Laser Fiber Displacement Velocity during Tm-Fiber and Ho:YAG Laser Lithotripsy: Introducing the Concept of Optimal Displacement Velocity

Background: Endocorporeal laser lithotripsy (EL) during flexible ureteroscopy (URS-f) often uses “dusting” settings with “painting” technique. The displacement velocity of the laser fiber (LF) at the stone surface remains unknown and could improve EL’s ablation rates. This in vitro study aimed to define the optimal displacement velocity (ODV) for both holmium:yttrium-aluminium-garnet (Ho:YAG) and thulium fiber laser (Tm-Fiber). Methods: A 50W-TFL (IRE Polus®, Russia) and a 30W-MH1-Ho:YAG laser (Rocamed®), were used with 272µm-Core-Diameter LF (Sureflex, Boston Scientific©), comparing three TFL modes, “fine dusting” (FD:0.05–0.15 J/100–600 Hz); “dusting” (D:0.5 J/30–60 Hz); “fragmentation” (Fr:1 J/15–30 Hz) and two Ho:YAG modes (D:0.5 J/20 Hz, Fr:1 J/15 Hz). An experimental setup consisting of immerged cubes of calcium oxalate monohydrate (COM) stone phantoms (Begostone Plus, Begoã) was used with a 2 seconds’ laser operation time. LF were in contact with the stones, static or with a displacement of 5, 10 or 20 mm. Experiments were repeated four times. Stones were dried and µ-scanned. Ablation volumes (mm3) were measured by 3D-segmentation. Results: ODV was higher in dusting compared to fragmentation mode during Ho:YAG lithotripsy (10 mm/sec vs. 5 mm/sec, respectively). With Tm-Fiber, dusting and fragmentation OVDs were similar (5 mm/sec). Tm-Fiber ODV was lower than Ho:YAGs in dusting settings (5 mm/s vs. 10 mm/sec, respectively). Without LF displacement, ablation volumes were at least two-fold higher with Tm-Fiber compared to Ho:YAG. Despite the LF-DV, we report a 1.5 to 5-fold higher ablation volume with Tm-Fiber compared to Ho:YAG. Conclusions: In dusting mode, the ODVTm-Fiber is lower compared to ODVHo:YAG, translating to a potential easier Tm-Fiber utilization for “painting” dusting technique. The ODV determinants remain unknown. Dynamic ablation volumes are higher to static ones, regardless of the laser source, settings or LF displacement velocity.

Failure of ureteral access sheath insertion in primary flexible ureteroscopy for renal stones: is there any relation with inflammation?

Purpose To investigate the relationship between failure to insert a ureteral access sheath (UAS) with inflammation and other clinical parameters in patients treated with flexible ureteroscopy for renal stones. Methods This study included patients who underwent flexible ureteroscopy for the treatment of renal stones in our centre between 2015 and 2020. Patients who underwent any surgical procedure on the ipsilateral ureter and had a history of spontaneous stone passage were excluded. Patients were divided into two groups based on UAS insertion success (group 1) or failure (group 2). Both groups were compared with a view to clinical characteristics, preoperative neutrophil, lymphocyte, monocyte and platelet counts and ratios of these counts, all being considered inflammatory markers. A multivariate logistic regression analysis was performed to determine the independent variables affecting UAS insertion success. Results There were 113 (59.1%) patients in group 1, while group 2 consisted of 78 (40.9%) patients. The rates of male gender, coronary artery disease and preoperative ipsilateral hydronephrosis were significantly higher in group 2, while platelet counts and platelet-lymphocyte ratios were significantly lower. Our analysis revealed four independent predictors for UAS insertion failure: female gender (odds ratio [OR]=2.1) increased the rate of UAS insertion success, while hydronephrosis (OR=1.6), low platelet counts and PLR increased the rate of UAS insertion failure (OR=0.99, OR=0.98, respectively). Conclusion Our results suggest that male gender and ipsilateral hydronephrosis are associated with increased UAS insertion failure. Although we found a relationship between relatively low platelet levels and UAS insertion failure, we think that further studies are needed to investigate this matter.

Robotic Assisted Flexible Ureteroscopy in Covid-19 Positive Patient Using Thulium Fiber Laser: Case Report and Literature Review

Flexible Ureteroscopy (FURS) has become an integral aspect of the surgical armamentarium to treat intra-renal stones that are less than 2 cm in diameter. Despite the progress made with regards to the design of the flexible ureteroscopes, surgeons still need to work with suboptimal ergonomics, which may result in orthopedic complaints, which as a result lead to imperfect performance. Robotic- Assisted FURS with Avicenna Roboflex has provided significant improvement of ergonomics. The Super Pulse Thulium Fiber Laser (SPTFL) may be considered as a viable alternative to holmium laser in stone management. Coronavirus Disease- 19 (Covid-19) has been declared as a pandemic by the World Health Organization (WHO) on March 11, 2020. As a result, many hospitals have been converted to dedicated facilities to manage the Covid-19 patients. Urinary stone disease represents a benign condition, but in non-negligible number of cases, it can lead to potential severe septic complications that could increase the burden on emergency services. Many surgical specialties including urology has made short pathways for patient flow to decrease the contact with the patients which in turn will decrease the possibility of transmission of Covid-19. The use of new technologies such as Avicenna Roboflex and thulium fiber laser in Covid-19 positive patients when performing flexible ureteroscopy can minimize direct contact with the patient, expedite the procedure, while protecting the staff from getting Covid-19 infection.

Symptomatic renal papillary varicosities and medullary nephrocalcinosis

Background Nephrocalcinosis is often asymptomatic but can manifest with renal colic or hematuria. There is no reported association between nephrocalcinosis and renal vascular malformations, which may also be a source of hematuria. We herein present a case of a patient with hematuria related to nephrocalcinosis and renal papillary varicosities. These varicosities were diagnosed and successfully treated with flexible ureteroscopy and laser fulguration. Case presentation A 24-year-old female with a history of epilepsy (on zonisamide), recent uncomplicated pregnancy, and new diagnosis of nephrocalcinosis presented with right flank pain and intermittent gross hematuria. Imaging revealed intermittent right sided hydronephrosis. A cystoscopy identified hematuria from the right ureteral orifice. Diagnostic flexible ureteroscopy revealed numerous intrapapillary renal stones and varicose veins of several renal papillae. A 200 μm holmium laser fiber was used to unroof these stones and fulgurate the varicosities with resolution of her symptoms for several months. She later presented with left-sided symptoms and underwent left ureteroscopy with similar findings and identical successful treatment. Conclusion Unilateral hematuria from discrete vascular lesions of the renal collecting system may be obscured by other benign co-existing conditions, such as nephrocalcinosis and nephrolithiasis. Although a simultaneous presentation is rare, flexible ureteroscopy with laser fulguration offers an ideal diagnostic and therapeutic modality for these concurrent conditions if symptoms arise.

Outcome of Rirs for Renal Pelvic Stones 1.5 to 2.0 cm using Semi-Rigid Uretero-Renoscopy

Background Retrograde Intrarenal Surgery (RIRS) is among the recommended treatment modality for stones located in renal pelvis and is of less than 2 cm. Renal Stones with Hounsfield units more than 1000 have low stone free rate with ESWL. Objective To determine the outcome of retrograde intrarenal surgery using semirigid ureteroscope in fragmentation of renal pelvic stone. Methods Patients with 1.5-2.0 cm stone located in renal pelvis of more than 1000 HU who underwent retrograde intrarenal surgery as primary procedure at Sindh Institute of Urology And Transplantation were included. Stone fragmentation was achieved with holmium-yttrium aluminum garnet laser. Secondary procedure was performed if complete stone fragmentation was not achieved. Statistical analysis was performed by SPSS version 20. Result Total 82 patients with mean size of pelvic renal stones 1.7 ± 0.53 cm were included. The mean operating time was 32.1±12.9 mins. The stone clearance rate at six weeks after the first procedure was 79.3%. Minor complications including flank pain, fever and hematuria were reported. Conclusion Retrograde intrarenal surgery performed with semi rigid ureteroscope in renal pelvic stones of more than 1000 HU is a technically safe and effective procedure. Keywords: Retrograde intrarenal surgery; Pelvic stone; Flexible ureteroscopy and holmium laser.

Design and Performance Investigation of a Robot-Assisted Flexible Ureteroscopy System

Flexible ureteroscopy (FURS) has been developed and has become a preferred routine procedure for both diagnosis and treatment of kidney stones and other renal diseases inside the urinary tract. The traditional manual FURS procedure is highly skill-demanding and easily brings about physical fatigue and burnout for surgeons. The improper operational ergonomics and fragile instruments also hinder its further development and patient safety enhancement. A robotic system is presented in this paper to assist the FURS procedure. The system with a master-slave configuration is designed based on the requirement analysis in manual operation. A joint-to-joint mapping strategy and several control strategies are built to realize intuitive and safe operations. Both phantom and animal experiments validate that the robot has significant advantages over manual operations, including the easy-to-use manner, reduced intraoperative time, and improved surgical ergonomics. The proposed robotic system can solve the major drawbacks of manual FURS. The test results demonstrate that the robot has great potential for clinical applications.

The Outcomes of Pre-Stenting on Renal and Ureteral Stones: A Meta-Analysis

<b><i>Background:</i></b> Pre-stenting (PS) on the outcomes of semirigid and flexible ureteroscopic lithotripsy for a different upper urinary urolithiasis remains controversial. We performed a meta-analysis comparing the outcomes of ureteroscopic lithotripsy between PS and non-PS. <b><i>Materials and Methods:</i></b> Randomized, controlled trials and observational studies comparing PS and non-PS were identified from electronic databases. Stone-free rate (SFR), operative time, and complications were compared by qualitative and quantitative syntheses (meta-analyses). <b><i>Results:</i></b> Eleven articles were included in this study. Nearly, all of recently published studies exhibited relatively moderate or high quality during quality assessment. PS was more likely to achieve good SFR compared with non-PS (<i>p</i> &#x3c; 0.00001). The subgroup results indicated that PS improved the SFR for renal stones and the stones dealt by flexible ureteroscopy (<i>p</i> = 0.0002; <i>p</i> &#x3c; 0.0001, respectively; some ureteral stones were dealt by flexible ureteroscopy). Ureteral stones and the stones dealt by semirigid ureteroscopy were not influenced by PS (<i>p</i> = 0.62; <i>p</i> = 0.90, respectively). PS is equal as non-PS in terms of operative time for renal stones and the renal and ureteral stones dealt by flexible ureteroscopy (<i>p</i> = 0.47; <i>p</i> = 0.05). No significant difference was found in major complications between the 2 groups for total or for the subgroup of renal stones (<i>p</i> = 0.3; <i>p</i> = 0.69). <b><i>Conclusions:</i></b> For ureteral stones or the stones dealt by semirigid ureteroscopy, PS does not show any benefits. For renal stones or the stones dealt by flexible ureteroscopy, PS improves the SFR and may be as safe as non-PS.