Proof-of-concept for a novel nanotechnology-based treatment for urolithiasis

Proof-of-concept of photonic lithotripsy in an in vitro setting and its ability to fragment the most common stone types is demonstrated. Effectiveness of different classes of photonic nanoparticles in fragmenting human stones is assessed. De-identified human stones were collected after institutional approval. Stones of a size range between 2-4 mm were rehydrated in simulated urine for 24 h. Stones were then coated with a solution of nanoparticles prior to activation with either a 785 nm or 1320 nm near-infrared energy source. Photonic lithotripsy achieved greater than 70% success rate in fragmentating calcium oxalate monohydrate stones using carbon-based nanoparticles for both near-infrared wavelengths. For gold-based nanoparticles, there was a similar success rate with the 785 nm wavelength but a significant decrease when using the 1320 nm wavelength energy source. All stones fragmented with the energy source at a distance ≥ 20 mm from the stone's surface. Limitations include the use of mixed-composition stones, a lack of complete stone immersion in liquid during treatment, and smaller stone size. Different classes of nanoparticles when excited with a near-infrared energy source can fragment common stone types in vitro. This technology has the potential to change the way we approach and treat patients with urolithiasis in a clinical setting.

Flexible ureteroscopic treatment of kidney stones: How do the new laser systems change our concepts?

Objective

Flexible ureteroscopy (fURS) has become a widely accepted and effective technique for treating kidney stones. With the development of new laser systems, the fURS approach has evolved significantly. This literature review aims to examine the current state of knowledge on fURS treatment of kidney stones, with a particular focus on the impact of the latest laser technologies on clinical outcomes and patient safety.

Methods

We conducted a search of the PubMed/PMC, Web of Science Core Collection, Scopus, Embase (Ovid), and Cochrane Databases for all randomized controlled trial articles on laser lithotripsy in September 2023 without time restriction.

Results

We found a total of 22 relevant pieces of literature. Holmium laser has been used for intracavitary laser lithotripsy for nearly 30 years and has become the golden standard for the treatment of urinary stones. However, the existing holmium laser cannot completely powder the stone, and the retropulsion of the stone after the laser emission and the thermal damage to the tissue have caused many problems for clinicians. The introduction of thulium fiber laser and Moses technology brings highly efficient dusting lithotripsy effect through laser innovation, limiting pulse energy and broadening pulse frequency.

Conclusion

While the holmium:yttrium-aluminum-garnet laser remains the primary choice for endoscopic laser lithotripsy, recent technological advancements hint at a potential new gold standard. Parameter range, retropulsion effect, laser fiber adaptability, and overall system performance demand comprehensive attention. The ablation efficacy of high-pulse-frequency devices relies on precise targeting, which may pose practical challenges.

Holmium:YAG laser-assisted intraductal sialendoscopic lithotripsy under local anesthesia

OBJECTIVES

This retrospective multi-institutional chart review study aims to present results from patients treated with Holmium:YAG laser-assisted sialendoscopic intraductal lithotripsy under local anesthesia.

METHODS

Preoperative ultrasound and/or CT were used for location and measurement of the stones. Local anesthesia was applied in all patients, Marchal all-in- one 1.3 mm and Erlangen 1.6 sialendoscopes were used. The laser was used with power settings limited by discomfort or pain. Inclusion criteria were stone size (all >5 mm) and fixed stones.

RESULTS

42 patients, 48 stones were treated (30 males/12 females), 21 submandibular and 21 parotid. Ages ranged from 20 to 70 years (95 % CI: 43.37-51.58). Mean size was 6.2 mm (95 % CI: 5.71-6.72). Complete fragmentation was achieved in 66.7 % and incomplete in 33.3 %. Out of the incomplete fragmented 14 cases, seven (50 %) remained symptom free on follow-up. Maximum duration was 120 min. Minimum power settings of the laser was 4.8 Watts and maximum 18 Watts. Six patients expressed pain or discomfort that limited power increase and duration of the procedure. Total follow up time was 10 years. There were no major complications such as hemorrhage, nerve paresis or skin ulceration.

CONCLUSION

The procedure is safe under local anesthesia, well tolerated by most patients and should be used in cases of small fixed and "intermediate-sized" stones as a single modality. Discomfort may limit power settings and duration. The later is the major disadvantage of the method.

Getting hot in here! Comparison of Holmium vs. thulium laser in an anatomic hydrogel kidney model

As laser technology has advanced, high-power lasers have become increasingly common. The Holmium: yttrium-aluminum-garnet (Ho:YAG) laser has long been accepted as the standard for laser lithotripsy. The thulium fiber laser (TFL) has recently been established as a viable option. The aim of this study is to evaluate thermal dose and temperature for the Ho:YAG laser to the TFL at four different laser settings while varying energy, frequency, operator duty cycle (ODC). Utilizing high-fidelity, 3D-printed hydrogel models of a pelvicalyceal collecting system (PCS) with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Ho:YAG laser or TFL. At a standard power (40W) and irrigation (17.9 ml/min), we evaluated four different laser settings with ODC variations with different time-on intervals. Temperature was measured at two separate locations. In general, the TFL yielded greater cumulative thermal doses than the Ho:YAG laser. Thermal dose and temperature were typically greater at the stone when compared away from the stone. Regarding the TFL, there was no general trend if fragmentation or dusting settings yielded greater thermal doses or temperatures. The TFL generated greater temperatures and thermal doses in general than the Ho:YAG laser with Moses technology. Temperatures and thermal doses were greater closer to the laser fiber tip. It is inconclusive as to whether fragmentation or dusting settings elicit greater thermal loads for the TFL. Energy, frequency, ODC, and laser-on time significantly impact thermal loads during ureteroscopic laser lithotripsy, independent of power.

WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model

PURPOSE

To evaluate the thermal profiles of the holmium laser at different laser parameters at different locations in an in vitro anatomic pelvicalyceal collecting system (PCS) model. Laser lithotripsy is the cornerstone of treatment for urolithiasis. With the prevalence of high-powered lasers, stone ablation efficiency has become more pronounced. Patient safety remains paramount during surgery. It is well recognized that the heat generated from laser lithotripsy has the potential to cause thermal tissue damage.

METHODS

Utilizing high-fidelity, 3D printed hydrogel models of a PCS with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40 W) and irrigation pressure (100 cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations-at the stone and away from the stone.

RESULTS

Temperatures were highest closest to the laser tip with a decrease away from the laser. Fluid temperatures increased with longer laser-on times and higher ODCs. Thermal doses were greater with increased ODCs and the threshold for thermal injury was reached for ODCs of 75% and 100%.

CONCLUSION

Temperature generation and thermal dose delivered are greatest closer to the tip of the laser fiber and are not dependent on power alone. Significant temperature differences were noted between four laser settings at a standardized power (40 W). Temperatures can be influenced by a variety of factors, such as laser-on time, operator duty cycle, and location in the PCS.

Comparison of lithotripsy methods during mini-PNL: is there a role for ballistic lithotripsy in the era of high-power lasers

BACKGROUND

For renal stones > 20 mm, percutaneous nephrolithotomy (PNL) offers the best stone clearance rates with acceptable complication rates. This study aimed to compare the efficiency of high-power holmium YAG laser and ballistic lithotripsy during mini-PNL.

METHODS

Data from 880 patients who underwent mini-PNL for renal stones was investigated retrospectively. The study utilized propensity score matching to create two groups: laser lithotripsy (n = 440) and ballistic lithotripsy (n = 440). The groups were matched based on stone size, Guy's stone score, and stone density. The main objectives of the study were to assess the stone-free rate (SFR), duration of surgery, and complication rates.

RESULTS

The average age of the population was 51.4 ± 7.1 years, with a mean stone size of 28.6 ± 8.3 mm and a mean stone density of 1205 ± 159 HU. There were no significant differences between the groups. The SFRs of the laser lithotripsy and ballistic lithotripsy were 92.5% and 90.2%, respectively (p = 0.23). The laser lithotripsy group had a notably shorter surgery time (40.1 ± 6.3 min) compared to the ballistic lithotripsy group (55.6 ± 9.9 min) (p = 0.03). Complication rates were similar (p = 0.67).

CONCLUSIONS

Our study shows that a high-power holmium YAG laser provides quicker operation time compared to ballistic lithotripsy. However, ballistic lithotripsy is still an effective and safe option for stone fragmentation during mini-PNL. In places where a high-power holmium YAG laser is not available, ballistic lithotripters are still a safe, effective, and affordable option for mini-PNL.

Retrograde Intrarenal Surgery for Renal Stones: Is It a Safe and Effective Option in Preschool Children?

INTRODUCTION

Few studies in the literature describe the Retrograde Intra-Renal Surgery (RIRS) outcome in preschool children. We evaluated the feasibility, stone-free rate and complications of RIRS in preschool children at two European tertiary care centres of Pediatric Urology.

MATERIAL AND METHODS

The retrospective study includes all children undergone RIRS for stones <25 mm from 2017 to 2022. Patients were divided into Group 1 <5 years (G1) and Group 2 >5 years (G2). Semirigid ureterorenoscope 4.5-6.5 Ch and a 7.5 Fr flexible ureteroscope with a 9.5/11 Ch ureteral access sheath (UAS) were used. Stone-free rate (SFR) was evaluated at 3 months. Fischer/Chi-square test for qualitative data and Mann-Whitney for quantitative data were used for statistical analysis.

RESULTS

63 patients underwent RIRS, 19 G1-patients, median age 3.55 ± 1.06 years (range 1.5-5 years), and 44 G2-patients, median age 11.25 ± 2.95 (range 6-17 years) (p < 0.00001). Intraoperative complications occurred in 1 case in G1(5%) and 3 in G2(7%) (p = 1): two minor ureteric injuries in G2 were treated by a prolonged JJ-stent. Postoperative fever was reported in 3 cases in G1 (16%) and 4 in G2(9%) (p = 0.42), while post-operative hematuria in 4 G1-patients (21%) and in 7 G2-patients (16%) (p = 0.72). SFR was 84.2% in G1 and 88.6% in G2. At an average follow-up of 15.05 ± 4.83 months in G1 and 19.95 ± 10.36 months in G2, reintervention for residual stones was necessary in 3 cases in G1(16%) and in 6 cases in G2(14%) (p = 1).

CONCLUSIONS

In a European country with low-volume pediatric stone centers, RIRS is a promising therapeutic option in young children as it offers acceptable stone-free rate and a low incidence of high-grade complications.

LEVEL OF EVIDENCE

III.

Ho:YAG laser and dusting-high power vs low power: there is no difference

The introduction of the Ho:YAG laser 3 decades ago revolutionized the endoscopic treatment of urolithiasis. Since then, a variety of innovations have continued to evolve these devices, including the development of high-power lasers capable of high-frequency lithotripsy. The clinical utility of high-frequency lithotripsy, however, has not necessarily lived up to the potential suggested by in vitro studies. A review of the relevant literature, confirming strong similarities between the outcomes associated with high and lower power laser lithotripsy, follows.

Performance of brushite plaster as kidney stone phantoms for laser lithotripsy

Artificial phantoms used in photothermal near-infrared laser lithotripsy research generally fail to mimic both the chemical and the physical properties of human stones. Though high-energy, 1 J pulses are capable of fracturing hard human stones into several large fragments along natural boundaries, similar behavior has not been observed in commonly used gypsum plasters like BegoStone. We developed a new brushite-based plaster formulation composed of ≈90% brushite that undergoes rapid fracture in the manner of human stones under fragmentation pulse regimes. Single-pulse (1 J) ablation crater volumes for phantoms were not significantly different from those of pure brushite stones. Control over crater volumes was demonstrated by varying phosphorous acid concentration in the plaster formulation. Fragmentation of cylindrical brushite phantoms was filmed using a high-speed camera which demonstrated rapid fragmentation in < 100 µs during the bubble expansion phase of a short pulse from a high-powered Ho:YAG laser (Lumenis Pulse 120 H). The rapid nature of observed fracture suggests increasing laser pulse energy by increasing laser pulse duration will not improve fragmentation performance of laser lithotripters. Brushite plaster phantoms are a superior alternative to gypsum plasters for laser lithotripsy research due to their better mimicry of stone composition, controllable single-pulse crater volumes, and fragmentation behavior.

Femtosecond laser lithotripsy: a novel alternative for kidney stone treatment? Evaluating the safety and effectiveness in an ex vivo study

The Holmium (Ho:YAG) laser is presently the most extensively employed in laser lithotripsy for the management of kidney stones. Despite its adoption as the gold standard for laser lithotripsy, Ho:YAG laser lithotripsy poses three significant challenges, namely thermal effect, insufficient stone fragmentation, and stone displacement, which have garnered increased attention from urologic surgeons. Nowadays, the femtosecond laser is regarded as a potential alternative to the Ho:YAG laser due to its capacity to ablate diverse materials with minimal thermal effect. In our ex vivo investigation, we assessed the dimensions of ablation pits, the efficacy of ablation, the degree of stone fragmentation, the alterations in water temperature surrounding stones, and the degree of tissue damage associated with Femtosecond laser lithotripsy utilizing adjustable power settings (1-50 W). Our findings indicate that the ablation pits generated by the Femtosecond laser exhibited uniform geometries, and the effectiveness of ablation and fragmentation for Femtosecond laser lithotripsy were significantly and positively correlated with laser power. When the laser power remained constant, the Femtosecond laser with higher pulse energy demonstrated superior efficiency in stone ablation, but inferior performance in stone fragmentation. Conversely, the Femtosecond laser with higher pulse frequency exhibited the opposite behavior. Furthermore, the thermal effect increased proportionally with laser power, leading to a tentative recommendation of 10W laser power for future investigations. Our in vitro findings suggest that the Femtosecond laser holds promise as a safe and effective alternative to holmium lasers.

Dusting efficacy between the regular setting of holmium laser (Ho:YAG) versus Vapor Tunnel pulse modality for non-complex kidney stones

The new pulse modality Vapor-Tunnel™ (VT) consists of a very long pulse that uses the minimum peak power, causing the energy to pass through a previously created vapor channel or tunnel. The first part of the pulse creates a vapor channel, whereas the remaining energy is discharged immediately after, passing straight through the previously created tunnel. The aim of this study is to compare the dusting efficacy between Ho:YAG laser with long pulse and Ho:YAG laser with VT for non-complex kidney stones. A retrospective comparative study of 236 patients who underwent retrograde intrarenal surgery using Ho:YAG laser (long pulse vs. VT) was performed. Stone size, stone density, laser settings, laser emission time, and total operative time were recorded. We also assessed the lithotripsy efficacy (J/mm3). The stone-free rate was defined as the absence of stone fragments in a non-contrast abdominal computed tomography 4 weeks after the procedure. A total of 118 patients were included in each group. There was no significant difference in age, gender, and body mass index. Median stone volume (737 mm3 vs. 636 mm3) and stone density (788 HU vs. 656 HU) were higher in the VT group. Total energy used (14.5 J vs. 18.2 J), the laser emission time (20 min vs. 26 min), and the total operative time (79.5 min vs. 95 min) were significantly lower in the VT group. The stone-free rate was comparable between both groups (74.5% for VT and 66.1% for the long-pulse group, p = 0.15). When we evaluated the efficacy of laser lithotripsy, a significantly lower difference was obtained in the VT group (median 12.5 J/mm3 vs. median 23.1 J/mm3). The VT pulse modality was associated with decreased laser time and operative time. Additionally, it increased lithotripsy efficacy compared to Ho:YAG long pulse laser, but with a comparable free-stone rate.

Different ureteral access sheaths sizes for retrograde intrarenal surgery

PURPOSE

There is a trend toward miniaturization in endourological stone therapy. Good visibility, intrarenal pressures and temperature control should be ensured by ureteral sheaths. In the context of the present study, 10/12 Charr. sheaths and 12/14 Charr. sheaths for flexible ureterorenoscopy were investigated regarding stone-free rate, complication rate and efficacy for laser lithotripsy.

METHODS

From January 2020 to January 2022, 100 patients each with kidney stone up to 1.5 cm in diameter were included in the study. Use of a 12/14 Charr. vs. 10/12 Charr. ureteral sheath for flexible ureterorenoscopy was compared. Perioperative data, stone size, volume and density, laser energy, laser duration, stone-free rates and complications based on Clavien-Dindo classification were retrospectively analyzed.

RESULTS

For both groups of ureteral access sheaths, there were no differences in median surgery duration (10/12 Charr: 29 min (7-105 min) vs. 12/14 Charr: 34 min (9-95 min); p = 0.33), overall complication rate (p = 0.61) and hospitalization (p = 0.155). There were no differences in stone-free rates (97.9% vs. 92.7%, p = 0.37). Laser lithotripsy duration usingholmium laser was 1.9 min (0.1-10.8 min) vs. 3.8 min (0.2-20.7 min) (p < 0.01) and applied laser energy was 3.1 J (0.15 J-10.29 J) vs. 6.8 J (1.07 J-26.77 J) (p < 0.01) for 12/14 Charr. sheaths and 10/12 Charr. sheaths, respectively.

CONCLUSION

In terms of stone-free rates, there are no differences between the 10/12 and 12/14 Charr. ureteral access sheaths. The laser duration and energy was increased with 10/12 Charr. sheaths without showing increased risk for clinical complications like trauma or inflammation.

The predictive factors that total laser energy consumed during retrograde intrarenal surgery (RIRS): stone area and density

Holmium: YAG (Ho: YAG) laser lithotripsy with flexible ureterorenoscopy can be used with high stone-free and low complication rates for renal stones. This study aimed to determine the factors affecting the total laser energy in cases with provided stone-free status after a single session of retrograde intrarenal surgery (RIRS). Data of 222 patients who underwent RIRS between October 2017 and March 2020 were evaluated retrospectively. After exclusion criteria, the study was carried out with 184 stone-free cases. All cases were performed without using a ureteral access sheath (UAS), and dusting was preferred as the lithotripsy method. The effects of age, gender, body mass index (BMI), previous RIRS history, previous shock wave lithotripsy (SWL) history, stone localization, number of stones, stone surface area, and stone density on total laser energy were analyzed. There was no significant correlation between total laser energy with gender, BMI, previous RIRS history, previous SWL history, stone localization, and the number of stones (p:0.347, p:0.482, p:0.119, p:0.167, p:0.907, p:0.933 respectively). There was a significant correlation between age and total laser energy (p = 0.032), but it was not observed when the effect of the stone surface area was removed (p = 0.354). There were significant correlations between total laser energy and stone surface area, stone density, and total laser time (p<0.001, p<0.001, and p <0.001, respectively). Stone area and stone density affect the total energy consumed during laser lithotripsy. Urologists should consider the stone area, stone density, and the power of the laser device to determine which surgical technic to prefer.

Prospective Comparison of Thulium and Holmium Laser Lithotripsy for the Treatment of Upper Urinary Tract Lithiasis

Background

Lithotripsy with holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the current gold standard for treating stones of the upper urinary tract (UUT). The recently introduced thulium fiber laser (TFL) has the potential to be more efficient and as safe as Ho:YAG.

Objective

To compare the performance and complications between Ho:YAG and TFL for UUT lithotripsy.

Design setting and participants

This was a prospective single-center study of 182 patients treated between February 2021 and February 2022. In a consecutive approach, laser lithotripsy was performed via ureteroscopy with Ho:YAG for 5 mo, and then with TFL for 5 mo.

Outcome measurements and statistical analysis

Our primary outcome was stone-free (SF) status at 3 mo after ureteroscopy with Ho:YAG versus TFL lithotripsy. Secondary outcomes were complication rates and results regarding the cumulative stone size. Patients were followed at 3 mo with abdominal imaging (ultrasound or computed tomography).

Results and limitations

The study cohort comprised 76 patients treated with Ho:YAG laser and 100 patients treated with TFL. Cumulative stone size was significantly higher in the TFL than in the Ho:YAG group (20.4 vs 14.8 mm; p = 0.01). SF status was similar in both groups (68.4% vs 72%; p = 0.06). Complication rates were comparable. In subgroup analysis, the SF rate was significantly higher (81.6% vs 62.5%; p = 0.04) and the operative time was shorter for stones measuring 1-2 cm, whereas the results were similar for stones <1 cm and >2 cm. The lack of randomization and single-center design are the main limitations of the study.

Conclusions

TFL and Ho:YAG lithotripsy are comparable in terms of the SF rate and safety for the treatment of UUT lithiasis. According to our study, for a cumulative stone size of 1-2 cm, TFL is more effective than Ho:YAG.

Patient summary

We compared the efficiency and safety of two laser types for the treatment of stones in the upper urinary tract. We found that stone-free status at 3 months did not significantly differ between the holmium and thulium lasers.

Long-term follow-up on dusting versus basketing during ureteroscopy: a prospective multicenter trial from the EDGE Research Consortium

In 2018, the Endourology Disease Group for Excellence (EDGE) published a prospective trial comparing dusting versus basketing during ureteroscopy. One hundred fifty-nine patients were included in the original analysis, which found no difference in stone-free rate at 3 months. We report the intermediate and long-term outcomes of patients included in the original trial. Two analyses were performed. At 1-year, a retrospective chart review was performed, and data collected on stone episodes, Emergency Department (ED) visits, hospital admissions and surgical interventions. To obtain long-term outcomes, the four sites with the largest initial accrual were included in a second phase of data collection with updated analyses. The patients from those sites were contacted, re-consented, and data were collected on stone surgical interventions, stone episodes, stone recurrences on imaging, emergency department (ED) visits, and hospital admissions for stone-related care since their original procedure. One-year follow-up data were collected in 111 of the original 159 (69.8%) patients from the nine sites. There were no statistically significant differences in the number of painful episodes, ED visits, hospital admissions, or surgical interventions. 94 patients from four sites were included in the long-term analysis. There were no statistically significant differences in surgical interventions, painful stone episodes, stone recurrence on imaging, ED visits or hospitalizations for stone-related events between the two groups. Long-term outcomes of dusting versus basketing during ureteroscopy indicate that there are no significant differences in clinical outcomes between the two surgical modalities.

The efficacy of retrograde intra-renal surgery (RIRS) for lower pole stones: results from 2946 patients

PURPOSE

To evaluate the perioperative outcomes of retrograde intra-renal surgery (RIRS) for lower pole stones (LPS) and factors affecting stone-free rate (SFR).

METHODS

Data from 20 centers were retrospectively reviewed. Inclusion criteria were adult patients, normal renal anatomy, and LPS. Exclusion criteria were bilateral surgery, concomitant surgery for ureteral stones. SFR was defined as a single residual fragment (RF) ≤ 2 mm and evaluated 3-months after surgery. A multivariable logistic regression analysis was performed to assess factors associated with RF. Statistical significance was set at p value < 0.05.

RESULTS

2946 patients were included. Mean age and stone size were 49.9 years 10.19 mm, with multiple LPS in 61.1% of cases. Total operation and laser time were 63.89 ± 37.65 and 17.34 ± 18.39 min, respectively. Mean hospital stay was 3.55 days. Hematuria requiring blood transfusion and fever/urinary infections requiring prolonged antibiotics occurred in 6.1% and 169 5.7% of cases, while sepsis with intensive-care admission in 1.1% of patients. On multivariate analysis, Multiple stones (OR 1.380), stone size (OR 1.865), and reusable ureteroscopes (OR 1.414) were significantly associated with RF, while Thulium fiber laser (TFL) (OR 0.341) and pre-stenting (OR 0.750) were less likely associated with RF.

CONCLUSIONS

RIRS showed safety and efficacy for LPS with a mean diameter of 10 mm. This procedure can achieve a satisfactory SFR in pre-stented patients with a single and smaller stone, particularly with TFL use.

[Recent progress in the treatment of intractable sialolithiasis]

Sialolithiasis occurs in approximately 0.45% to 1.20% of the general population. The typical clinical symptom manifests as a painful swelling of the affected glands after a meal or upon salivary stimulation, which extremely affects the life quality of the patients. With the development of sialendoscopy and lithotripsy, most sialoliths can be successfully removed with preservation of the gland. However, sialoliths in the deep hilar-parenchymal submandibular ducts and impacted parotid stones located in the proximal ducts continue to pose great challenges. Our research center for salivary gland diseases (in Peking University School and Hospital of Stomatology) has used sialendoscopy for 17 years and treated >2 000 patients with salivary gland calculi. The success rate was approximately 92% for submandibular gland calculi and 95% for parotid calculi. A variety of minimally invasive surgical techniques have been applied and developed, which add substantial improvements in the treatment of refractory sialolithiasis. Further, the radiographic positioning criteria and treatment strategy are proposed for these intractable stones. Most of the hilar-parenchymal submandibular stones are successfully removed by a transoral approach, including transoral duct slitting and intraductal basket grasping, while a small portion of superficial stones can be removed by a mini-incision in submandibular area. Impacted stones located in the distal third of parotid gland ducts are removed via "peri-ostium incision", which is applied to avoid a cicatricial stenosis from a direct ostium incision. Impacted parotid stones located in the middle and proximal third of the Stensen's duct are removed via a direct mini-incision or a peri-auricular flap. A direct transcutaneous mini-incision is commonly performed under local anesthesia with an imperceptible scar, and is indicated for most of impacted stones located in the middle third, hilum and intraglandular ducts. By contrast, a peri-auricular flap is performed under general anesthesia with relatively larger operational injury of the gland parenchyma, and should be best reserved for deeper intraglandular stones. Laser lithotripsy has been applied in the treatment of sialolithiasis in the past decade, and holmium ∶YAG laser is reported to have the best therapeutic effects. During the past 3 years, our research group has performed laser lithotripsy for a few cases with intractable salivary stones. From our experiences, withdrawal of the endoscopic tip 0.5-1.0 cm away from the extremity of the laser fiber, consistent saline irrigation, and careful monitoring of gland swelling are of vital importance for avoidance of injuries of the ductal wall and the vulnerable endoscope lens during lithotripsy. Larger calculi require multiple treatment procedures. The risk of ductal stenosis can be alleviated by endoscopic dilation. In summary, appropriate use of various endoscopy-assisted lithotomy helps preserve the gland function in most of the patients with refractory sialolithiasis. Further studies are needed in the following aspects: Transcervical removal of intraglandular submandibular stones, intraductal laser lithotripsy of impacted parotid stones and deep submandibular stones, evaluation of long-term postoperative function of the affected gland, et al.

Comparative analysis of ureteroscopic laser lithotripsy and extracorporeal shock wave lithotripsy in the treatment of childhood proximal ureteral stones

PURPOSE

This study aims to make a comparative analysis of the superiority of ESWL and URS in proximal ureteral stones in children.

METHODS

A total of 155 patients under the age of 15 were included in the study. The patients were divided into two groups as Group 1 (n = 80, ESWL) and Group 2 (n = 75, URS) according to the type of procedure performed. The patients in both groups were evaluated in terms of age, gender, lateralization, stone size, stone volüme, stone density, and preoperative hydronephrosis. In addition, both methods used were compared in terms of success rate, time, cost, hospitalization and complications.

RESULTS

The mean age were 7.4 ± 2.1 in Group-1 and 8.1 ± 1.8 in Group-2. Demographic, clinical and laboratory data of both groups were similar. The hospitalization time, procedure time, success rate and cost were significantly higher in Group-2. The complication rate was significantly higher in Group-2 (p < 0.001). There was a significant negative correlation between ESWL success and stone volume (ρ - 0.375, p = 0.001) and stone density (ρ - 0.283, p = 0.011).

CONCLUSION

ESWL can be performed as the first line treatment of proximal ureteral stones in children due to its daily use, low cost, short procedure time and low complication rate. Increasing stone volume and density reduces the success of ESWL.

Per-oral pancreatoscopy-guided lithotripsy vs. extracorporeal shock wave lithotripsy for treating refractory main pancreatic duct stones in chronic pancreatitis: Protocol for an open-label multi-center randomized clinical trial

BACKGROUNDS/OBJECTIVES

Patients with chronic pancreatitis may develop pancreatic duct stones that can obstruct outflow leading to ductal hypertension and pain. Both endoscopic retrograde pancreatography (ERP) with per-oral pancreatoscopy (POP) and intraductal lithotripsy and extracorporeal shock wave lithotripsy (ESWL) are feasible options to attempt ductal stone clearance. This study aims to compare POP-guided lithotripsy with ESWL in the management of refractory symptomatic main pancreatic duct stones.

METHODS

This is an open-label, multi-center, parallel, randomized clinical trial. Patients with chronic pancreatitis and main pancreatic duct stones ≥5 mm who fail standard ERP methods for stone removal will be eligible for this study. In total, 150 subjects will be randomized 1:1 to either ESWL or POP. A maximum of 4 sessions of either ESWL or POP will be allowed in each arm, with crossover permitted thereafter. The primary outcome is complete stone clearance and secondary outcomes include quality of life, pain scores, number of interventions, and daily opiate requirements.

CONCLUSIONS

This study aims to answer the question of which lithotripsy method is superior in removing refractory pancreatic duct stones while addressing the effects of lithotripsy on quality of life and pain in patients with chronic calcific pancreatitis (ClinicalTrials.gov NCT04115826).

Multi-class motion-based semantic segmentation for ureteroscopy and laser lithotripsy

Ureteroscopy with laser lithotripsy has evolved as the most commonly used technique for the treatment of kidney stones. Automated segmentation of kidney stones and the laser fiber is an essential initial step to performing any automated quantitative analysis, particularly stone-size estimation, that can be used by the surgeon to decide if the stone requires further fragmentation. However, factors such as turbid fluid inside the cavity, specularities, motion blur due to kidney movements and camera motion, bleeding, and stone debris impact the quality of vision within the kidney, leading to extended operative times. To the best of our knowledge, this is the first attempt made towards multi-class segmentation in ureteroscopy and laser lithotripsy data. We propose an end-to-end convolution neural network (CNN) based learning framework for the segmentation of stones and laser fiber. The proposed approach utilizes two sub-networks: (I) HybResUNet, a hybrid version of residual U-Net, that uses residual connections in the encoder path of the U-Net to improve semantic predictions, and (II) a DVFNet that generates deformation vector field (DVF) predictions by leveraging motion differences between the adjacent video frames which is then used to prune the prediction maps. We also present ablation studies that combine different dilated convolutions, recurrent and residual connections, atrous spatial pyramid pooling, and attention gate models. Further, we propose a compound loss function that significantly boosts the segmentation performance in our data. We have also provided an ablation study to determine the optimal data augmentation strategy for our dataset. Our qualitative and quantitative results illustrate that our proposed method outperforms state-of-the-art methods such as UNet and DeepLabv3+ showing a DSC improvement of 4.15% and 13.34%, respectively, in our in vivo test dataset. We further show that our proposed model outperforms state-of-the-art methods on an unseen out-of-sample clinical dataset with a DSC improvement of 9.61%, 11%, and 5.24% over UNet, HybResUNet, and DeepLabv3+, respectively in the case of the stone class and an improvement of 31.79%, 22.15%, and 10.42% over UNet, HybResUNet, and DeepLabv3+, respectively, in case of the laser class.

Development of an automated laser drilling algorithm to compare stone ablation patterns from different laser pulse modes

PURPOSE

To develop a novel automated three-dimensional (3D) laser drilling algorithm to further investigate laser-stone interaction with different laser pulse modes. Comparison of post-ablative lattice architecture combined with mass of stone ablated can provide a more complete understanding of differences between pulse mode.

METHODS

A 3D positioner (securing laser fiber) was programmed to create a 5 × 5 grid of drill holes spaced 1 mm apart on 15:5 cylindrical BegoStones. Beginning 0.5 mm above the stone surface, the laser fiber was activated and advanced 2 mm toward and into the stone for all 25 points. Four trials for each pulse mode [short pulse (SP), long pulse (LP), Moses Contact (MC), Moses Distance (MD)] were completed. Outcome measures were assessment of lattice preservation and mass of ablated stone.

RESULTS

MC exhibited the greatest lattice preservation and least stone mass ablated (50.5 ± 2.2 mg). SP (69.4 ± 4.3 mg) and MD (70.0 ± 2.6 mg) had the greatest lattice destruction and stone mass ablated. The differences in stone ablated between MC and MD (p = 0.00003), MC and SP (p = 0.0002), and LP and MD (p = 0.004) were statistically significant.

CONCLUSIONS

Consistent quantitative and qualitative differences between pulse modes were observed with a novel automated 3D laser drilling algorithm applied to BegoStone. The laser drilling algorithm developed here can be used to further enhance mechanistic understanding of laser-stone interactions and facilitate selection of appropriate laser pulse modes to balance precision and efficiency across the range of laser lithotripsy techniques.

Factors Influencing Performance of Cholangioscopy-Guided Lithotripsy Including Available Different Technologies: A Prospective Multicenter Study with 94 Patients

BACKGROUND

Peroral cholangioscopy (POC)-guided lithotripsy is an effective treatment for difficult biliary stones. A clear definition of factors associated with the efficacy of POC-guided lithotripsy in one session and the performance of electrohydraulic lithotripsy (EHL) and laser lithotripsy (LL) have not clearly emerged.

METHODS

This was a non-randomized prospective multicenter study of all consecutive patients who underwent POC lithotripsy (using EHL and/or LL) for difficult biliary stones. The primary endpoint of the study was the number of sessions needed to achieve complete ductal clearance and the factors associated with this outcome. Secondary endpoints included the evaluated efficacies of LL and EHL.

RESULTS

Ninety-four patients underwent 113 procedures of EHL or LL. Complete ductal clearance was obtained in 93/94 patients (98.94%). In total, 80/94 patients (85.11%) achieved stone clearance in a single session. In the multivariate analysis, stone size was independently associated with the need for multiple sessions to achieve complete ductal clearance (odds ratio = 1.146, 95% confidence interval: 1.055-1.244; p = 0.001). Using ROC curves and the Youden index, 22 mm was found to be the optimal cutoff for stone size (95% confidence interval: 15.71-28.28; p < 0.001). The majority of the patients (62.8%) underwent LL in the first session. Six patients failed the first session with EHL after using two probes and therefore were crossed over to LL, obtaining ductal clearance in a single additional session with a single LL fiber. EHL was significantly associated with a larger number of probes (2.0 vs. 1.02) to achieve ductal clearance (p < 0.01). The mean procedural time was significantly longer for EHL than for LL [72.1 (SD 16.3 min) versus 51.1 (SD 10.5 min)] (p < 0.01).

CONCLUSIONS

POC is highly effective for difficult biliary stones. Most patients achieved complete ductal clearance in one session, which was significantly more likely for stones < 22 mm. EHL was significantly associated with the need for more probes and a longer procedural time to achieve ductal clearance.

Initial clinical experience with the thulium fiber laser from Quanta System: First 50 reported cases

OBJECTIVE

To evaluate the new thulium fiber laser (TFL) from Quanta System (Fiber Dust™) in terms of efficiency, safety, and laser settings in laser lithotripsy during retrograde intrarenal surgery (RIRS).

METHODS

A prospective study of the first 50 patients with ureteral and renal stones who underwent RIRS using the new Fiber Dust (TFL from Quanta System, Italy) was performed in a single center. 200 µm and 150 µm laser fibers were used. Stone size, stone density, laser-on time (LOT) and laser settings were recorded. We also assessed the ablation speed (mm³/s), Joules/mm³ and laser power (W) values for each procedure.

RESULTS

A total of 50 patients were analyzed. The median (IQR) age was 54.5 (43-65) years old. Median (IQR) stone volume was 347 (147-1800) mm³ and 1125 (294-4000) mm³ for ureteral and renal stones, respectively. Median (IQR) stone density was 900 (400-1500) HU for ureteral stones and 950 (725-1125) HU for renal stones. Median (IQR) pulse energy was 0.6 (0.5-1) J and 0.6 (0.5-0.9) J for ureteral and renal stones, respectively. Median (IQR) frequency for ureteral stones was 10 (10-20) Hz and for renal stones, 15 (10-20) Hz. All procedures used short pulse. There were no statistically significant differences in pulse energy, frequency, laser power or LOT in both groups. The median (IQR) J/mm³ was 8.7 (4.8-65.2) for ureteral stones vs 14.3 (7.8-24.7) for renal stones. The median (IQR) ablation rate was 0.3 (0.2-1.3) mm³/s for ureteral stones vs 0.7 (0.4-1.2) mm³/s for renal stones. Neither of those results reached the significance threshold. Overall complication rate was low in both groups, and none was related to TFL.

CONCLUSION

According to our results, the new TFL laser is safe and effective for lithotripsy during RIRS, using low pulse energy and low pulse frequency.

In vitro fragmentation performance of a novel, pulsed Thulium solid-state laser compared to a Thulium fibre laser and standard Ho:YAG laser

The aim of this work was to compare the fragmentation efficiency of a novel, pulsed Thulium solid-state laser (p-Tm:YAG) to that of a chopped Thulium fibre laser (TFL) and a pulsed Holmium solid-state laser (Ho:YAG). During the fragmentation process, we used a silicone mould to fixate the hemispherical stone models under water in a jar filled with room-temperature water. Each laser device registered the total energy applied to the stone model to determine fragmentation efficiency. Our study examined laser settings with single pulse energies ranging from 0.6 to 6 J and pulse frequencies ranging from 5 to 15 Hz. Similar laser settings were applied to explicitly compare the fragmentation efficiency of all three devices. We experimented with additional laser settings to see which of the three devices would perform best. The fragmentation performance of the three laser devices differed statistically significantly (p < 0.05). The average total energy required to fragment the stone model was 345.96 J for Ho:YAG, 372.43 J for p-Tm:YAG and 483.90 J for TFL. To fragment the stone models, both Ho:YAG and p-Tm:YAG needed similar total energy (p = 0.97). TFL’s fragmentation efficiency is significantly lower than that of Ho:YAG and p-Tm:YAG. Furthermore, we found the novel p-Tm:YAG’s fragmentation efficiency to closely resemble that of Ho:YAG. The fragmentation efficiency is thought to be influenced by the pulse duration. TFL’s shortest possible pulse duration was considerably longer than that of Ho:YAG and p-Tm:YAG, resulting in Ho:YAG and p-Tm:YAG exhibiting better fragmenting efficiency.

New Lasers for Stone Treatment

Laser technology has been a breakthrough in urology. The new era in endocorporeal laser lithotripsy has recently begun in mid-2020, where promising technologies tested in vitro have reached their approval for clinical use and, in that way, have made it possible to confirm their safety and advantages in the real world, for the patient and for the urologist.

Prediction models of low-power holmium laser effectiveness in renal stone lithotripsy during retrograde intrarenal surgery

The objectives of this study are to develop prediction models for total laser energy (TLE) in order to infer surgical time and assist operative planning of intrarenal low-power Ho:YAG laser lithotripsy, and to predict the fragmented volume as well as the stone-free status (SFS). A retrospective review was performed, comprising all single surgeon standardized retrograde intrarenal surgery and low-power Ho:YAG laser lithotripsy at a tertiary care centre between October 2014 and September 2019. Automated measurement of stone volume and stone density (MSD), measured in Hounsfield units (HU), was employed in both pre- and post-operative non-contrast-enhanced computed tomography (NCCT), using a standardized technique on Osirix Lite® software. SFS was defined as complete absence of stone fragments, or fragments < 0.1 cm on meticulous inspection at the end of the procedure, and residual stone burden < 0.0005 cm³ on postoperative NCCT at 3 months. Statistical analysis was performed using the STATA® version 13.1 software for regression models. A p value < .05 was considered statistically significant. A total of 100 patients met the inclusion criteria, requiring a median of 22.3 kJ/cm³ (13.4-36.0) and resulting in a SFS of 41% at 3 months. In a multivariate analysis, according to stone composition, predicted TLE is equal: for uric acid (UA), 11.17 × volume(cm³) + 0.17 × MSD(HU) + 7.48 kJ; for mixed stones, 11.17 × volume(cm³) + 0.17 × MSD(HU) + 6.26 kJ; for calcium oxalate monohydrate (CaOM) stones, 11.17 × volume(cm³) + 0.17 × MSD(HU) + 1.14 kJ; and for calcium phosphate (CaPh) stones 11.17 × volume(cm³) + 0.17 × MSD(HU) - 1.94 kJ. Predicted fragmented volume is equal to 0.93 × volume(cm³) cm³. The significant predictors for SFS were UA stones, the presence of multiple stones, and lower TLE. In clinical practice, our models for intrarenal low-power Ho:YAG laser lithotripsy indicate that larger, denser, and UA stones are associated to higher TLE, and that single and UA stones are more commonly associated to SFS. Since higher TLE means longer operative time, when adjusting for laser parameters, our prediction models may help urologists plan surgeries more precisely based on stone characteristics, ultimately optimizing patients' treatment.

Ultrasound guided dual tract supine PCNL with simultaneous use of two different energy sources by two urologists working in unison-an innovative approach in staghorn calculus

Complete staghorn renal calculi are surgical challenge requiring multi-tract or staged PCNL. We report a case of supine PCNL where complete stone clearance was achieved with dual tracts (24 Fr/lower pole and 16Fr/upper pole) through which two surgeons operated simultaneously using two different energy sources (pneumatic/ultrasound lithotripter through 24Fr and Thulium Fiber laser through 16Fr). Strong water currents generated by dual-tract irrigation augmented the mini-PCNL venturi effect facilitating stone fragment evacuation. This is first reported case of two surgeons operating simultaneously using two different energy sources, in supine position in a limited space on a complete staghorn stone.

Radiation-free digital cholangioscopy-guided laser lithotripsy for large common bile duct stones: feasibility and technical notes

AIMS

Although endoscopic retrograde cholangiopancreatography (ERCP) for large common bile duct (CBD) stones is facilitated by digital cholangioscopy-guided lithotripsy, it is performed by fluoroscopy guidance. Here, we report our experience of non-radiation ERCP for large CBD stones using digital cholangioscopy-guided laser lithotripsy.

METHODS

Sixteen patients with large CBD stones underwent non-radiation digital cholangioscopy-guided laser lithotripsy and lithotomy. Data relevant to procedure details, adverse events, and short-term follow-up were analyzed.

RESULTS

Biliary access was achieved in all patients using standard guidewire-assisted cannulation, double-guidewire technique, and transpancreatic precut in twelve, two, and two patients, respectively. Balloons of 10 mm, 8 mm, and 6 mm in diameter were applied for EPBD in 8, 2, and 6 patients, respectively. Complete stone removal in one session was achieved in all patients. One round of laser lithotripsy was needed for stone ≤ 25 mm, and three-to-five rounds were needed for stones > 25 mm or multiple stones. One or two clips were used for endoscopic clipping. The time lengths of biliary access, digital cholangioscopy-assisted laser lithotripsy and stone extraction, and whole procedure were 3.5 ± 3.2 (0.5-12) minutes, 52.5 ± 30.6 (45-97) minutes, and 76 ± 23.3 (58-106) minutes, respectively. Asymptomatic hyperleukocytose, hyperamylasemia, and mild pancreatitis were present in 1, 2, and 1 patient(s), respectively. No other complications occurred. No cholangitis or recurrent CBD stones were observed.

CONCLUSION

Non-radiation digital cholangioscopy-guided laser lithotripsy is technically feasible and can be safely performed for endoscopic management of large CBD stones.

Comparison of scoring systems for predicting stone-free status and complications after retrograde ıntrarenal surgery

PURPOSE

To compare the effectiveness of scoring systems in predicting stone-free rates (SFR) and complications following retrograde intrarenal surgery (RIRS).

MATERIALS AND METHODS

We retrospectively analyzed 280 patients who underwent RIRS for kidney stones between 2016 and 2019. The Resorlu-Unsal Stone score (RUSS), Modified Seoul National University Renal Stone Complexity (S-ReSC) score, and R.I.R.S. scoring system score were calculated for each patient who was enrolled in the study. Subsequently, stone scoring systems were compared as to their predictive capability for SFR using receiver-operating characteristic curves. Furthermore, multivariate analysis was done to determine whether the scoring systems associated with SFR and complications.

RESULTS

The median patient age was 44 (35--56). The median RUSS, S-ReSC, and R.I.R.S scores were 0 (0-1), 1(1-2), and 6 (5-7), respectively. The overall SFR was 76.7%. The R.I.R.S. scoring system was found to have a higher predictive value in predicting postoperative SFR than the other two scoring systems (p < 0.001, AUC = 0,816). RUSS, R.I.R.S. score, and stone size were found to be independent predictive factors for SFR (p = 0.049, p = 0.024, p = 0.033, respectively). Complications were observed in 3.2%(9/280) of patients. Stone scoring systems were not statistically associated with complications. Operation duration was the only independent risk factor for complications (p = 0.010).

CONCLUSIONS

The R.I.R.S. scoring system was found to have a higher predictive value than RUSS and S-ReSC to predict SFR following RIRS in our study. However, none of the stone scoring systems was directly proportional to complications of RIRS.

Efficacy and safety of cholangioscopy guided laser lithotripsy for difficult bile duct stones - A prospective study from a tertiary care centre in Eastern India

BACKGROUND AND STUDY AIMS

Endoscopic sphincterotomy combined with endoscopic papillary balloon dilatation, mechanical lithotripsy or both, are effective modalities for the ex- traction of difficult common bile duct (CBD) stones. However, approximately 5-15% of cases are still difficult to treat. In the present study, we have evaluated the safety and efficacy of single- operator cholangioscopy guided laser lithotripsy (LL) for difficult to treat CBD stones.

PATIENTS AND METHODS

Consecutive patients undergoing LL for the extraction of difficult CBD stones were enrolled in the study. The primary outcomes were related to the efficacy of the procedure in terms of ductal clearance and safety in terms of complications.

RESULTS

During the 36 months, 764 patients presented for biliary stone extraction. Most of the patients, 683 (89.4%), had a successful stone extraction with standard techniques. Thirteen patients (1.7%) were not suitable for endoscopic therapy or did not consent for endoscopic therapy, and were referred directly for surgical treatment. Sixty-seven patients (8.8%) were included in the study. Cholangioscope was able to reach the stone in all the cases but one. Complete ductal clearance was achieved in 61 (91%) patients. Complications were encountered in 8 (11.9%) patients. All patients were asymptomatic at one-month of follow-up.

CONCLUSION

LL is a highly effective and safe procedure with minimal and transient complications.

Impact of Multiparametric Stone Measurement in Noncontrast Computer Tomography on Ureterorenoscopic Stone Removal

PURPOSE

Low-dose computer tomography (NCCT) is the standard imaging modality for patients with acute flank pain with a suspicion of urolithiasis. The stone size is usually measured 2D by a radiologist. We compared 3D stone measurement using different windows to the 2D measurement and evaluated the clinical impact on ureterorenoscopic stone removal (URS).

METHODS

One hundred sixty-four patients (201 stones) with a preoperative NCCT, following a URS within 4 weeks, were included in this study. Stone location, number and size of stones, operating time, and laser lithotripsy were documented. Stones were measured in 3D using bone and soft tissue window. The maximum diameter was compared to the radiological report. The U test, Kruskal-Wallis, and regression were used for statistical analyses.

RESULTS

Almost two-thirds (64.68%; 130 stones) of stone measurements in 3D with the bone window were lower than the radiologist reports in 2D. One-third (34.83%; 70 stones) of stone measurements were higher and 0.5% (1 stone) reported the same size. Using the 3D soft tissue window, 81.09% (163 stones), 17.91% (37 stones), and 1% (2 stones) of stones were measured bigger, smaller, or had the same measurement results, respectively. In the clinical setting, we could calculate a cutoff for laser lithotripsy at a maximum stone diameter of 5.70 mm (p < 0.01) with the 3D and 6.01 mm with the 2D measurements, respectively, and found a significant correlation between maximum stone diameter and operating time (p < 0.01) and number of stones and operating time (p < 0.01 with and p = 0.02 without laser).

CONCLUSION

3D stone measurement with bone window seems to be more accurate than 2D measurement, but 2D is sufficient for planning stone treatment.

Factors predicting duration and success of semirigid ureteroscopy for ureteral stones in different localizations

OBJECTIVE

In this study, we aimed to determine the factors predicting the duration and successof semirigid ureteroscopy performed for the treatment of ureteral stones in different localizations. MATERIALS AND METHODS: Medical records of the patients whom under went semirigid ureteroscopy for urolithiasis in our centre between January 2015 and December 2019 were retrospectively reviewed. The study group composed of 170 patients and divided into three subgroups; of which 54 in proximal ureter (31.8%), 51 in the mid (30 %) and 65 (38.2%) in the distal ureter. Predictive factors of semirigid ureteroscopy duration and success were determined by performance of correlation analysis and multivariate analysis.

RESULTS

Overall stone-free rate was calculated as 78.8%. Success rates for proximal, mid and distal ureteral stones were 72.2% (39/54 patients), 74.5% (38/51 patients) and 87.7% (57/65 patients), respectively. Complications were present in 19 patients (11.2%). Multivariate analysis indicated that stone diameter and stone burden independently affected the stone-free rate. Statistically significant negative correlation was determined between success of the procedure and stone diameter, stone burden, impaction and more proximal stone localization. While there was a statistically significant positive correlation between duration of procedure and stone burden, diameter, impaction, historyof ipsilateral ureteroscopy and more proximal stone localization, there was negative correlation between duration of procedure and stone-free status. CONCLUSION: We conclude that stone diameter, stone burden, impaction and more proximal stone localization are common factors affecting both duration and success of semirigid ureteroscopy. In addition, stone size and stone burden were determined as independent markers of stone-free status.

Cracking Difficult Biliary Stones

Apart from difficult biliary cannulation, biliary stone removal is considered one of the hurdles in endoscopic retrograde cholangiopancreatography. Generally, simple common bile duct (CBD) stones can be removed either with an extraction balloon or a basket. However, there are difficult stones that cannot be removed using these standard methods. The most difficult stones are large CBD stones and impacted stones in a tapering CBD. A few decades ago, mechanical lithotripsy was usually required to manage these stones. At present, endoscopic papillary large balloon dilation (EPLBD) of the biliary orifice has become the gold standard for large CBD stones up to 1.5 cm. EPLBD can reduce the procedural time by shortening the stone removal process. It can also save the cost of the devices, especially multiple baskets, used in mechanical lithotripsy. Unfortunately, very large CBD stones, stones impacted in a tapering CBD, and some intrahepatic duct stones still require lithotripsy. Peroral cholangioscopy provides direct visualization of the stone, which helps the endoscopist perform a probe-based lithotripsy either with an electrohydraulic probe or a laser probe. This technique can facilitate the management of difficult CBD stones with a high success rate and save procedural time without significant technical complications.

Histogram of kidney stones on non-contrast computed tomography to predict successful stone dusting during retrograde intrarenal surgery

PURPOSE

To predict successful dusting of kidney stones during retrograde intrarenal surgery (RIRS) using stone density parameters and histograms measured with non-contrast computed tomography imaging.

METHODS

Medical records of 49 patients who underwent retrograde intrarenal surgery between January 2018 and January 2019 at Kyung Hee University Hospital were reviewed, and the data of 55 stones were evaluated. Patient age, sex, mean stone density, the highest and lowest measured Hounsfield unit (HU), standard deviation and range of the measured HUs, volume of the most measured HU, and success of dusting were evaluated. Histograms of the measured HUs were created and cutoff values for successful dusting were analyzed.

RESULTS

Thirty-two stones were successfully dusted during surgery. Dusted stones had a wider range of HU and higher standard deviation. The volume of the most measured HU was smaller in the dusted stones. Successful dusting could be predicted when the volume of the most measured HU was < 8.9 mm³, with range ≥ 853, or when the volume of the most measured HU was < 8.9 mm³, with range < 853, and the mean stone density was < 355. The histograms of HUs of the dusted stones were wide and rugged, while those of dusting failed stones were narrow and peaked.

CONCLUSION

Evaluation of stone HU histograms showed differences in distribution and proportion. This will help predict surgical outcomes and prepare for intraoperative complications.

A case of fatal embolization during laser lithotripsy

PURPOSE

To report in literature the first case of fatal multi-organ embolization of ureteral stones fragments during laser lithotripsy.

CASE PRESENTATION

A tetraplegic 43-year-old woman was admitted to the hospital to undergo laser lithotripsy because of bilateral ureteral stones and right ureteral infected stent. During the removal of the right ureteral stent, the patient developed a sudden severe bradycardia followed by a reduction in the arterial oxygen saturation. In spite of a rapid and intensive medical intervention, the clinical picture did not improve; the woman was therefore transferred to the nearest Emergency Room where she was rescued but a cardiocirculatory arrest occurred. A claim of alleged medical malpractice was brought against the urologists. A complete autopsy was performed 8 days after death.

AUTOPSY FINDINGS

The diagnosis was determined by the microscopic findings: they have unequivocally shown a massive embolization of calculus fragments in the lungs and in the heart. In the light of all these findings, the cause of death was attributable to a disseminated intravascular coagulation due to this unforeseeable embolization of calcified amorphous material.

CONCLUSION

Embolization of calculus fragments represents an important challenge because it is extremely unpredictable. Indeed, a prompt diagnosis of non-thrombotic pulmonary embolism, during the urologic procedure, is extremely difficult because the condition presents with no specific clinical signs: this life-threatening pathology is often underestimated. For this reason, the autopsy and the subsequent histopathological examination are indispensable in order to prove lethal embolization: microscopic findings play a key role in the final diagnosis of death.

How does pre-operative antimicrobial treatment influence the intra-operative culture results and infectious complications in patients with positive baseline bladder urine culture undergoing ureteroscopic lithotripsy?

We investigated how pre-operative antimicrobial treatment influenced intra-operative culture (IC) results and infectious complications in patients with positive pre-operative bladder urine culture (PBUC) undergoing ureteroscopic lithotripsy. We assessed 162 patients undergoing ureteroscopic lithotripsy from April 2019 to March 2020. Based on PBUC findings, they were divided into positive and negative PBUC groups. We administered pre-operative antimicrobial treatment to the positive PBUC group and only peri-operative antimicrobial prophylaxis to the negative PBUC group. We examined intra-operative cultures (ICs), including bladder urine culture, renal pelvic urine culture and stone culture, in all cases. We studied the association between the results of PBUC, ICs and infectious complications in both groups. A total of 67 and 95 patients had positive and negative PBUC, respectively. In the positive PBUC group, 19 (28.4%) patients still had positive bladder urine culture after the antibiotic treatment. Positive ICs (43.3% vs. 3.2%, p < 0.001) and post-operative fever (16.4% vs. 2.0%, p = 0.001) were more common in the positive PBUC group than in the negative PBUC group. In the positive PBUC group, 11 patients had a post-operative fever, regardless of the ICs results (6 positive ICs and 5 negative ICs). Furthermore, antimicrobial-resistant bacteria were detected from ICs in 5 patients with positive PBUC, including 4 suffering from a post-operative fever. Although the effect of pre-operative antimicrobial treatment is not definitive, to avoid serious infectious complications, we should recognize high-risk patients and perform more careful infection control based on the pre- and intra-operative culture results.

Comparison of mean operative time in patients undergoing Ho: YAG laser lithotripsy and pneumatic lithotripsy in ureterorenoscopy for ureteric calculus

Objective

To compare the mean operative time (MOT) in patients undergoing Ho: YAG laser lithotripsy (LL) and pneumatic lithotripsy (PL) for ureteric stones.

Methods

This randomized study was conducted at Armed Forces Institute of Urology (AFIU) Rawalpindi, Pakistan from July 2016 to November 2018. Non probability consecutive sampling technique utilized to enroll 60 patients of both gender aged 18-60 years, having ureteric calculus ≤1.5cm. Randomization was done into group I (LL) and II (PL) via computer generated number tables. Six Consultant Urologists performed surgeries under spinal anesthesia utilizing Swiss Lithoclast^® Master (EMS⁺ S.A. Switzerland) in group II and holmium laser fiber (365μm, 8-10Hz, 9.6-16W, 2100nm wavelength) in group I respectively. MOT was noted from insertion of cystoscope till removal out of meatus. Data obtained was analyzed through IBM SPSS 24.0.

Results

Analysis involved 60 patients (30 each group) having similar baseline characteristics (age, gender, laterality, location). There was statistically significant different MOT between LL & PL (25.48±6.99 vs 34.83± 7.47 minutes, p < 0.001). Data stratification with respect to age, gender, laterality and stone location revealed similar trend. Lithotripsy technique significantly affected MOT (p < 0.001) on Multiple Linear Regression Analysis.

Conclusions

Ho: YAG LL is an efficient technique when compared with PL in terms of MOT for ureteric stones.

Therapeutic ureteroscopy for urolithiasis in children younger than 60 months of age

PURPOSE

The management of urinary tract calculi has evolved dramatically in children with the development of smaller and more durable endoscopic equipment. The indications for therapeutic ureteroscopy in children have significantly expanded with the availability of smaller caliber endoscopes and Holmium:YAG laser. In this paper, we review our experience of the management of urolithiasis and report outcomes of therapeutic ureterorenoscopy (URS) in children younger than 60 months.

METHODS

We retrospectively reviewed the inpatient, outpatient records, and imaging data of our hospital, of all children ≤ 60 months of age undergoing URS for the treatment of urinary stones.

RESULTS

During the study period; 77 children, mostly male (70.1%) presenting with a single calculus and a mean age of 28.97 ± 2.44 months underwent therapeutic URS. A majority of children (71.4%) had lower or mid-ureteric calculi. Pre URS double J (DJ) stenting was necessary for 21 (27.2%) children. A total of 24 (31.1%) children needed ureteric dilatation before the ureteroscopy. Post URS DJ stenting was necessary in 41 (53.2%) children. Stents were retrieved within 10 days of the procedure. Stone clearance rate following a single-stage URS procedure was 94.8%, and 4 (5.2%) children needed additional shockwave lithotripsy (SWL) to achieve stone clearance. Overall complication rate including hematuria and fever was 12.9% (10 patients).

CONCLUSION

Therapeutic ureterorenoscopy in the management of ureteric and selective renal pelvic calculi is safe and effective. It can be considered as the first-line therapy in young children.

Evaluation of a new disposable flexible ureterorenoscope and comparison to an established disposable flexible ureterorenoscope: a prospective, observational study

PURPOSE

To objectively and subjectively assess the performance and surgical outcomes of the new Innovex EU-scope™ single-use digital flexible ureteroscope (fURS).

METHODS

A prospective cohort study was carried out (August 2019 to May 2020). The new single-use fURS (Innovex Medical Devices Co. Shanghai, China) was analysed with regard to visibility, manoeuvrability, laser interference and overall performance using a validated Likert scale. Outcomes are compared to the LithoVue™ (Boston Scientific, Marlborough, MA).

RESULTS

One hundred patients were included in this study. 50 cases underwent retrograde fURS using the Innovex EU-scope™ and 50 with the LithoVue™. There were no differences in the patient demographics data, or operative data between the two groups. The Innovex EU-scope™ scored higher visibility scores compared to the LithoVue™, median 4, interquartile range (IQR) (4-4), vs. 3.5, IQR (3-5), p = 0.5086. Both scopes had similar manoeuvrability scores. The Innovex EU-scope™ scored significantly lower with regard to comfort compared to the LithoVue, median 4 IQR (3-4) vs. 4.5 IQR (4-5), p = 0.0445. Whereas, laser interference, affected the Innovex much less than the LithoVue™. Both scopes scored well for overall performance. The median overall performance score for the Innovex was 4 IQR (4-4) vs. 4 IQR (4-5).

CONCLUSIONS

This Innovex EU-scope™ has good objective and subjective visibility and manoeuvrability profiles. This single-use flexible ureteroscope may achieve similar clinical outcomes to an established single use instrument.

[Innovative laser technologies in the treatment of urolithiasis : A change to more gentle methods with increased patient safety]

Management of urolithiasis has undergone fundamental changes with the introduction of extracorporeal shock wave lithotripsy (ESWL) and percutaneous and ureterorenoscopic techniques in the 1980s. Since then, these minimally invasive techniques have been continuously optimized and specific laser techniques for stone disintegration have emerged. Besides the established holmium laser, other types of lasers are also emerging. Especially the thulium fiber laser is the subject of promising research due to its variable adjustment options. In terms of patient safety, both holmium and thulium techniques seem to be similar . While serious direct physical lesions are rare, there is increasing evidence of clinically relevant secondary thermal injury due to increased temperatures in the upper urinary tract during treatment. Our research group has recently demonstrated in both in vitro and in vivo (porcine animal model) experiments that monitoring the fluorescence spectra of calculi allows precise target differentiation between stone, tissue, and endoscope components. Consequently, pulse emissions were only emitted when stone material was detected. We believe that target monitoring will minimize the risk of laser-induced urothelial damage and decrease energy release into the upper urinary tract allowing adequate temperature management.

Bouveret syndrome masquerading as a gastric mass-unmasked with endoscopic luminal laser lithotripsy: A case report

BACKGROUND

Bouveret syndrome, also known as gallstone ileus, is a rare form of gastric outlet obstruction accounting for 1%-3% of cases. This condition is most often reported in females. The diagnosis can be challenging and is often missed due to atypical presentations, which occasionally mimic gastric outlet obstruction symptoms such as nausea, vomiting, loss of appetite and hematemesis. The symptoms vary with stone size. Larger stones are managed with a surgical approach, but this carries increased morbidity and mortality. Over the past decade, the endoscopic approach has emerged as an alternative mode of treatment, but it is generally unsuccessful in the management of larger-sized stones. A literature review revealed cases of successful endoscopic treatment requiring multiple sessions for stone sizes measuring up to about 4.5 cm. Here we present a unique case of an elderly patient with Bouveret syndrome with a 5 cm stone mimicking a gastric mass and causing gastric outlet obstruction, who was successfully managed in a single session using a complete endoscopic approach with laser lithotripsy.

CASE SUMMARY

An 85-year-old female patient presented with 1-month history of intermittent abdominal pain, vomiting, decreased appetite and weight loss. An abdominal computed tomography showed a 4.5 cm × 4.7 cm partially calcified mass at the gastric pylorus causing gastric outlet obstruction. Endoscopy showed an ulcerated fistulous opening and a large 5 cm impacted gallstone in the duodenal bulb. Endoscopic nets and baskets were used in an attempt to remove the stone, but this approach was unsuccessful. Given her advanced age, poor physical condition and underlying comorbidities, she was deemed to be high-risk for surgery. Thus, a minimally invasive approach using endoscopic laser lithotripsy was attempted and successfully treated the stone. Post-procedure, the patient experienced complete resolution of her symptoms with no complications and was able to tolerate her diet. She was subsequently discharged home at 48 h, with an uneventful recovery.

CONCLUSION

In our paper we describe Bouveret syndrome and highlight its management with a novel endoscopic approach of laser lithotripsy in addition to various other endoscopic approaches available to date and its success rates.

Laser lithotripsy for proximal ureteral calculi in adults: can 3D CT texture analysis help predict treatment success?

OBJECTIVE

To explore whether multiple 3D computed tomography texture analysis (3D-CTTA) parameters can predict the therapeutic effects of holmium: YAG laser lithotripsy (LL) on ureteral calculi.

METHODS

The files from 94 patients (102 stones) with proximal ureteral calculi treated only by LL at a single institution were retrospectively retrieved from January 2016 to March 2019. According to intra-operative observations and postoperative reexamination, samples were divided into a completely crushed and a non-crushed group. Preoperative non-contrast-enhanced computed tomography (NCCT) images obtained by multiple CT scanners were imported to MaZda software for 3D texture analysis (TA). The CT-derived value of each target stone was measured, and 15 TA parameters were extracted by delineating volumes of interest (VOIs). Receiver operating characteristic (ROC) curves were drawn to determine the optimal critical value of each parameter based on the Youden index, and univariable and multivariable logistic regression analyses determined the significant factors for LL success.

RESULTS

In univariable analysis, significant differences (p < 0.05) were observed among 7 parameters. In multivariable analysis, Perc.01 3D > 2062 (p = 0.03) and Z-fraction of image in runs (Z-Fraction) > 0.45570 (p = 0.009) were significant independent predictors, with odds ratios (ORs) of 24.204 and 60.329, respectively. In subgroup analysis based on the cutoff value of the CT-derived value (HU = 960), Perc.01 3D (OR = 44.154, 95% CI (2.379, 819.618), p = 0.011) and Z-Fraction (OR = 14.519, 95% CI (2.088, 100.953), p = 0.007) remained statistically significant.

CONCLUSIONS

The combination of 3D-CTTA parameters and the CT-derived value can be used as a quantitative reference to predict whether a target stone could be completely crushed by LL.

KEY POINTS

• Computed tomography texture analysis (CTTA) may be helpful in selecting suitable laser lithotripsy (LL) patients. • 3D-CTTA better predicts stone fragility than commonly used methods (such as the CT-derived value). • The combination of CTTA and the CT-derived value can be used as a preoperative quantitative reference.

Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy

Purpose

To summarize current knowledge on intracorporeal laser lithotripsy in flexible ureterorenoscopy (fURS), regarding basics of laser lithotripsy, technical aspects, stone clearance, lithotripsy strategies, laser technologies, endoscopes, and safety.

Methods

A scoping review approach was applied to search literature in PubMed, EMBASE, and Web of Science. Consensus was reached through discussions at the Consultation on Kidney Stones held in September 2019 in Copenhagen, Denmark.

Results and conclusions

Lasers are widely used for lithotripsy during fURS. The Holmium laser is still the predominant technology, and specific settings for dusting and fragmenting have evolved, which has expanded the role of fURS in stone management. Pulse modulation can increase stone ablation efficacy, possibly by minimizing stone retropulsion. Thulium fibre laser was recently introduced, and this technology may improve laser lithotripsy efficiency. Small fibres give better irrigation, accessibility, and efficiency. To achieve optimal results, laser settings should be adjusted for the individual stone. There is no consensus whether the fragmentation and basketing strategy is preferable to the dusting strategy for increasing stone-free rate. On the contrary, different stone scenarios call for different lithotripsy approaches. Furthermore, for large stone burdens, all laser settings and lithotripsy strategies must be applied to achieve optimal results. Technology for removing dust from the kidney should be in focus in future research and development. Safety concerns about fURS laser lithotripsy include high intrarenal pressures and temperatures, and measures to reduce both those aspects must be taken to avoid complications. Technology to control these parameters should be targeted in further studies.

Laser-guided real-time automatic target identification for endoscopic stone lithotripsy: a two-arm in vivo porcine comparison study

Introduction and objective

Thermal injuries associated with Holmium laser lithotripsy of the urinary tract are an underestimated problem in stone therapy. Surgical precision relies exclusively on visual target identification when applying laser energy for stone disintegration. This study evaluates a laser system that enables target identification automatically during bladder stone lithotripsy, URS, and PCNL in a porcine animal model.

Methods

Holmium laser lithotripsy was performed on two domestic pigs by an experienced endourology surgeon in vivo. Human stone fragments (4–6 mm) were inserted in both ureters, renal pelvises, and bladders. Ho:YAG laser lithotripsy was conducted as a two-arm comparison study, evaluating the target identification system against common lithotripsy. We assessed the ureters’ lesions according to PULS and the other locations descriptively. Post-mortem nephroureterectomy and cystectomy specimens were examined by a pathologist.

Results

The sufficient disintegration of stone samples was achieved in both setups. Endoscopic examination revealed numerous lesions in the urinary tract after the commercial Holmium laser system. The extent of lesions with the feedback system was semi-quantitatively and qualitatively lower. The energy applied was significantly less, with a mean reduction of more than 30% (URS 27.1%, PCNL 52.2%, bladder stone lithotripsy 17.1%). Pathology examination revealed only superficial lesions in both animals. There was no evidence of organ perforation in either study arm.

Conclusions

Our study provides proof-of-concept for a laser system enabling automatic real-time target identification during lithotripsy on human urinary stones. Further studies in humans are necessary, and to objectively quantify this new system’s advantages, investigations involving a large number of cases are mandatory.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03452-0) contains supplementary material, which is available to authorized users.

Efficacy of pancreatoscopy for pancreatic duct stones: A systematic review and meta-analysis

BACKGROUND

Pancreatic duct stones can lead to significant abdominal pain for patients. Per oral pancreatoscopy (POP)-guided intracorporal lithotripsy is being increasingly used for the management of main pancreatic duct calculi (PDC) in chronic pancreatitis. POP uses two techniques: Electrohydraulic lithotripsy (EHL) and laser lithotripsy (LL). Data on the safety and efficacy are limited for this procedure. We performed a systematic review and meta-analysis with a primary aim to calculate the pooled technical and clinical success rates of POP. The secondary aim was to assess pooled rates of technical success, clinical success for the two individual techniques, and adverse event rates.

AIM

To perform a systematic review and meta-analysis of POP, EHL and LL for management of PDC in chronic pancreatitis.

METHODS

We conducted a comprehensive search of multiple electronic databases and conference proceedings including PubMed, EMBASE, Cochrane, Google Scholar and Web of Science databases (from 1999 to October 2019) to identify studies with patient age greater than 17 and any gender that reported on outcomes of POP, EHL and LL. The primary outcome assessed involved the pooled technical success and clinical success rate of POP. The secondary outcome included the pooled technical success and clinical success rate for EHL and LL. We also assessed the pooled rate of adverse events for POP, EHL and LL including a subgroup analysis for the rate of adverse event subtypes for POP: Hemorrhage, post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP), perforation, abdominal pain, fever and infections. Technical success was defined as the rate of clearing pancreatic duct stones and clinical success as the improvement in pain. Random-effects model was used for analysis. Heterogeneity between study-specific estimates was calculated using the Cochran Q statistical test and I² statistics. Publication bias was ascertained, qualitatively by visual inspection of funnel plot and quantitatively by the Egger test.

RESULTS

A total of 16 studies including 383 patients met the inclusion criteria. The technical success rate of POP was 76.4% (95%CI: 65.9-84.5; I² = 64%) and clinical success rate was 76.8% (95%CI: 65.2-85.4; I² = 66%). The technical success rate of EHL was 70.3% (95%CI: 57.8-80.3; I² = 36%) and clinical success rate of EHL was 66.5% (95%CI: 55.2-76.2; I² = 19%). The technical success rate of LL was 89.3% (95%CI: 70.5-96.7; I² = 70%) and clinical success rate of LL was 88.2% (95%CI: 66.4-96.6; I² = 77%). The incidence of pooled adverse events for POP was 14.9% (95%CI: 9.2-23.2; I² = 49%), for EHL was 11.2% (95%CI: 5.9-20.3; I² = 15%) and for LL was 13.1% (95%CI: 6.3-25.4; I² = 31%). Subgroup analysis of adverse events showed rates of PEP at 7% (95%CI: 3.5-13.6; I² = 38%), fever at 3.7% (95%CI: 2-6.9; I² = 0), abdominal pain at 4.7% (95%CI: 2.7-7.8; I² = 0), perforation at 4.3% (95%CI: 2.1-8.4; I² = 0), hemorrhage at 3.4% (95%CI: 1.7-6.6; I² = 0) and no mortality. There was evidence of publication bias based on funnel plot analysis and Egger’s test.

CONCLUSION

Our study highlights the high technical and clinical success rates for POP, EHL and LL. POP-guided lithotripsy could be a viable option for management of chronic pancreatitis with PDC.

SpyGlass-guided laser lithotripsy versus laparoscopic common bile duct exploration for large common bile duct stones: a non-inferiority trial

BACKGROUND

Laparoscopic common bile duct exploration (LCBDE) is the first choice of treatment for large common bile duct (CBD) stones. Recently, single-operator cholangioscopy (SpyGlass system) has been introduced widely in referral and large medical centers. Several studies have reported favorable results for treatment of large CBD stones guided by SpyGlass. We evaluated the clinical efficacy and safety of SpyGlass-guided laser lithotripsy LCBDE for treatment of large CBD stones.

METHODS

From August 2015 to August 2018, 157 patients with large bile duct stones who met the inclusion criteria were randomly divided into two groups: SpyGlass-guided laser lithotripsy (Group A) and LCBDE (Group B). The efficacy and complications were compared between the groups.

RESULTS

Although the first-session stone removal rate in Group A was significantly lower than that in Group B, Group A was not inferior to Group B in terms of total stone removal rate. Compared with Group B, Group A had shorter hospital stay and enhanced recovery. The short-term complication rates were also similar between the two groups.

CONCLUSIONS

The clinical efficacy of SpyGlass-guided laser lithotripsy for the treatment of large CBD stones is not inferior to that of LCBDE, and it is less invasive. SpyGlass-guided laser lithotripsy is an important option for treatment of large CBD stones.

Direct Comparison of Pneumatic and Ho:YAG Laser Lithotripsy in the Management of Lower Ureteric Stones

INTRODUCTION

Besides extracorporeal shockwave lithotripsy, semi-rigid ureteroscopy (URS) has become an equal therapy of choice for the treatment of most distal ureteric stones. Before the wide availability of laser lithotripsy as a tool for stone fragmentation, pneumatic lithotripsy was, and still is, widely used. In a country like Iraq, availability and affordability are the huge questions asked. Besides the capital investment for a laser machine, the pneumatic device is reusable, whereas the laser fibers are limited in their reusability. This makes pneumatic lithotripsy a more cost-effective option, at least in our setting. The question remains whether both options, compared in our setting with our limited resources, are equally effective and beneficial to our patients.

PATIENTS AND METHODS

Fifty patients were included in our prospective study who underwent URS for the treatment of a distal ureteric stone. Half each (n = 25) underwent pneumatic (group A) or laser lithotripsy (group B). Inclusion criteria were a single distal ureteric stone measuring 7-20 mm in largest diameter, no anatomical abnormality, age >18 years, and an unsuccessful attempt of medical expulsion therapy. Patients with signs of urinary infection and pregnant women were excluded. All patients were operated upon under spinal anesthesia. Data recorded included operation time, stone size, type of scope and lithotripter, complications, hospital stay, and stone-free rate.

RESULTS

Both groups did not show statistically significant differences in patient demography, stone size, operation time, complications, and stone-free rates (p > 0.05).

CONCLUSION

Both pneumatic and Ho:YAG laser lithotripsy are equally effective and safe in treating distal ureteric stones in our setting. If the cost and availability of laser treatment is an issue, pneumatic lithotripsy is a viable and more cost-effective option.

Characterization of intracalyceal pressure during ureteroscopy

PURPOSE

To provide the first report of measuring intracalyceal pressures during ureteroscopy (URS).

METHODS

A prospective single-center clinical study using a cardiac pressure guidewire to measure intracalyceal pressure during flexible URS was performed. Eight patients (45 calyces) undergoing URS for nephrolithiasis were included. A Verrata^® pressure guide wire was passed through the working channel of a dual lumen flexible ureteroscope and into the calyces while irrigation was maintained at 150 mmHg. Pressure was measured in the renal pelvis, upper pole, interpolar, and lower pole calyces both with and without a ureteral access sheath (UAS). The pressure in each location with and without a UAS was compared. The correlation between calyceal pressure and infundibular dimensions (width, length) was determined.

RESULTS

Intracalyceal pressure was significantly lower in each region when a UAS was used. Compared to patients with a 12/14Fr UAS, those with a 14/16Fr UAS had significantly lower pressure in the interpolar (25.3 ± 13.1 vs. 44.0 ± 27.5 mmHg, p = 0.03) and lower pole (16.2 ± 3.5 vs. 49.2 ± 40.3 mmHg, p = 0.004) calyces. Interpolar calyceal pressure in the presence of a UAS was significantly higher than the renal pelvis pressure (RPP) (30.8 ± 19.6 vs. 17.9 ± 11.0 mmHg, p = 0.004).

CONCLUSIONS

During flexible URS, RPP strongly correlates with, but does not uniformly represent, the intracalyceal pressure. With a 14/16Fr UAS and an inflow pressure of 150 mmHg, RPP and intracalyceal pressure never exceed the threshold for renal backflow.

Successful endoscopic treatment of a large impacted gallstone in the duodenum using laser lithotripsy, Bouveret’s syndrome: A case report

BACKGROUND

Bouveret´s syndrome is defined as a gastric outlet obstruction after passage of a gallstone through a fistula into the duodenum. Due to its rarity, the diagnosis of Bouveret’s syndrome is often delayed and causes a high morbidity and mortality rate.

CASE SUMMARY

A 93-year-old female presented with worsening pain in the right upper abdomen and vomiting. A gastroscopy revealed fluid retention caused by a massive obstructive stone in the bulbus. Endoscopic laser lithotripsy of the impacted stone was planned after multidisciplinary consultation. A Dornier Medilas H Solvo lithotripsy 350 µm laser fiber (10 Hz, 2 Joules) was used to disintegrate the stone into smaller pieces. The patient recovered completely.

CONCLUSION

A mechanical obstruction due to a gallstone that has entered the gastrointestinal tract is a complication that appears in 0.3%-0.5% of patients who have cholelithiasis. Stones larger than 2 cm can become impacted in the digestive tract, which occurs mostly in the terminal ileum. In approximately 1%-3% of cases, the stones cause obstruction in the duodenum. This phenomenon is called Bouveret’s syndrome. As this condition is mostly observed in elderly individuals with multiple comorbidities, treatment by an open surgical approach is unsuitable. Endoscopic removal is the preferred technique. The benefit of using laser lithotripsy is the precise targeting of energy onto the stone with minimal tissue injury. Endoscopic laser lithotripsy is a safe and feasible treatment option for Bouveret’s syndrome.

What is the exact definition of stone dust? An in vitro evaluation

PURPOSE

To propose a size-related definition of stone dust produced by lithotripsy of urinary stones.

METHODS

Stone dust was defined as particles small enough to adhere to the following criteria: (1) spontaneous floating under 40 cm H₂O irrigation pressure; (2) mean sedimentation time of > 2 s through 10 cm saline solution; (3) fully suitable for aspiration through a 3.6 F working channel. Irrigation, sedimentation, and aspiration tests were set up to evaluate each criterion. Primary outcome was particle size limit agreeing with all three criteria. Stone particles with a given size limit (≤ 2 mm, ≤ 1 mm, ≤ 500 µm, ≤ 250 µm, ≤ 125 µm and ≤ 63 µm) were obtained from laser lithotripsy, including samples from prevailing stone types: calcium oxalate monohydrate, calcium oxalate dihydrate, uric acid, carbapatite, struvite, brushite, and cystine.

RESULTS

All particles ≤ 250 µm from all stone types were in agreement with all three criteria defining stone dust, except for struvite where size limit for a positive irrigation and sedimentation test was ≤ 125 µm.

CONCLUSION

A size limit of ≤ 250 µm seems to generally adhere to our definition of stone dust, which is based on floating and sedimentation proprieties of stone particles, as well as on the ability to be fully aspirated through the working channel of a flexible ureteroscope.