Renal Stone Features Are More Important Than Renal Anatomy to Predict Shock Wave Lithotripsy Outcomes: Results from a Prospective Study with CT Follow-Up

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Development of a novel predictive model for a successful stone removal after flexible ureteroscopic lithotripsy based on ipsilateral renal function: a single-centre, retrospective cohort study in China

OBJECTIVES

The aims of this study were to investigate the effect of preoperative ipsilateral renal function on the success of kidney stone removal with flexible ureteroscopic lithotripsy and to develop a predictive model based on the results.

DESIGN

Retrospective cohort study.

SETTING

Data from the 2001-2012 period were collected from the electronic records of West China Hospital, Sichuan University.

PARTICIPANTS

576 patients who underwent flexible ureteroscopic lithotripsy were included in the study.

PRIMARY OUTCOME

Stone-free rate (SFR) after the procedures.

RESULTS

In patients with suspected impaired kidney function, the overall SFR was 70.1%. Stone volume (OR 1.46; 95% CI 1.18 to 1.80), lower calyx stones (OR 1.80; 95% CI 1.22 to 2.65), age (OR 1.02; 95% CI 1.00 to 1.04), body mass index (OR 1.10; 95% CI 1.04 to 1.17) and estimated glomerular filtration rate of the affected kidney (OR 0.95; 95% CI 0.94 to 0.97) were identified as independent predictors of SFR. Lasso regression selected the same five predictors as those identified by univariate and multivariate logistic regression analyses, thus verifying our model. The mean area under the curve, based on 1000 iterations and 10-fold validation, was 0.715 (95% CI 0.714 to 0.716). The Hodges-Lehmann test and calibration curve analysis revealed no significant mismatch between the prediction model and the retrospective cohort.

CONCLUSION

Ipsilateral renal function may be a novel independent risk factor for kidney stone removal with flexible ureteroscopic lithotripsy. A novel nomogram for predicting SFR that uses stone volume, lower calyx stones, age, body mass index and estimated glomerular filtration rate was developed, but remains to be externally validated.

Importance of precise imaging for stone identification during shockwave lithotripsy: a critical evaluation of "OptiVision" as a post-processing radiography imaging modality

To evaluate the efficacy of a unique imaging software "OptiVision" on the confidence of stone identification using X-ray imaging during shockwave lithotripsy. A total of 57 patients with solitary radio-opaque kidney stones sized < 15 mm were included and evaluated with appropriate radiological imaging and laboratory studies before undergoing shockwave lithotripsy (SWL). The size of the stones was measured on KUB and CT images using maximal stone diameters. All patients were evaluated with radiography on the Dornier Delta III immediately before SWL and at the end of the SWL session with fluoroscopy, a snapshot image, and the OptiVision modality (applied over the acquired snapshot image without additional radiation exposure) for precise identification of the stone. All images obtained with these three different imaging modalities (fluoroscopy, snapshot, and OptiVision) were comparatively evaluated for confidence levels in stone identification using a five-point Likert scale (1 = poor diagnostic confidence, 5 = excellent diagnostic confidence). These confidence levels were also used to differentiate between stones and bony structures using these same imaging modalities. Results were evaluated for statistical significance regarding their impact on the precise identification of renal stones. A total of 57 patients with solitary stones were evaluated using flouroscopy, snapshot, and OptiVision images before and after SWL to ascertain the efficacy of these 3 imaging modalities on the precise identification of the calculi. Stone sizes ranged from 4 to 15 mm, with a mean of 8.30 mm in the longest dimension. Evaluation of the findings demonstrated that while the pre- and post-SWL confidence of fluoroscopic stone identification was from 29.51 to 31.15%, the values using snapshot ranged from 31.15 to 39.34%. Pre- and post-SWL confidence of stone identification with OptiVision post-processing imaging was approximately 89%. In the majority of cases (n = 43), the use of OptiVision image processing enabled urologists to identify the stone with a higher level of confidence rating than the use of both fluoroscopy (n = 0) and snapshot (n = 0) image processing tools. While a rating level of 4 or higher was given in 89% of images obtained by OptiVision during the pre- and post-SWL phase, this value was only 37% (4 or more points) using fluoroscopy and Snapshot image processing techniques. For all the radiography image processing tools, the distribution of the Likert score differed significantly among the OptiVision, fluoroscopy, and snapshot imaging modalities (p < 0.001). Precise and reliable identification of stone(s) located in the kidney is essential in delivering shock waves to the desired focal point and achieving higher stone-free rates. Our findings demonstrated that using the specially designed imaging modality OptiVision was significantly helpful in identifying and localizing stones with high-quality images before SWL for effective stone disintegration during this procedure.

Residual Stone Fragments After Percutaneous Nephrolithotomy: Shockwave Lithotripsy vs Retrograde Intrarenal Surgery

Background: Despite technology incorporation to percutaneous nephrolithotomy (PCNL), residual stone fragments (RSFs) may still persist after PCNL and need to be addressed to avoid regrowth or ureteral obstruction. The objective of this study was to compare the outcomes of retrograde intrarenal surgery (RIRS) to extracorporeal shockwave lithotripsy (SWL) for treating patients with RSFs after a previous standard PCNL. Materials and Methods: Adult patients with RSF after a standard PCNL submitted to RIRS or SWL in our Institution from January 2017 to January 2020 were retrospectively studied. Stone-free rate (SFR) was evaluated on postoperative day (POD) 90 by noncontrast CT (NCCT) or ultrasound and kidney, ureter, and bladder radiograph (KUB) for each renal unit. Surgical complications based on Clavien-Dindo classification during the 90 days of follow-up were recorded. Sample size was calculated for a power of 80% and a significance level of 0.05, assuming SFR of 20% for SWL and 50% for RIRS. Results: Thirty-three patients treated by SWL were compared with 36 patients treated by RIRS. Hospitalization time was longer in the RIRS group (4.18 vs 12.33 hours, p = 0.001). SFR and success rate were lower in SWL than RIRS group (24.2% vs 58.3%, p = 0.007 and 30.3% vs 72.2%, p = 0.004, respectively), using POD 90 NCCT in 81.8% and ultrasound and KUB in 18.2% of the SWL group and using POD 90 NCCT in 100% of the RIRS group. Minor complications (Clavien-Dindo < III) occurred in 11 of 36 (30.6%) patients submitted to RIRS and in 2 of 33 (6.1%) patients submitted to SWL group (p = 0.025). Two patients (6.1%) of the SWL group had Clavien-Dindo IIIb complication owing to Steinstrasse and were submitted to ureteroscopy. Emergency room visits were similar between groups (6.1% vs 8.3%, p = 1.0). Conclusions: RIRS has better SFR, higher minor complications, and lower major complications than SWL for the treatment of RSFs after standard PCNL.

Prediction of stone-free rates following extracorporeal shockwave lithotripsy in a contemporary cohort of patients with stone densities exceeding 1000 HU

Purpose: Nephrolithiasis is a common urologic problem, and its incidence is increasing. Shockwave Lithotripsy (SWL) has better results for patients with stones < 1000 HU. We attempted to identify SWL stone-free (SF) predictors for > 1000 HU stones.Methods: From January 2013 to September 2019, patient shared decision consecutive SWL for the treatment of a single > 1000 HU renal stone diagnosed by non-contrast computed tomography (NCCT). Endpoints: Fragmentation and SF or clinically insignificant residual fragments ≤ 4 mm at 4 weeks. Age, gender, stone side, location, size and density, number and average energy (Joules) of shocks were explored on uni- and multivariate regression analysis.Results: All sixty-one patients included were diagnosed with renal stone between 5 and 20 mm (maximum length) and underwent one SWL session only: 62.3% males, median age 48 (21-80) years, mean stone size 9.43 ± 2.9 mm (6.0-20.0), mean density 1210 ± 135 HU (1000-1558). There were 39 (63.9%) cases of SF, 16 (26.2%) of partial success and six (9.8%) of no success. Stone size was the only independent predictor of fragmentation, OR = 1.83, 95% CI = 1.32-2.55, p = 0.0003, and SF OR = 1.91, 95% CI = 1.31-2.78, p = 0.008. The best discriminatory stone size on ROC analysis was 1 cm.Conclusion: Stone size was the only significant success predictor in our cohort, with 76% SF rate for stones < 1 cm in 4 weeks follow-up, supporting that renal stones > 1000 HU may be suitable to SWL.