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The Nuffield Department of Surgical Sciences is the academic department of surgery at the University of Oxford, and hosts a multidisciplinary team of senior clinical academic surgeons, senior scientists, junior clinicians and scientists in training.
A new model with an anatomically accurate human renal collecting system for training in fluoroscopy-guided percutaneous nephrolithotomy access.
BACKGROUND AND PURPOSE: Obtaining renal access is one of the most important and complex steps in learning percutaneous nephrolithotomy (PCNL). Ideally, this skill should be practiced outside the operating room. There is a need for anatomically accurate and cheap models for simulated training. The objective was to develop a cost-effective, anatomically accurate, nonbiologic training model for simulated PCNL access under fluoroscopic guidance. METHODS: Collecting systems from routine computed tomography urograms were extracted and reformatted using specialized software. These images were printed in a water-soluble plastic on a three-dimensional (3D) printer to create biomodels. These models were embedded in silicone and then the models were dissolved in water to leave a hollow collecting system within a silicone model. These PCNL models were filled with contrast medium and sealed. A layer of dense foam acted as a spacer to replicate the tissues between skin and kidney. RESULTS: 3D printed models of human collecting systems are a useful adjunct in planning PCNL access. The PCNL access training model is relatively low cost and reproduces the anatomy of the renal collecting system faithfully. A range of models reflecting the variety and complexity of human collecting systems can be reproduced. The fluoroscopic triangulation process needed to target the calix of choice can be practiced successfully in this model. CONCLUSIONS: This silicone PCNL training model accurately replicates the anatomic architecture and orientation of the human renal collecting system. It provides a safe, clean, and effective model for training in accurate fluoroscopy-guided PCNL access.
Management of iatrogenic ureteric injury with retrograde ureteric stenting: an analysis of factors affecting technical success and long-term outcome.
Background Iatrogenic ureteral injuries arise as serious complication following obstetrics, gynecological, general, and urological surgery with incidence in the range of 0.5-10%. Retrograde placement of double-J ureteric stent is a possible treatment option if the injury is not recognized at the time of surgery. Purpose To assess technical success and long-term outcome associated with retrograde ureteric stent insertion for iatrogenic ureteric injury. Material and Methods Between 1999 and 2011, 26 patients with initially unrecognized iatrogenic ureteric injury underwent initial management with retrograde ureteric stenting. Full case-notes were available for review in 25 patients. Results The mean interval from injury to attempted stenting was 19.4 days. Successful retrograde ureteric stenting was achieved in 21/25 patients (81%). Retrograde stenting failed in four patients, and nephrostomy followed by alternative procedures were performed instead. At a median follow-up interval of 9.7 months, normal anatomy was demonstrated on 12/21 patients (57%) and a stricture was observed in 6/21 patients (28%) with three requiring surgical intervention. Conclusion Retrograde stenting is a safe and efficient initial management in patients with iatrogenic ureteric injuries.
Smartphone apps for urolithiasis.
There are an increasing number of healthcare smartphone applications ('apps') available. Urolithiasis presents a major healthcare burden. Patients are increasingly keen to educate themselves regarding the diagnosis and management of their condition. There is no formal regulation of healthcare apps, including a large number of apps relating to urolithiasis. This review aims to examine the range of apps available, and the prevalence of healthcare professional input. Four international smartphone app stores were searched: Apple's App Store, Google Play (Android), BlackBerry App World and the Windows Phone App store. A total of 42 unique apps were downloaded and analysed. Recorded data included the cost (£/$), publisher information, number of ratings, average rating and any documentation of medical professional involvement. Twenty-one (50%) apps required payment for download. The mean cost was £3.58 ($6.04) with range £0.61-£34.90 ($1.03-$58.87). Thirty-three (79%) of the 42 apps were designed to be used by patients. Fifteen (36%) of the 42 apps had clear input from health professionals. Twenty-two apps offered patient information, including dietary advice on lowering calcium intake, which is contrary to current evidence-based practice. We conclude that urolithiasis apps have future potential to inform both patients and healthcare professionals on stone management. However, inaccuracies in the recommendations made by some apps can be misleading or even harmful due to a lack of specialist involvement. We recommend improving the usefulness of these apps by seeking a 'quality stamp' from recognised urological organisations and greater clinician involvement in future app development.
A Drosophila genetic model of nephrolithiasis: transcriptional changes in response to diet induced stone formation.
BACKGROUND: Urolithiasis is a significant healthcare issue but the pathophysiology of stone disease remains poorly understood. Drosophila Malpighian tubules were known to share similar physiological function to human renal tubules. We have used Drosophila as a genetic model to study the transcriptional response to stone formation secondary to dietary manipulation. METHODS: Wild-type male flies were raised on standard medium supplemented with lithogenic agents: control, sodium oxalate (NaOx) and ethylene glycol (EG). At 2 weeks, Malpighian tubules were dissected under polarized microscope to visualize crystals. The parallel group was dissected for RNA extraction and subsequent next-generation RNA sequencing. RESULTS: Crystal formation was visualized in 20%(±2.2) of flies on control diet, 73%(±3.6) on NaOx diet and 84%(±2.2) on EG diet. Differentially expressed genes were identified in flies fed with NaOx and EG diet comparing with the control group. Fifty-eight genes were differentially expressed (FDR <0.05, p
Efficacy of the lithotripsy in treating lower pole renal stones
Use of extracorporeal lithotripsy is declining in North America and many European countries despite international guidelines advocating it as a first-line therapy. Traditionally, lithotripsy is thought to have poor efficacy at treating lower pole renal stones. We evaluated the success rates of lithotripsy for lower pole renal stones in our unit. 50 patients with lower pole kidney stones ≤15 mmtreated between 3/5/11 and 19/4/12 were included in the study. Patients received lithotripsy on a fixed-site Storz Modulith SLX F2 lithotripter according to a standard protocol. Clinical success was defined as stone-free status or asymptomatic clinically insignificant residual fragments (CIRFs) ≤3 mm at radiological follow-up. The mean stone size was 7.8 mm. The majority of stones (66 %) were between 5 and 10 mm. 28 % of stones were between 10 and 15 mm.For solitary lower pole stones complete stone clearance was achieved in 63 %. Total stone clearance including those with CIRFs was achieved in 81 % of patients. As expected, for those with multiple lower pole stones the success rates were lower: complete clearance was observed in 39 %and combined clearance including those with CIRFs was 56 %. Overall, complete stone clearance was observed in 54 % of patients and clearance with CIRFs was achieved in 72 % of patients. Success rate could not be attributed to age, stone size or gender.Our outcome data for the treatment of lower pole renal stones (≤15 mm) compare favourably with the literature. With this level of stone clearance, a non-invasive, outpatientbased treatment like lithotripsy should remain the first-line treatment option for lower pole stones. Ureteroscopy must prove that it is significantly better either in terms of clinical outcome or patient satisfaction to justify replacing lithotripsy. © Springer-Verlag Berlin Heidelberg 2013.
Smartphone apps for urolithiasis
There are an increasing number of healthcare smartphone applications (‘apps’) available. Urolithiasis presents a major healthcare burden. Patients are increasingly keen to educate themselves regarding the diagnosis and management of their condition. There is no formal regulation of healthcare apps, including a large number of apps relating to urolithiasis. This review aims to examine the range of apps available, and the prevalence of healthcare professional input. Four international smartphone app stores were searched: Apple’s App Store, Google Play (Android), BlackBerry App World and the Windows Phone App store. A total of 42 unique apps were downloaded and analysed. Recorded data included the cost (£/$), publisher information, number of ratings, average rating and any documentation of medical professional involvement. Twenty-one (50 %) apps required payment for download. The mean cost was £3.58 ($6.04) with range £0.61–£34.90 ($1.03–$58.87). Thirty-three (79 %) of the 42 apps were designed to be used by patients. Fifteen (36 %) of the 42 apps had clear input from health professionals. Twenty-two apps offered patient information, including dietary advice on lowering calcium intake, which is contrary to current evidence-based practice. We conclude that urolithiasis apps have future potential to inform both patients and healthcare professionals on stone management. However, inaccuracies in the recommendations made by some apps can be misleading or even harmful due to a lack of specialist involvement. We recommend improving the usefulness of these apps by seeking a ‘quality stamp’ from recognised urological organisations and greater clinician involvement in future app development.
The COVID Stones Collaborative: How has the Management of Ureteric Stones Changed During and After the COVID-19 Pandemic? Rationale and Study Protocol
Background and objectives The coronavirus disease 2019 (COVID-19) pandemic is having a significant impact on healthcare delivery. As a result, management of patients with ureteric stones has likely been affected. We report our study protocol for the investigation of ureteric stone management during and after the COVID-19 pandemic. Material and methods The COVID Stones study is a multicenter national cohort study of the management and outcomes of patients with ureteric stones before, during, and after the COVID-19 pandemic in the United Kingdom. The study will consist of three data collection periods, pre-pandemic (“pre-COVID”), pandemic (“COVID”), and post-pandemic (“post-COVID”). This will allow quantification of what “normal” was, how this has changed, and to capture any persisting changes in management. The primary outcome evaluating the success rate of the initial treatment decision will be assessed following a 6-month follow-up from the time of first presentation and will be performed for each recruited patient from each of the three data collection periods. This will allow comparison between both management and outcomes before, during, and after the pandemic. Conclusions We anticipate that this study will lead to an increased understanding of the impact of the outcomes of emergency management of ureteric stones following changes in clinical practice due to the COVID-19 pandemic health provision restrictions.
Predicting shockwave lithotripsy outcome for urolithiasis using clinical and stone computed tomography texture analysis variables.
We aimed to develop and evaluate a statistical model, which included known pre-treatment factors and new computed tomography texture analysis (CTTA) variables, for its ability to predict the likelihood of a successful outcome after extracorporeal shockwave lithotripsy (SWL) treatment for renal and ureteric stones. Up to half of patients undergoing SWL may fail treatment. Better prediction of which cases will likely succeed SWL will help patients to make an informed decision on the most effective treatment modality for their stone. 19 pre-treatment factors for SWL success, including 6 CTTA variables, were collected from 459 SWL cases at a single centre. Univariate and multivariable analyses were performed by independent statisticians to predict the probability of a stone free (both with and without residual fragments) outcome after SWL. A multivariable model had an overall accuracy of 66% on Receiver Operator Curve (ROC) analysis to predict for successful SWL outcome. The variables most frequently chosen for the model were those which represented stone size. Although previous studies have suggested SWL can be reliably predicted using pre-treatment factors and that analysis of CT stone images may improve outcome prediction, the results from this study have not produced a useful model for SWL outcome prediction.
Genetic variants of calcium and vitamin D metabolism in kidney stone disease.
Kidney stone disease (nephrolithiasis) is a major clinical and economic health burden with a heritability of ~45-60%. We present genome-wide association studies in British and Japanese populations and a trans-ethnic meta-analysis that include 12,123 cases and 417,378 controls, and identify 20 nephrolithiasis-associated loci, seven of which are previously unreported. A CYP24A1 locus is predicted to affect vitamin D metabolism and five loci, DGKD, DGKH, WDR72, GPIC1, and BCR, are predicted to influence calcium-sensing receptor (CaSR) signaling. In a validation cohort of only nephrolithiasis patients, the CYP24A1-associated locus correlates with serum calcium concentration and a number of nephrolithiasis episodes while the DGKD-associated locus correlates with urinary calcium excretion. In vitro, DGKD knockdown impairs CaSR-signal transduction, an effect rectified with the calcimimetic cinacalcet. Our findings indicate that studies of genotype-guided precision-medicine approaches, including withholding vitamin D supplementation and targeting vitamin D activation or CaSR-signaling pathways in patients with recurrent kidney stones, are warranted.
Mitigating infections in implantable urological continence devices: risks, challenges, solutions, and future innovations. A comprehensive literature review.
PURPOSE OF REVIEW: Stress urinary incontinence is a growing issue in ageing men, often following treatment for prostate cancer or bladder outflow obstruction. While implantable urological devices offer relief, infections are a significant concern. These infections can lead to device removal, negating the benefits and impacting patient outcomes. This review explores the risks and factors contributing to these infections and existing strategies to minimize them. These strategies encompass a multifaceted approach that considers patient-specific issues, environmental issues, device design and surgical techniques. However, despite these interventions, there is still a pressing need for further advancements in device infection prevention. RECENT FINDINGS: Faster diagnostics, such as Raman spectroscopy, could enable early detection of infections. Additionally, biocompatible adjuncts like ultrasound-responsive microbubbles hold promise for enhanced drug delivery and biofilm disruption, particularly important as antibiotic resistance rises worldwide. SUMMARY: By combining advancements in diagnostics, device design, and patient-specific surgical techniques, we can create a future where implantable urological devices offer men a significant improvement in quality of life with minimal infection risk.
MI-UNet: Improved Segmentation in Ureteroscopy
© 2020 IEEE. Ureteroscopy has evolved into a routine technique for treatment of kidney stones. Laser lithotripsy is commonly used to fragment the kidney stones until they are small enough to be removed. Poor image quality, presence of floating debris and severe occlusions in the endoscopy video make it difficult to target stones during the ureteroscopy procedure. A potential solution is automated localization and segmentation of the stone fragments. However, the heterogeneity of stones in terms of shape, texture, as well as colour and the presence of moving debris make the task of stone segmentation challenging. Further, dynamic background, motion blur, local deformations, occlusions and varying illumination conditions need to be taken into account during segmentation. To address these issues, we compliment state-of-the-art U-Net based segmentation strategy with the learned motion information. This technique leverages difference in motion between the large stones and surrounding debris and additionally tackles problems due to illumination variability, occlusions and other factors that are present in the frame-of-interest. The proposed motion induced U-Net (MI-UNet) architecture consists of two main components: 1) U-Net and 2) DVFNet. The quantitative results show consistent performance and improvement over most evaluation metrics. The qualitative validation also illustrate that our complimentary DVFNet is able to effectively reduce the effect of surrounding debris in contrast to U-Net.
Motion induced segmentation of stone fragments in ureteroscopy video
© 2020 SPIE. Ureteroscopy is a conventional procedure used for localization and removal of kidney stones. Laser is commonly used to fragment the stones until they are small enough to be removed. Often, the surgical team faces tremendous challenge to successfully perform this task, mainly due to poor image quality, presence of floating debris and occlusions in the endoscopy video. Automated localization and segmentation can help to perform stone fragmentation efficiently. However, the automatic segmentation of kidney stones is a complex and challenging procedure due to stone heterogeneity in terms of shape, size, texture, color and position. In addition, dynamic background, motion blur, local deformations, occlusions, varying illumination conditions and visual clutter from the stone debris make the segmentation task even more challenging. In this paper, we present a novel illumination invariant optical flow based segmentation technique. We introduce a multi-frame based dense optical flow estimation in a primal-dual optimization framework embedded with a robust data-term based on normalized correlation transform descriptors. The proposed technique leverages the motion fields between multiple frames reducing the effect of blur, deformations, occlusions and debris; and the proposed descriptor makes the method robust to illumination changes and dynamic background. Both qualitative and quantitative evaluations show the efficacy of the proposed method on ureteroscopy data. Our algorithm shows an improvement of 5-8% over all evaluation metrics as compared to the previous method. Our multi-frame strategy outperforms classically used two-frame model.
A temperature model for laser lithotripsy.
OBJECTIVE: To derive and validate a mathematical model to predict laser-induced temperature changes in a kidney during kidney stone treatment. METHODS: A simplified mathematical model to predict temperature change in the kidney for any given renal volume, irrigation flow rate, irrigation fluid temperature, and laser power was derived. We validated our model with matched in vitro experiments. RESULTS: Excellent agreement between the mathematical model predictions and laboratory data was obtained. CONCLUSION: The model obviates the need for repeated experimental validation. The model predicts scenarios where risk of renal tissue damage is high. With real-time knowledge of flow rate, irrigating fluid temperature and laser usage, safety warning levels could be predicted. Meanwhile, clinicians should be aware of the potential risk from thermal injury and take measures to reduce the risk, such as using room temperature irrigation fluid and judicious laser use.