Does the renal parenchymal thickness affect the efficacy of the retrograde intrarenal surgery? A prospective cohort study

A Novel Hydrodynamic Design Greatly Improves the Debris Clearance Rate of Flexible Ureteroscopy

Objectives: To introduce a novel hydrodynamic design for a flexible ureteroscope that can increase stone debris clearance. Methods: Based on hydrodynamics, the new design allowed the ureteroscope to have six water jets. Fluid gushed from the six jets and would ultimately converge into an eddy. The safety and stone debris clearance efficiency were tested in a 3D-printed kidney model. Stone fragments between 0.5 and 1 mm were used to mimic the debris. A ureteroscope already approved for marketing was used as a control. Results: The new design did not change the local renal pressure and did not raise the whole renal pressure under irrigation at 80 or 100 mL/min but slightly raised it under irrigation at 120 mL/min. The pressures in the 2 g stone clearance procedures were 26.0, 33.1, and 37.5 cmH2O for the new design and 25.1, 30.2, and 39.3 cmH2O for the current design; in the 4 g stone clearance procedures, the pressures were 30.1, 37.2, and 40.0 cmH2O for the new design and 26.9, 30.8, and 39.8 cmH2O for the current design, all under conditions of 80, 100, and 120 mL/min irrigation, respectively. The new design significantly improved the stone clearance rate by ∼10-fold. It effectively cleared 2 and 4 g stones within 900 seconds under the three irrigation rates. In contrast, the current design cleared <10% of the stone debris in all tests. Conclusion: The new hydrodynamic design significantly improved the stone debris clearance rate without causing obviously increased renal pressure, and the improvement was maintained under different irrigation pressures and stone burdens.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery

OBJECTIVES

To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS.

MATERIALS AND METHODS

After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided.

RESULTS

A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications.

CONCLUSION

The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.

Can additional variables be used to predict stone-free rates following retrograde intrarenal surgery? Anticoagulants and parenchyma thickness: a detailed examination

The purpose of this article is to identify the factors that predict the success of retrograde intrarenal surgery (RIRS), with a focus on the effect of renal parenchymal thickness and anticoagulant use on stone-free rates. From February 2014 to April 2022, cases of kidney stones treated with RIRS at our clinic were retrospectively screened. The study included 642 cases meeting all inclusion and exclusion criteria. The patients who were observed to be stone free after a single session of RIRS were assigned to Group F, while those with residual fragments were assigned to Group R. Group F comprised 472 patients, while Group R included 170 patients. The two groups have compared certain preoperative and postoperative laboratory and radiological parameters. The infundibulopelvic angle was significantly more acute in Group R (45.63 ± 16.25 vs. 49.28 ± 15.36, p = 0.011) while patients in Group F tended to have thicker parenchyma (27.39 ± 8.38 vs. 22.88 ± 5.56, p < 0.001). In our analysis of multivariate logistic regression, stone size (OR: 1.074, 1.037-1.113; p < 0.001), lower calyceal location (OR: 0.550, 95% CI 0.364-0.831; p = 0.005), multiple numbers of stones (OR 0.254, 95% CI 0.166-0.389; p =  < 0.001), the value of parenchymal thickness (OR 0.911, 95% CI 0.882-0.941; p =  < 0.001) and more importantly use of anticoagulants/antiplatelets (OR 0.557, 95% CI 0.333-0.933; p = 0.026) appeared to be independent predictors of stone-free status after RIRS. Further evaluation of the data revealed that the cut-off value of the renal parenchymal thickness for an effective stone-free status in a ROC curve analysis was 24.5 with 62.9% sensitivity and 56.8% specificity (area under curve value: 0.654 [95% CI 0.608-0.699, p < 0.001]). The endourologist may be able to make more informed decisions by evaluating renal parenchymal thickness in addition to patient-related factors like anticoagulant use, which we find significantly affects outcomes, along with the stone and renal anatomy-related factors.