Purpose: We assessed the literature around post-treatment asymptomatic residual stone fragments and performed a meta-analysis. The main outcomes were intervention rate and disease progression. Materials and Methods: We searched OvidÒ, MEDLINEÒ, EmbaseÔ, the Cochrane Library and ClinicalTrials.gov using search terms: "asymptomatic", "nephrolithiasis", "ESWL", "PCNL", "URS" and "intervention." Inclusion criteria were all studies with residual renal fragments following treatment (shock wave lithotripsy, ureteroscopy or percutaneous nephrolithotomy). Analysis was performed using 'metafor' in R and bias determined using NewcastleeOttawa scale. Results: From 273 articles, 18 papers (2,096 patients) had details of intervention rate for residual fragments. Aggregate intervention rates for 4 mm fragments rose from 19% (20 months) to 22% (50 months), while >4 mm fragments rose from 22% to 47%. Aggregate disease progression rates for 4 mm rose from 25% to 47% and >4 mm rose from 26% to 88%. However, there was substantial difference in definition of "disease progression." Meta-analysis comparing >4 mm against 4 mm fragments: intervention rate for >4 mm (vs 4 mm): OR[1.50 (95% CI 0.70e2.30), p <0.001, I 2 [67.6%, tau 2 [0.48, Cochran's Q [11.4 (p[0.02) and Egger's regression: z[3.11, p[0.002. Disease progression rate for >4 mm: OR[0.06 (95% CI À0.98e1.10), p[0.91, I 2 [53.0%, tau 2 [0.57, Cochran's Q[7.11 (p[0.07) and Egger's regression: z[À0.75, p[0.45. Bias analysis demonstrated a moderate risk. Conclusions: Larger post-treatment residual fragments are significantly more likely to require further intervention especially in the long term. Smaller fragments, although less likely to require further intervention, still carry that risk. Notably, there is no significant difference in disease progression between fragment sizes. Patients with residual fragments should be appropriately counselled and informed decision-making regarding further management should be done.

Objective To systematically review the natural history of small asymptomatic kidney and residual stones, as the incidental identification of small, asymptomatic renal calculi has risen with increasing use of high‐resolution imaging. Materials and methods We reviewed the natural history of small asymptomatic kidney and residual stones using the Cochrane and Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) methodology. We searched MEDLINE, Scopus, EMBASE, EBSCO, Cochrane library and Clinicaltrials.gov using themes of ‘asymptomatic’, ‘nephrolithiasis’, ‘observation’, ‘symptoms’, ‘admission’, ‘intervention’ and similar allied terms for all English language articles from 1996 to 2020 (25 years). Inclusion criteria were studies with ≥50 patients, stones ≤10 mm, and a mean follow‐up of ≥24 months. Primary outcomes were occurrence of symptoms, emergency admission, and interventions. Results Our literature search returned 2247 results of which 10 papers were included in the final review. Risk of symptomatic episodes ranged from 0% to 59.4%. Meta‐analysis did not identify any significant difference in the likelihood of developing symptoms when comparing stones <5 mm to those >5 mm, nor those <10 mm to those >10 mm. Risk of admission varied from 14% to 19% and the risk of intervention from 12% to 35%. Meta‐analysis showed a significantly decreased likelihood of intervention for stones <5 vs >5 mm and <10 vs >10 mm. Studies had variable risk of bias due to heterogeneous reporting of outcome measures with significant likelihood that observed differences in results were compatible with chance alone (Symptoms: I2=0%, Cochran’s Q = 3.09, P = 0.69; Intervention: I2=0%, Cochran’s Q = 1.76, P = 0.88). Conclusions The present systematic review indicates that stone size is not a reliable predictor of symptoms; however, risk of intervention is greater for stones >5mm vs <5 mm and >10 vs <10 mm. This review will inform urologists as they discuss management strategies with patients who have asymptomatic renal stones and offer insight to committees during the development of evidence‐based guidelines.

investigate the role of Fabp4 on urolithiasis. 2)An in vitro study using murine renal tubular cells (RTC) was conducted to examine calcium oxalate crystallization via Fabp4. We compared the control group with the Fabp4 knockdown group after 6 hours exposure of calcium oxalate monohydrate (COM).RESULTS: 1)The Fabp4 KO mice had significantly larger amounts of renal crystal deposits and urinary crystal than the WT mice. Additionally, the gene expression level of Ccl2 was lower in the Fabp4 KO mice than in the WT mice (figure 1A). The RNA-sequence result demonstrated that there were 16 genes commonly differentiated (>2fold) before and after renal crystal development in the Fabp4 KO mice compared with the WT mice. These genes were associated with downregulation of antioxidant activity, IgA binding, and Toll-like receptor binding; cell-cell adhesion and neutrophil aggregation; and IgA immunoglobulin complex in Gene Ontology analysis.2)In the Fabp4 knockdown RTC, COM crystal endocytosis rate was significantly lower than the control. Gene expression levels of Ccl2 and Tumor necrosis factor were higher in the Fabp4 knockdown RTC than those of the control (figure 1B).CONCLUSIONS: We have found that Fabp4 deficiency suppresses macrophage function and crystal endocytosis in renal tubular stones, leading to stone development. These data support a causal role for FABP4 in driving urinary stone formation.

We present preliminary stone ablation rate results from an automated bench model using two pulse-modulated Ho:YAG lasers and a thulium fibre laser (TFL) in contact and non-contact modes. Ablation rate was assessed using automated apparatus that moved the laser fibre across flat BegoStone phantoms at a constant stone-to-fibre working distance (WD). Pre-soaked and unsoaked stones were used. A range of powers (20–60 W) was tested at WD of up to 3 mm. In pseudocontact, the prototype Ho:YAG laser produced higher ablation than the reference Ho:YAG laser at all powers tested (p < 0.002), and higher ablation than TFL at 20 W and 40 W (p < 0.001). At distance, ablation rates for the prototype were higher than the reference Ho:YAG laser using pre-soaked stones at WD up to 3 mm (p < 0.001). TFL required the laser fibre to be moved faster (5–12 mm/s) for optimal ablation, compared to 1–3 mm/s for the Ho:YAG lasers. TFL was unable to demonstrate ablation with unsoaked BegoStone. At any given power, similar ablation rates were achievable with all three lasers under optimised conditions. Novel pulse-modulation modes demonstrated higher ablation rates than the reference Ho:YAG laser’s pulse-modulation at a range of powers and WDs. Ablation rate of Ho:YAG lasers decreased linearly with WD whereas the ablation rate of TFL decreased rapidly beyond 2 mm WD. TFL was more affected by scan speed and pre-soaking of stone than Ho:YAG lasers. Ho:YAG lasers may be more practical in clinical settings because they are less dependent on ablation technique.

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