#05 Newsletter October 23, 2021

Hello and welcome to the stone newsletter, where we discuss every 2 months the most recent and relevant studies in stone disease.

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Themes introduction

Welcome to this fall edition of Stone News. As the COVID pandemic has particularly affected urolithiasis patients(especially stented patients), we first review a new grading system for encrusted stents that may help the urologist in planning the surgery as well as in counselling patients.

We then discuss a new approach, using alpha blockers, to avoid ureteral damage due to insertion of a ureteral access sheath.

Finally, we evaluate a multicentre study on supine PCNL in horseshoe kidneys – an uncommon approach to a quite common anatomical variation.

I hope that this edition of Stone News will improve not only the care of our patients, but also of ourselves.

img A Novel Visual Grading for Ureteral Encrusted Stent Classification to Help Decide the Endourologic Treatment img 2'
https://pubmed.ncbi.nlm.nih.gov/33730863// img

In this review the authors propose a new grading system for encrusted stents based on their visual appearance. According to the severity of the encrustations, cases are classified into four categories, A to D. Each category has subclassifications to allow identification of the exact scenario, taking into account the proximal and distal coils, the shaft and the thickness of the calcifications.

To assess the grading system, 140 patients with encrusted stents were treated in multiple institutions, correlating the results and success rates with the classification. The encrusted stents could be removed in 86% of cases. Those classified as type A or B could be removed in 100% of cases, while type C could be removed in 91% and type D in 70%, most of the latter cases requiring a second look. Type A encrusted stents were predominantly and effectively treated with cystolithotripsy, type B with ureteroscopy and types C and D with combined access. The complication rate increased linearly from type A to type D.

Compared with other currently used classifications, this system allows the surgeon to plan the procedure adequately and to counsel patients regarding success rates for stent retrieval, potential complications and the need for ancillary procedures.

img Silodosin for Prevention of Ureteral Injuries Resulting from Insertion of a Ureteral Access Sheath: A Randomized Controlled Trial img 3'
https://pubmed.ncbi.nlm.nih.gov/33741297/ img

The ureteral access sheath, commonly used in flexible ureteroscopy, allows the urologist to achieve safe and quick access to the kidney while maintaining low intrarenal pressures. However, this advantage comes at the risk of ureteral damage due to the access sheath insertion. To avoid such damage, it is currently recommended that the smallest access sheath possible be used, which in the vast majority of cases is a 10/12 Fr sheath. Recently, the only proven method to reduce ureteral damages due to access sheath insertion was to present patients (with the troubles that it carries as extra OR time and stent symptoms).[r1] Based on the hypothesis that passive ureteral dilation may be achieved with alpha blockers, this interesting paper reports the results of a randomized controlled trial designed to evaluate the effectiveness of silodosin in decreasing injuries due to ureteral access sheath insertion.

Eighty-seven patients were randomized into control and treatment groups, the latter receiving 8 mg silodosin once daily for 3 days prior to surgery. Standard flexible ureteroscopy was performed, attempting to insert a 11/13 Fr access sheath in all patients.

The control and treatment groups were comparable in all variables evaluated and overall ureteral lesions were reported in 50% of cases. Significant lesions (grade 2 or above) were seen in four patients in the silodosin group and 12 patients in the control group (p=0.031). Overall complications, operative time, stone-free rate and hospital stay were similar in the two groups, but pain scores were significantly higher in the control group. In the subgroup analysis, silodosin was more effective in preventing ureteral damage in patients aged <55 years.

The results of this trial indicate that giving silodosin to prevent ureteral wall injuries may be good practice and that such treatment has the further advantage of decreasing pain after surgery.

img Percutaneous Nephrolithotomy in Horseshoe Kidneys: Results of a Multicentric Study img 3'
https://pubmed.ncbi.nlm.nih.gov/32292038/ img

Horseshoe kidneys are the most common kidney anomaly, occurring in 1 in 600 births. The condition characteristically involves fusion between the lower poles, but many anatomical variations may be encountered, such as high insertion of the ureteropelvic junction and malrotation of the calyces. In the context of the latter finding, it is common practice to perform prone PCNL to treat kidney stones.

This study retrospectively evaluated PCNL procedures from 12 centres performed over a period of 10 years and assessed the impact of patient position during the operation as a secondary outcome. Each centre chose the surgical position based on local protocols. In the 81 included patients, 106 PCNLs were performed: 67 in the prone position and 39 in the supine position. The two groups were comparable except with regard to BMI, which was higher in the prone group. Final stone-free rate was assessed on the basis of absence of stone fragments >4 mm. The overall immediate stone-free rate was 54.7%, and the final success rate increased to 72.4% after a mean of 0.24 secondary procedures. Prone PCNL had a final stone-free rate of 66.1% compared with 82.1% for supine PCNL (although the difference was not significant).

The upper calyx was the main approach in 80% of patients in the prone group compared with 43% in the supine group. Surgical time was significantly longer in the prone group (126 vs 100 min). Overall complication rates were comparable, at 16.9% for the prone group and 18.4% for the supine group. Most complications were Clavien 1 and 2 (8% of patients in the prone group and 0% in the supine group had Clavien 3 complications).

This interesting study challenges the dogma that exclusively prone PCNL should be performed in horseshoe kidney patients, demonstrating that the supine position may be suitable. This is especially interesting as supine PCNL has gained much popularity over the years. Nonetheless, it is important to point out that endourologists must know both techniques and that patient position should be chosen in accordance with the best interests of the patient, i.e. in order to achieve the most efficient results with fewer complications.

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