The safety of ureteral stenting with the use of potassium citrate for management of renal uric acid stones

Terahertz Metamaterial Sensor for Sensitive Detection of Citrate Salt Solutions

Citrate salts (CSs), as one type of organic salts, have been widely used in the food and pharmaceutical industries. Accurate and quantitative detection of CSs in food and medicine is very important for health and safety. In this study, an asymmetric double-opening ring metamaterial sensor is designed, fabricated, and used to detect citrate salts combined with THz spectroscopy. Factors that influence the sensitivity of the metamaterial sensor including the opening positions and the arrangement of the metal opening ring unit, the refraction index and the thickness of the analyte deposited on the metamaterial sensor were analyzed and discussed from electromagnetic simulations and THz spectroscopy measurements. Based on the high sensitivity of the metamaterial sensor to the refractive index of the analyte, six different citrate salt solutions with low concentrations were well identified. Therefore, THz spectroscopy combined with a metamaterials sensor can provide a new, rapid, and accurate detection of citrate salts.

The impact of stenting prior to oral chemolysis of upper urinary tract uric acid stones

PURPOSE

To evaluate the impact of ureteral stenting on the success rate of oral chemolysis in the management of suspected uric acid upper urinary tract (UUT) stones.

METHODS

Retrospective matched-pair analysis of 172 patients treated with oral chemolysis from 01/2010 to 12/2019. Patients with low density (upon non-contrast enhanced computer tomography [NCCT]), radiolucent (on plain radiography) urinary stones, a low urine pH (< 6) and/or history of uric acid urolithiasis were included. Potassium citrate and/or sodium bicarbonate were used for alkalization (target urine pH: 6.5-7.2). Patient 1:1 matching was performed for the presence of indwelling ureteral stent, stone diameter, stone density, and stone localization. Stone-free status was evaluated after 12 weeks using NCCT. Multivariable logistic regression analysis was used to assess factors affecting the outcome.

RESULTS

Mean patient age was 61 years (73% males). Mean stone size was 12 mm. Overall success rates after 12-weeks of chemolysis for stones at any localization in the UUT and ureteral stones were 60.5 and 77.3%, respectively. Smaller stone size (OR = 0.94; CI 0.888-0.992; p = 0.026) and lower pre-treatment urine pH (OR = 0.131; CI 0.023-0.737; p = 0.021) significantly increased the success of oral chemolysis. Ureteral stenting did not have any impact on the efficacy of oral chemolysis.

CONCLUSION

Oral chemolysis is an effective treatment modality for patients with UUT stones suspected of uric acid content irrespective of ureteral stenting. Smaller stone diameter and lower urine pH at diagnosis increase its efficacy.

Problems and solutions of stent biofilm and encrustations: A review of literature

A ureteral stent is a commonly implanted urological device in patients with urinary tract obstruction. The main role of these stents is to allow adequate drainage of urine from the kidney into the bladder. Individuals with strictures, tumors, or obstructions from urinary stones do not have adequate urine flow and require ureteral stents as a part of their treatment to avoid potential hydronephrosis and renal failure. Although ureteral stents are highly effective in treating urinary tract obstructions, they have associated morbidities, such as biofilm formation and encrustation. Researchers have studied about how to diminish these negative outcomes by developing novel stent materials. Different coatings and biomaterials have been developed to reduce bacterial adhesion and crystal deposition onto the stent surfaces. Moreover, new investigation technologies, such as microfluidic platforms and encrustation sensors, have been utilized to better study the stents. Biofilms and encrustations can stem from bacterial origins; therefore, understanding the urinary microbiome will also provide insight into the solutions for treating them. There are still some gaps in our knowledge regarding the exact underlying mechanisms of stent-associated biofilms and encrustation. Future studies should include continuous testing of novel stent biomaterials for safety and efficacy, developing new technologies for identifying and extracting biofilms, enriching the assessment of stent encrustation, and diving deeper into understanding the urinary microbiome.