The Application of Next-Generation Sequencing in Preoperative Evaluation for Urologic Stone Surgery.

Introduction: Next-generation sequencing (NGS) is a new molecular technique for identifying microorganisms. Treating bacteriuria in patients undergoing stone removal procedures is important for preventing postoperative urinary tract infection (UTI). The objective of this study is to assess the usefulness of preoperative urine NGS testing by comparing NGS with standard urine culture in predicting postoperative UTI after ureteroscopic lithotripsy (URSL) and percutaneous nephrolithotomy (PCNL). Materials and Methods: This prospective study was conducted from February 16, 2022, to January 11, 2024. Sixty subjects who underwent URSL or PCNL were included. Preoperative voided urine samples were collected for urine culture and tested by MicroGenDX for urine polymerase chain reaction (PCR) and urine NGS. Stone specimens obtained intraoperatively were also sent for stone culture and MicrogenDx. Patients were monitored for 4 weeks post-operation for recording clinical outcomes related to infections and complications. Results: Twenty-six (43.3%) male and 34 (56.7%) female participants were included. Twenty-six (43.3%) patients underwent PCNL (15 standard PCNL and 11 mini PCNL), and 34 (56.7%) underwent URSL. Standard urine culture identified positive results in 26 cases (43.3%), PCR for 17 cases (28.3%), and NGS for 31 cases (51.7%). The overall postoperative UTI rate was 6 (10%). Standard urine culture demonstrated a sensitivity of 50%, specificity of 57.4%, and accuracy of 56.7%. Positive predictive value (PPV) was notably poor at 11.5%. Urine NGS showed a higher sensitivity of 83.3%, specificity of 53.7%, accuracy of 55%, and PPV of 16.7%. Conclusion: Urine NGS significantly improves the sensitivity of detecting microorganisms in preoperative urine compared with standard urine culture. Despite its high sensitivity and capability to identify nonculturable bacteria, using NGS alongside standard urine culture is recommended. This parallel approach harnesses the strengths of both methods. Integrating NGS into standard practice could elevate the quality of care, especially for patients at high risk of UTIs, such as those undergoing invasive stone removal procedures.

In vitro Comparison of the Mechanical and Optical Characteristics of 5 Disposable Flexible Ureteroscopes.

INTRODUCTION: Disposable (single-use) flexible ureteroscopes are alternatives to reusable ureteroscopes. With their superior surgical efficacy and safety in the presence of upper urinary calculi, disposable ureteroscopes aim to overcome the main limitations of conventional reusable ureteroscopes. However, studies on the performance of the most recently developed models of single-use flexible ureteroscopes are scarce. This study aimed to compare the in vitro performance of several recently introduced, single-use, flexible ureteroscopes. METHODS: Five disposable flexible ureteroscopes were tested in vitro to evaluate their mechanical and optical characteristics. To this end, their degrees of deflection, irrigation flow rates, and image qualities were investigated. The models examined were Innovex US31-B12, OTU-100RR, Redpine RP-U-C12, Sciavita SUV-2A-B, and Seplou URS3016E. Their performance was also compared with that of a reusable flexible ureteroscope, Olympus URV-F. RESULTS: The OTU device had the highest degrees of deflection and the smallest loop diameter of the disposable ureteroscopes. The single-use ureteroscopes had identical image resolutions at a distance of 1 cm. The Innovex and Redpine devices had the best color representation. CONCLUSIONS: Of the tested disposable ureteroscopes, the OTU device had the best mechanical attributes, given its small loop diameter, high deflection angles, and low irrigation flow loss. As to their optical properties, the resolutions of all 5 single-use models were identical at an image distance of 1 cm.

The effect of laser fiber on the damage of the working channel of a flexible ureteroscope.

INTRODUCTION: Flexible ureteroscopy involves expensive equipment that is expensive to repair. This study aimed to investigate the effects of cleavage by various tools on the laser fiber tip and to determine the extent of damage incurred to the laser passing through the working channel and firing at different degrees of deflection. MATERIALS AND METHODS: We investigated the effect of cleavage on Lumenis Slimline reusable fibers (272 and 365 µm) as performed by four cleavage tools: a scribe pen, a surgical blade, suture scissors, and ceramic scissors. Following cleavage, we recorded the pattern of light dispersion and power output. The laser fibers passed through the working channel at various. RESULTS: The ceramic scissors provided the best pattern of light dispersion and the highest power output. The suture scissors provided unacceptable levels of light dispersion. The 272 µm fiber was able to pass through the working channel at 30 and 45 degrees of deflection. The 365 µm laser fiber was only able to pass through the working channel at 30 degrees of deflection. There was no breakage of the laser fiber at any of the degrees of deflection evaluated. CONCLUSIONS: Analysis showed that the ceramic scissors were the best tool for cleaving Lumenis Slimline reusable fibers and that suture scissors were unacceptable. We also found that the deflection angle that causes damage to the working channel by laser insertion is dependent on both the size of the laser fiber and the degree of bending. Firing the laser during scope deflection could be performed safely at any degree of deflection, even with a high laser power of 40 W for a duration of 30 s.

The Application of Retrograde Intrarenal Surgery to Remove a Single Large Kidney Stone During Pregnancy.

PURPOSE: To report the application and outcome of retrograde intrarenal surgery (RIRS) to remove a large kidney stone during pregnancy. PATIENT AND METHODS: A 30-year-old woman presented with an infected kidney stone (3 cm in size) at 4 weeks of pregnancy. We decided to remove the stone due to the possibility of obstruction and infection and chose to carry out this procedure by RIRS. In order to avoid complications associated with anesthetic, the surgery was carried out after the infection had cleared and when the patient had entered the second trimester of pregnancy. First, we used an ureteral access sheath and semi-rigid ureteroscopy to evaluate the ureteral lumen. We confirmed that the ureteral access sheath had been positioned appropriately by direct visualization with a flexible ureterorenoscope. The procedure was then carried out with a radiation-free protocol and without fluoroscopy. Ho-YAG laser lithotripsy was used to fragment the stones, and these fragments were then removed in a stone basket. The patient required three sessions of RIRS to remove the stone in its entirety; during this time, the patient was 18-29 weeks into her pregnancy. During each session, we removed approximately 30% of the stone. The patient developed fever after the first operation but responded fully to antibiotics. There were no perioperative complications, and the patient only remained in hospital for 3 days. The male infant was delivered by caesarian section at 37 weeks of pregnancy without any health complications. RESULTS AND CONCLUSION: We successfully removed a large kidney stone from a pregnant patient using an ureteral access sheath and RIRS without fluoroscopy. There were no complications indicating that this procedure can be carried out safely during pregnancy.

The correlation between demographic factors and upper urinary tract stone composition in the Thai population.

OBJECTIVE: To identify the correlation between demographic factors and upper urinary tract stone composition in the Thai population. METHOD: A retrospective observational study of first-time upper urinary tract stone former patients aged over 18 years who underwent stone surgery was performed in a tertiary referral university hospital from January 2013 to May 2018. Collected data included demographic information and stone composition information, which were analysed by the Fourier Transform-Infrared Spectroscopy (FTIR) method. The correlation between the demographic factors and major upper urinary tract stone composition was analysed using Fisher's exact test. RESULTS: A total of 480 patients were included in this study. The stones were 319 (66.5%) renal calculi and 161 (33.5%) ureteric calculi. There were 248 (51.7%) single composition stones and 232 (48.3%) mixed composition stones. The major stone compositions were 288 (60.0%) calcium oxalate (CaOx), 125 (26.0%) calcium phosphate (CaP), 40 (8.3%) uric acid (UA), 19 (4.0%) magnesium ammonium phosphate (MAP), five (1.0%) cystine, and three (0.6%) ammonium hydrogen urate (AHU). Gender was correlated with the major stone composition. In females, a correlation was found between the major stone composition and age, diabetes mellitus (DM), and glomerular filtration rate (GFR). The study showed no significant correlation between the major stone composition and dyslipidemia (DLP), hypertension (HT), gout, and body mass index (BMI) in both genders. CONCLUSION: Gender, age, DM, and GFR were the factors affecting the stone composition.

Vaporizing Effect of the Popcorn Technique for Laser Lithotripsy: Comparing the Different Settings of High Energy in a Caliceal Model.

Objective: To assess the effectiveness of laser lithotripsy in different holmium:yttrium aluminum garnet (Ho-YAG) laser settings with a wide range of energies, frequencies, and power. Materials and Methods: Two types of phantom stones were utilized, including soft stone, which mimics uric acid stone, and hard stone, which mimics calcium oxalate monohydrate stone. The stones were made into a round shape measuring 10 mm in diameter. The lithotripsy settings were 1 J × 20 Hz, 2 J × 10 Hz, 1.5 J × 20 Hz, 3 J × 10 Hz, and 2 J × 20 Hz. The lithotripsy was conducted in a caliceal model with a 2-mm filter. All stone vanishing from the artificial calix was an end point of the experiment. All fragments that passed through the filter of each setting were dried and weighed to calculate the vaporizing effect as well as to compare among the different settings. Laser fiber degradation was compared by using these settings. Results: Disintegration efficiency was determined by time consumption and the amount of vaporized stone. The best time consumption was 8 min 51 sec for 2 J × 20 Hz for hard stone and 5 min 13 sec for this setting for soft stone. The most vaporizing effect for hard stone was 92.19% for 2 J × 20 Hz and 87.30% for this setting for soft stone. The most fiber tip degradation was 28 mm for 3 J × 10 Hz for hard stone and 4 mm for 1.5 J × 20 Hz for soft stone. Conclusion: The study revealed that the best setting for hard stone was 2 J × 20 Hz, which was the fastest for achieving maximum vaporization, whereas fiber degeneration was comparable to others. For soft stone, there was no difference among the settings.

Characterization of renal stone composition by using fast kilovoltage switching dual-energy computed tomography compared to laboratory stone analysis: a pilot study.

PURPOSE: To prospectively examine the diagnostic performance of fast kilovoltage switching dual-energy computed tomography (DECT) in characterization of in vivo renal stone composition compared with postoperative stone analysis. METHODS: Consecutive consenting patients scheduled for endoscopic kidney stone surgery in a tertiary referral hospital from June 2015 to January 2016 were enrolled. Patients were preoperatively scanned with single-source, fast kilovoltage switching DECT. Stone compositions were determined regarding the effective atomic number measurements. Results of the stone compositions from DECT were compared to postoperative infrared spectroscopy stone analysis as the standard reference. RESULTS: For the 39 patients enrolled in the study, DECT was able to detect uric acid stone with sensitivity of 88.9% and specificity of 100%. There was 100% positive predictive value, 96.8% negative predictive value, and 97.4% accuracy. For non-contrast CT scan, sensitivity was 88.9%, specificity was 96.7%, positive predictive value was 88.9%, negative predictive value was 96.7%, and accuracy was 94.8%. Of the 39 samples examined, 21 (54%) were single composition, whereas 18 (46%) were combined. Single composition stones were correctly characterized by DECT in 100% (8/8) for uric acid. Whereas the result of uric acid stone containing stone discrimination in mixed composition was not so good with Zeff alone, iodine imaging can compensated this fault. CONCLUSIONS: DECT provides excellent accuracy in characterizing uric acid stone compositions. With the addition of iodine image, all of uric acid-containing stones can be determined by the DECT.