ureteral obstruction, prospective randomized studies have demonstrated comparable quality of life after PCN or ureteral stenting. The method of choice for urinary diversion is influenced by the recommendations, personal experience of the clinician and the availability of the method.

Drug-eluting biodegradable ureteral stent: New approach for urothelial tumors of upper urinary tract cancer

Upper urinary tract urothelial carcinoma (UTUC) accounts for 5-10% of urothelial carcinomas and is a disease that has not been widely studied as carcinoma of the bladder. To avoid the problems of conventional therapies, such as the need for frequent drug instillation due to poor drug retention, we developed a biodegradable ureteral stent (BUS) impregnated by supercritical fluid CO₂ (scCO₂) with the most commonly used anti-cancer drugs, namely paclitaxel, epirubicin, doxorubicin, and gemcitabine. The release kinetics of anti-cancer therapeutics from drug-eluting stents was measured in artificial urine solution (AUS). The in vitro release showed a faster release in the first 72h for the four anti-cancer drugs, after this time a plateau was achieved and finally the stent degraded after 9days. Regarding the amount of impregnated drugs by scCO₂, gemcitabine showed the highest amount of loading (19.57μg _drug/mg _polymer: 2% loaded), while the lowest amount was obtained for paclitaxel (0.067μg _drug/mg _polymer: 0.01% loaded). A cancer cell line (T24) was exposed to graded concentrations (0.01-2000ng/ml) of each drugs for 4 and 72h to determine the sensitivities of the cells to each drug (IC₅₀). The direct and indirect contact study of the anti-cancer biodegradable ureteral stents with the T24 and HUVEC cell lines confirmed the anti-tumoral effect of the BUS impregnated with the four anti-cancer drugs tested, reducing around 75% of the viability of the T24 cell line after 72h and demonstrating minimal cytotoxic effect on HUVECs.

Preparation, degradation and in vitro release of ciprofloxacin-eluting ureteral stents for potential antibacterial application

Drug-eluting stents with biodegradable polymers as reservoirs have shown great potential in the application of interventional therapy due to their capability of local drug delivery. Herein, poly(l-lactide-co-ε-caprolactone) (PLCL) with three different compositions as carriers for ciprofloxacin lactate (CIP) was coated on ureteral stents by the dipping method. To simulate a body environment, degradation behavior of PLCL as both the bulk film and the stent coating was evaluated in artificial urine (AU, pH6.20) respectively at 37°C for 120days by tracing their weight/Mn loss, water absorption and surface morphologies. Furthermore, the release profile of the eluting drug CIP on each stent exhibited a three-stage pattern, which was greatly affected by the degradation behavior of PLCL except for the burst stage. Interestingly, the degradation results on both macroscopic and molecular level indicated that the release mechanism at stage I was mainly controlled by chain scission instead of the weight loss or morphological changes of the coatings. While for stage II, the release profile was dominated by erosion resulting from the hydrolysis reaction autocatalyzed by acidic degradation residues. In addition, ciprofloxacin-loaded coatings displayed a significant bacterial resistance against E. coli and S. aureus without obvious cytotoxicity to Human foreskin fibroblasts (HFFs). Our results suggested that PLCL copolymers with tunable degradation rate as carriers for ciprofloxacin lactate could be used as a promising long-term antibacterial coating for ureteral stents.

Use of percutaneous nephrostomy and ureteral stenting in management of ureteral obstruction

The management options for ureteral obstruction are diverse, including retrograde ureteral stent insertion or antegrade nephrostomy placement, with or without eventual antegrade stent insertion. There is currently no consensus on the ideal treatment or treatment pathway for ureteral obstruction owing, in part, to the varied etiologies of obstruction and diversity of institutional practices. Additionally, different clinicians such as internists, urologists, oncologists and radiologists are often involved in the care of patients with ureteral obstruction and may have differing opinions concerning the best management strategy. The purpose of this manuscript was to review available literature that compares percutaneous nephrostomy placement vs ureteral stenting in the management of ureteral obstruction from both benign and malignant etiologies.

Morbidity and impact on quality of life in patients with indwelling ureteral stents: A 10-year clinical experience

Objective:

Prospective analysis of the prevalence of symptoms, tolerability and complications associated with ureteral stents and their impact on quality of life based on the Flanagan Quality of Life Scale and a not-validated questionnaire from our clinic.

Methods:

A total of 2200 adult patient participated to this study in a period of 10 years (2003-2012). Those patients were asked to complete the QOLS and a not-validated questionnaire from our clinic, before ureteral indwelling, 7 day after ureteral indwelling and 14 days after removal of the stent.

Results:

Total 1520 patient aged between 18 and 84 years completed the study. The analysis of data showed that the unpleasant symptoms caused by stent were encountered more frequently at 7 days after stent insertion, in terms of urinary frequency, dysuria, urgency and macroscopic haematuria, this difference being statistically significant (p<0.05). After analysis the responses to QOLS questionnaire, at 7 days after stent placement, mean scores show a clear reduction in the QoL of those patients, in all cases the standard deviation being at a great value, indicating a high variability of responses, but at 14 days after its suppression of stent the average scores are somewhat closer to the baseline.

Conclusions:

Our study brings many elements that shows a statistically significant increase in the incidence of numerous side effects and impaired quality of life. It contributes to existing data from the literature as regards the knowledge of the pathology determined by the presence of foreign body in the urinary tract and in providing patient counseling.

The role of ureteral stents for all ureteroneocystostomies in kidney transplants

BACKGROUND

Despite significant advancements in renal transplantation, certain basic surgical practices such as the routine use of ureteral stents (US) remain controversial. A recent met-analysis of ureteral stenting concluded that the routine use of US resulted in improved outcomes. In contrast, the indiscriminate use of US can lead to adverse complications.

OBJECTIVE

To better define this question, we reviewed our single center experience in which US were placed selectively.

METHODS

301 patients were eligible to be enrolled. 55 living donor and 246 deceased-donor charts were analyzed for donor and recipient clinical characteristics, immunosuppressive therapy and outcomes.

RESULTS

28 US were placed for either small bladder capacity (n=7), unhealthy appearing bladder tissue (n=8) or for an uncertain vascular supply to the ureter (n=13). Patients with US did not develop urinary leaks, 8 (28%) developed complications including obstruction, encrustation, and urinary tract infections. 12 (4.3%) non-stented patients developed a clinically significant urinary leak. Risk factors for urinary leaks included dual and en-bloc pediatric donor kidney transplants, extended criteria donors and the use of single U stitch technique for ureteral anastomoses.

CONCLUSION

Our results demonstrate that the majority of patients can be successfully transplanted without the routine use of US. Selective use of US should be reserved for high-risk situations.