Catheter-Free Urodynamics Testing: Current Insights and Clinical Potential.

Lower urinary tract dysfunction not only interferes with the health-related quality of life of patients but may also lead to acute kidney injury and infections. To assess the bladder, urodynamic studies (UDS) have been implemented but the use of catheters leads to discomfort for the patient. Catheter-free long-term UDS would be useful and a potential solution could be ambulatory wireless devices that communicate via telemetry. Such sensors can detect pressure or volume. Numerous types of potential catheter-free sensors have been proposed for bladder monitoring. Despite substantial innovation in the manufacturing of implantable biomedical electronic systems, such sensors have remained at the laboratory stage due to a number of critical challenges. These challenges primarily concern hermeticity and biocompatibility, sensitivity and artifacts, drift, telemetry, and energy management. Having overcome these challenges, catheter-free ambulatory urodynamic monitoring could combine a synchronized intravesical pressure sensor with a volume analyzer but only the steps of cystometry and volume measurement are currently sufficiently reproducible to simulate UDS results. The measurement of volume by infrared optical sensors, in the form of abdominal patches, appears to be promising and studies are underway to market a telemetric ambulatory urodynamic monitoring system that includes an intravesical pressure sensor. There has been considerable progress in wearable and conformable electronics on many fronts, and continued collaboration between engineers and urologists could quickly overcome current challenges. In addition, to the diagnosis of UDS, such sensors could be useful in the development of a long-term closed-loop neuromodulation system. In this review, we explore the various types of catheter-free bladder sensors, inherent challenges and solutions to overcome these challenges, and the clinical potential of such long-term implantable sensors.

It is Possible to Reduce Ureteral Stent Clogging and Stent-Related Symptoms to Soothe the Pain of the Patient: A Case Report.

Introduction: Ureteral stent obstruction hinders the management of malignant diseases. Adequate stent insertion through an obstructed ureter does not necessarily guarantee renal decompression and stent-related symptoms adversely affect patient comfort. There are two major problems associated with ureteral stents: obstruction and intolerance to the stents. Case Presentation: A 45-year-old woman was treated for cervical cancer with metastatic lymph nodes and ureteral obstruction with chemotherapy, radiotherapy, immunotherapy, and bilateral retrograde stenting. After recurrent stent obstruction, stent replacement was attempted more than 18 times over two years. In addition, stent-related symptoms adversely affected patient comfort. The patient was finally fitted with Superglide 8-French reinforced ureteral stents. Their replacement every six months was viewed by the patient as a relief compared to the all too frequent replacement of the previous stents. Moreover, the customized changes in the shape of Superglide stents improved patient comfort. Discussion: Recent publications tend to indicate that large-lumen ureteral stents are most likely to remain permeable over time. Various modifications of the bladder or endo-ureteral part of double-pigtail stents have been increasingly reported, with the aim of improving their tolerance while maintaining effective drainage. Conclusion: Adaptation of the internal lumen and shape of stents to the characteristics of the tumor and patient measurements appears to be important for increasing the drainage and tolerance of ureteral stents. The top priority for future ureteral stents suitable for malignant diseases should be to integrate these characteristics based on state-of-the-art data.

Investigating the encrustation of reinforced ureteral stents by computational flow dynamic simulations.

PURPOSE: In cases of extrinsic ureteral obstruction, obstruction due to encrustation is particularly detrimental to functioning of the stent. A thorough understanding of the causes that lead to stent encrustation is essential. Computational fluid dynamic (CFD) simulations may provide a reliable screening platform for investigating the interplay between flow processes and encrustation dynamics in stents. METHODS: Using a tailor-made program, we attempted to evaluate a number of reinforced ureteral stents by CFD simulations with an obstructed or unobstructed ureter and steady or discontinuous flow patterns to identify critical regions with abrupt changes in shape susceptible to stagnant flow and encrustation. RESULTS: For the Vortek® and Urosoft stents, the longitudinal opening of the stents confirmed the presence of critical regions. No critical region was observed for the Superglide stent. CFD simulations showed that cavities formed near the critical regions represented patently stagnant flow and were potentially susceptible to the formation of encrusting deposits. Encrustations were greater in the obstructed design than in the unobstructed design. In the model with a suddenly interrupted laminar flow, the peristaltic motion resulted in new discontinuous encrustation areas scattered throughout the entire external and internal surface of the stent. CONCLUSION: The analysis of fluid dynamics through the tested stents confirmed that encrustations are possible in regions of stagnant flow and showed that stent models with the smoothest possible surface are preferable. The discontinuous flow model provided results that are closer to the findings observed in the clinic and should be more often integrated into CFD simulations.

Analysis of Ureteral Tumour Stents for Malignant Ureteral Obstruction: Towards Reshaping an Optimal Stent.

INTRODUCTION: Ureteral obstruction hinders the management of malignant diseases. Adequate stent placement does not necessarily guarantee renal decompression. The stent stiffness may play a major role to maintain patency. We carried out the present study in order to evaluate drainage efficiency by using stents with distinctive degrees of stiffness and to identify the physical factors that could prevent obstruction of the stent in patients with malignant ureteral obstruction (MUO). MATERIALS AND METHODS: We performed an analysis of 150 patients with MUO drainage at a single institution from June 2009 to June 2019. A progressive choice of stents was shaped to overcome each failure by focusing on the criterion of increasingly stiff stents. RESULTS: During the study period, 556 ureteral stent procedures (USP) were analysed separately. The stent failure with obstruction occurred in 23.0% (128/556) of USP at a mean of 4.4±3.6 months and depended on the type of stent. Stent failure occurred in 34.2% (70/205) of Vortek® stents, in 42.9% (15/35) of Urosoft stents, in 15.4% (39/254) of Superglide or ureteral catheters and in 6.5% (4/62) of tandem stents. No significant differences were found between Vortek® and Urosoft stents regarding stent failures, but there were significant differences between Superglide or Tandem stents and Vortek® or Urosoft stents (p<10-7). The study demonstrated that ureteral stent obstruction significantly decreased with a larger lumen or a stiffer stent (p<10-7). CONCLUSION: In the present study, Superglide and tandem stents were the best stents against stent failure, and the lumen and the stiffness of the stent have been shown to be critical factors in controlling patency. The results suggest that the lumen seems more important than the stiffness, and the stiffness would be the only means of keeping the lumen intact. Future stents for MUO should integrate the importance of the lumen of the stent.

10-Year Experience with Reinforced Ureteral Stents for Malignant Ureteral Obstruction.

INTRODUCTION: Malignant ureteral obstruction (MUO) hinders the management of malignant diseases. Indwelling stent is a common method to release renal obstruction, but stent failure with obstruction is frequent. The studies conclude that stent obstruction divides survival by 2 or even 4. We carried out the present study in order to evaluate drainage efficiency and overall survival by using stents with distinctive degrees of stiffness. MATERIALS AND METHODS: We performed an analysis of 156 patients with MUO drainage at a single institution from June 2009 to June 2019. RESULTS: Of the 156 patients, 128 (82.1%) died with a mean survival time of 15.3 ± 14.4 months after the first ureteral stent procedure (USP). In order to study stent failure and overall survival, the patients were divided into 3 groups. Group 1 with patients died soon after only one USP (n=37). Group 2 with patients had more than one USP and no obstruction (n=41). Patients in Group 3 had more than one USP and at least one stent obstruction (n=62). During the study period, 556 USPs were analysed separately. The stent failure with obstruction occurred in 23.0% (128/556) of USP at a mean of 4.4 ± 3.6 months. In case of stent failure, a progressive choice of stents was shaped to overcome each failure by focusing on the criterion of increasingly stiff stents. Patients in Group 1 died soon at mean of 4.9 ± 4.8 months. The mean survival time of patients in Groups 2 and 3 were, respectively, 19.4 ± 11.2 and 21.5 ± 16.3 months (P = 0.19). CONCLUSION: MUO is a serious disease but this study is the first to prevent survival rate from falling by choosing the stent stiffness suitable for the patient. The active detection of stent failure has been shown to be essential for preserving survival.

Characterization of Sonic Hedgehog/Gli1 Signal Expression in Human Ureter Either Un-Stented or Fitted with Double-Pigtail Stent or a Thread.

INTRODUCTION: The Sonic Hedgehog/Gli1 signal is involved in smooth muscle activity. An experiment showed that the double-pigtail stent caused ureteral inflammation and decreased Gli1 expression in smooth muscle cells. The innovative pigtail-suture stent (JFil® or MiniJFil®) with a thin 0.3F suture thread significantly decreased stent-related symptoms. Fortuitously, a dilation of the ureter containing the sutures was discovered, and a previous study confirmed that the sutures caused less ureteral inflammation than the double-pigtail stent. However, the mechanisms involved in the ureteral dilation are still unknown. In this study, we assessed ureteral Gli1 expression in the human ureter when it was un-stunted or when fitted with a double-pigtail stent or a suture thread. MATERIAL AND METHODS: After consent and inclusion of patients in the protocol, nine segments of ureters were collected during cystectomy procedures for bladder cancers. There was no selection or exclusion, and patients with large tumors were included. Gli1 expression was assessed on the histological section to control the reflection of an active hedgehog signal. The expression of Gli1 in smooth muscle cells of the stented ureter was subjectively compared to un-stented ureter. RESULTS: A decrease in the intensity of Gli1 expression of smooth muscle cells was observed in all cases of ureter fitted with a double-pigtail stent. For the un-stunted ureters and the ureters fitted with the thin 0.3F suture thread, Gli1 staining of smooth muscle cells was heterogeneous, and the small number of cases did not allow us to conclude. CONCLUSION: Apart from the cases of ureters fitted with the double-pigtail stent, Gli1 expression of smooth muscle was heterogeneous. The Shh/Gli1 pathway may not be involved in ureteral dilation by the thread. A broader exploration of molecular mechanisms could make it possible to obtain the mechanisms involved in the dilation of the ureter by the thread.

Stiffness Analysis of Reinforced Ureteral Stents Against Radial Compression: In vitro Study.

INTRODUCTION: Malignant ureteral obstruction caused by cancer diseases may induce renal failure. Indwelling stent is a popular method to release renal obstruction. But adequate stent placement across an obstructed ureter does not necessarily guarantee renal decompression. The aim of the study was to compare, in vitro, the physical characteristics and stiffness of several commercially available reinforced ureteral stents and identify the physical factors that could lead to the obstruction of the stent. MATERIAL AND METHODS: The test apparatus used for measurements allowed applying a radial compression force on a segment of the stent to stop a water flow through the lumen of the stent. Some reinforced double-pigtail stents Teleflex Medical, Bard, and Coloplast were evaluated. RESULTS: The best physical-stiffness characteristic was obtained with the Teleflex 8F stent (5.4 N mm-2). The best result against the radial compression was obtained with tandem stents. The radial compressive stresses of the Teleflex stents (4.4 to 5.4 N mm-2) were higher than with the other stents used in the study (1.0 to 2.9 N mm-2). Among the reinforced stents selected in the present study, a wider inner diameter helped increase volumetric flow rate but did not affect the stiffness of the stent. The measurement of inner diameter showed heterogeneity along the tube of some stents. CONCLUSION: The stiffness of the stent appeared to be an important factor to maintain patency with respect to radial compression forces but the inner diameter of the stent and its preservation may be essential parameters to increase the volumetric flow rate. Some reinforced stents tested in the present study confirmed that it is possible to combine stiffness and wide lumen. The use of tandem stents provided the best stiffness against radial compression and the greatest lumen.

Histological Inflammation in Human Ureter either Healthy or Fitted with Double-Pigtail Stent or a Thin 0.3 F Suture Thread: A Preliminary Study.

BACKGROUND: Ureteral stent intolerance reduces patients' quality of life. It has been suggested that changes in the shape of stents could decrease discomfort. In previous studies, the innovative pigtail-suture stent (i.e., JFil® or MiniJFil®) with a thin 0.3 F suture thread significantly decreased stent-related symptoms. Fortuitously, a dilation of the ureter containing the sutures was discovered. In addition, no inflammation was seen on the ureter wall around the suture in endoscopy. In this preliminary study, we assessed ureteral inflammation in the human ureter when it was healthy or when fitted with a double-pigtail stent or a thread. MATERIALS AND METHODS: After consent and inclusion of patients in the protocol, fifteen segments of ureters were collected during cystectomy procedures for bladder tumors. Ureteral inflammation was assessed on the histological section stained with hematoxylin-eosin. Histological grading (cumulative range of 0 to 6) assessing inflammation was performed on the ureter section for mucosa inflammation and inflammation in the muscle layer. RESULTS: A marked ureteral inflammatory reaction was observed in all cases of ureters fitted with a double-pigtail stent with a mean inflammation score of 4.8 ± 0.4. The ureter fitted with the thin suture thread showed inflammation in only one case with a mean inflammation score of 1.8 ± 1.3 (p=0.001). CONCLUSION: Although the study was limited by the small number of patients, it confirmed that the double-pigtail stent induced ureteral inflammation in all cases and the thin 0.3 F suture thread caused less ureteral inflammation than the double-pigtail stent. The concept of material reduction within the urinary tract seems necessary in order to decrease mucosal irritation. The JFil® or the MiniJFil® thread could meet this requirement.

A New Customized Ureteral Stent with Nonrefluxing Silicone End-piece to Alleviate Stent-related Symptoms in Malignant Diseases.

OBJECTIVE: To evaluate the stent-related symptoms using a new customized ureteral stent with a nonrefluxing silicone end-piece. METHODS: By decreasing the amount of material within the bladder, it should be possible to attenuate the stent-related symptoms. To minimize the amount of material, 17 consecutive patients already fitted with a double-pigtail stent for malignant ureteral obstruction agreed to be fitted with a customized stent where the bladder loop was replaced by a nonrefluxing silicone end-piece. The ureteral stent symptom questionnaire was prospectively administered to patients at baseline with double-pigtail stent and Day 15 after customized stent placement. RESULTS: No difficulty in the placement of the customized stent was encountered. No stent failure, no dislodgment and no calcification were observed 6 months after stenting. The scores for the main domain "Urinary symptoms" (34.4 ± 3.6 vs 23.0 ± 7.0; P = .0004) and the question "Global quality of life" (4.4 ± 2.0 vs 2.4 ± 2.1; P = .01) were significantly decreased by the replacement of the double-pigtail stent by the customized stent. CONCLUSION: The customized ureteral stent may constitute an improvement in the field of stent-related symptoms and seems fit for use in its current shape. Studies exploring and exploiting new concepts are greatly required to reduce stent-related symptoms in all patients including those with cancer.

Challenges To Attenuate Ureteric Stent-Related Symptoms: Reflections On The Need To Fashion A New Dynamic Stent Design Consequent Upon A Case Report.

Double-pigtail stent has been widely used in urology for half a century now, but this device reduces the patient's quality of life. Moreover, indwelling stent-related symptoms induce additional suffering to the pre-existing bladder disease. Novel concepts to prevent stent-related symptoms are greatly required. It has been suggested that changes in the size, form and stent positioning could ease discomfort. By decreasing the amount of material within the bladder, it should be possible to attenuate the stent-related symptoms. A customized stent has been developed to alleviate bladder symptoms. The major characteristic of this stent was in the replacement of the bladder part of the double-pigtail stent by a nonrefluxing silicone end-piece. Three months after stenting, the patient complained of sudden discomfort in the bladder area. On the X-ray, the end-pieces of the customized stents seemed to have slipped in the bladder. The customized stents were replaced by new ones after truncating and adjusting their lengths to the exact ureteric length and stent-related symptoms were then improved again. In the field of stent-related symptoms, stent mobility needs more attention than its intravesical position. The case hereby reported illustrates the variations of the symptoms which seem related to the stent mobility, the necessary shaping of the stent and, the possible research avenues for an innovative dynamic ureteric stent.

Ureteral stent obstruction and stent's discomfort are not irreparable damages.

Ureteral stent obstruction is a significant cause of morbidity and mortality from renal failure. Alternative options for decompression include tandem ureteral stents but the amount of material in the bladder may severely impair the quality of life. Following recurrent stent obstruction, a patient was fitted with tandem ureteral stent on both sides with a new nonrefluxing silicone end piece. After this procedure, renal function was improved with normal serum creatinine. The design of the new stent demonstrates the feasibility of the procedure. This new stent currently under prospective evaluation with tolerance questionnaire has demonstrated quite promising results in 10 patients.

MiniJFil®: A New Safe and Effective Stent for Well-Tolerated Repeated Extracorporeal Shockwave Lithotripsy or Ureteroscopy for Medium-to-Large Kidney Stones?

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is recommended for treating staghorn stones or stones measuring > 20 mm. Extracorporeal shockwave lithotripsy (ESWL) or flexible ureteroscopy (URS) may be used as a complement. However, PCNL can cause trauma to the kidney parenchyma, and patients may find a noninvasive procedure, such as ESWL, to be more attractive. OBJECTIVES: The aim of this study was to evaluate the clinical efficiency of MiniJFil® stenting associated with ESWL or second-line URS for the treatment of medium-to-large kidney stones. The MiniJFil® is a stent reduced to a suture of 0.3F attached to a renal pigtail. The entire ureter is occupied only by the suture of the stent. METHODS: We retrospectively analyzed the data of 28 patients. Twenty-four patients had kidney stones measuring > 15 mm (group 1) and four patients had staghorn stones (group 2). All of the patients were fitted with MiniJFil® 2 - 3 weeks before any treatment. ESWL was always our first-line therapy. Stone-free (SF) status was defined as no evidence of stones. RESULTS: In group 1, the mean largest and cumulative stone diameters, respectively, were 18.7 ± 5.7 mm and 45.0 ± 12.0 mm. In group 2, the mean volume was 6,288.4 ± 2,733.0 mm3. The overall SF was 96.4% (100% for group 1 and 75% for group 2). The mean number of sessions of ESWL and URS, respectively, was 1.4 ± 0.7 and 0.8 ± 0.9 in group 1 and 4.0 ± 2.0 and 1.5 ± 1.3 in group 2. The mean times to achieve these rates were 3.2 ± 1.7 months and 5.6 ± 2.3 months for groups 1 and 2, respectively. One patient in group 2 was treated with only three sessions of ESWL. Renal colic was observed in only five patients (17.9%). CONCLUSIONS: MiniJFil® stenting is safe and may be an alternative for the treatment of kidney stones during minimally invasive procedures.

Changing the double-pigtail stent by a new suture stent to improve patient's quality of life: a prospective study.

PURPOSE: Double-pigtail stent intolerance reduces patient's quality of life. By decreasing the amount of material within the bladder, it should be possible to attenuate stent's symptoms. We evaluated the tolerance of a new stent with a dedicated questionnaire. METHODS: The major innovation of the pigtail suture stent (PSS) is in the replacement of the lower part of the double-pigtail stent with a 0.3F suture. A total of 79 consecutive patients agreed to be fitted with a PSS. The double-pigtail stents of 24 patients complaining strongly of symptoms were replaced with PSS (group 1), and 55 other patients were fitted directly with the PSS after an ureteral endoscopic intervention (group 2). The questionnaire was prospectively administered to patients at baseline and Day 15 post-placement. RESULTS: All questionnaires were returned. In group 1, the replacement of the double-pigtail stent with a PSS significantly decreased urinary symptom scores (35.2 ± 7.5 vs. 23.6 ± 5.4; p = 2 × 10(-6)) and pain scores (11.0 ± 3.9 vs. 4.9 ± 3.1; p = 1 × 10(-7)). In group 1, the baseline scores were not significantly different from those of control group with double-pigtail stent. In group 2, the urinary scores with PSS were significantly different from those of baseline without stent. The scores of the two groups fitted with a PSS were not significantly different at Day 15 post-placement. Unexpectedly, following PSS implantation, we observe a clear dilation of the ureter without inflammation around the suture. CONCLUSIONS: The PSS significantly decreases stent's symptoms and constitutes a medical advance in the domain of ureteral stent tolerance.

Hybrid tumour 'oncocytoma-chromophobe renal cell carcinoma' of the kidney: a report of seven sporadic cases.

OBJECTIVES: To determine whether renal hybrid tumours (HT) appear as a specific clinical and radiological entity, as HT are characterized by the association of both oncocytes and chromophobe cells within the same tumour, and have been described in patients with oncocytosis and Birt-Hogg-Dube syndrome. PATIENTS AND METHODS: We reviewed the medical charts of 67 patients who had a partial or radical nephrectomy in our institution for renal oncocytoma (RO, 24), chromophobe renal cell carcinoma (CRCC, 36) and HT (seven), from January 2006 to October 2007. We report the clinical, radiological and pathological characteristics of the seven cases of HT. RESULTS: The mean (range) age of the patients was 56 (41-68) year. None of the seven patients had any suspicion of RO, based on computed tomography (CT). Two patients had a history of kidney cancer. Five patients had partial and two a radical nephrectomy. The mean (range) maximum tumour diameter was 5.5 (1.8-9) cm. Two tumours were pT1a, two were pT1b and three were pT2. Pathological analysis showed RO-like and CRCC-like cells intermixed (six patients) or distinct (one). After a median (range) follow-up of 20 (8-25) months, none of the patients had any evidence of disease recurrence. CONCLUSIONS: In a large series of patients with sporadic RO and CRCC, 10% of the tumours had hybrid morphological features, as described in oncocytosis and Birt-Hogg-Dube syndrome. We were unable to identify any specific clinical characteristic. Most importantly, none of these HT showed any of the radiological characteristics of RO.

Gain-of-glycosylation mutations.

Disease-causing missense (and other in-frame) mutations can exert their deleterious effects at the cellular level through multiple mechanisms. A pathogenic mechanism involves the addition of a novel N-linked glycan. Up to 1.4% of known disease-causing missense mutations are predicted to give rise to gains-of-glycosylation. For some of these mutations, the novel glycans have been shown to be both necessary and sufficient to account for the deleterious impact of the mutation. The chemical complementation of cells from patients in vitro with various modifiers of glycosylation has been demonstrated and raises the possibility of specific chemical treatments for patients bearing gain-of-glycosylation mutations.

Coloepiploic mobilization during left radical nephrectomy for renal cell carcinoma is indicated to reduce the risk of iatrogenic splenectomy.

OBJECTIVES: To determine whether coloepiploic mobilization (CEM) is indicated to reduce the incidence of iatrogenic splenectomy during left radical nephrectomy for renal cell carcinoma. The incidence of iatrogenic splenectomy during a left nephrectomy is estimated to be between 1.4% and 24%. In a recent study, we reported that the incidence of iatrogenic splenectomy was 8% during a left nephrectomy performed for renal cell carcinoma through a transperitoneal anterior subcostal incision. METHODS: A left radical nephrectomy was performed in 233 consecutive patients for renal cell carcinoma through a transperitoneal anterior subcostal incision with a CEM procedure in which the left colonic flexure was completely detached from the epiploa. Perioperative and postoperative complications, including splenic injury, were noted in a database. The mean patient age was 51.3 years (range 21.3 to 90.2). The mean tumor size was 58 mm (range 15 to 230). RESULTS: An iatrogenic splenectomy was required in 3 patients, and in 1 patient, a splenic injury was treated conservatively. The incidence of iatrogenic splenectomy accompanying left radical nephrectomy was 1.3%. The mean operative time was 120 minutes (range 80 to 240). The mean time to normal gut motility was 3.4 days (range 2 to 11) and to discharge from the hospital it was 9.3 days (range 6 to 19). Regarding CEM, we did not observe any significant abdominal complications. CONCLUSIONS: The incidence of iatrogenic splenectomy during a left radical nephrectomy through a transperitoneal anterior subcostal incision may be reduced by performing the technique of CEM.

Nephron sparing surgery for renal cell carcinoma using selective renal parenchymal clamping.

PURPOSE: We describe a technical artifice facilitating nephron sparing surgery for renal cell carcinoma without clamping the renal pedicle. MATERIALS AND METHODS: Selective renal parenchymal clamping was performed using a large curved DeBakey aortic clamp placed around and sufficiently far from the tumor. The lesion was resected with a surrounding margin of normal renal parenchyma. The intrarenal vessels were suture ligated and the collecting system was closed as necessary. Time was not limited since the artery was not clamped. RESULTS: Ten patients with renal cell carcinoma in whom nephron sparing surgery was indicated underwent selective renal parenchymal clamping. The indication was elective in 8 patients and urgent in 2. The tumor was at the renal pole in 3 cases and peripheral in 7. Mean tumor size was 32 mm. (range 19 to 52). Blood loss was insignificant. Operative time was 81 minutes (range 61 to 125) and there were no perioperative or postoperative complications. CONCLUSIONS: Selective renal parenchymal clamping is a simple and efficient technical maneuver for facilitating nephron sparing surgery without pedicle dissection and clamping for renal peripheral or pole tumors. Neoplasm location and size are the limiting factors of this technique.