Clinical Research Directory

Renal Structural and Functional Alterations Following Repeated Ureteroscopic Procedures: An Exploratory Multimodal Imaging Study

Introduction and objectives Saline irrigation and instrumentation during Retrograde Intrarenal Surgery (RIRS) causes elevation of intrarenal pressure (IRP) inducing intrarenal backflow (IRB). In an experimental study from 2025 Hinojosa-Gonzalez et al. demonstrated an association between elevated IRP and increased risk of bacteremia. The potential of elevated IRP and IRB to breach physiological barriers and facilitate systemic translocation of renal pelvic contents warrants investigation into their effects on parenchymal integrity and function. Using contrast-enhanced MRI in a porcine model, Lildal et al. (2023) demonstrated segmental IRB with sharply demarcated areas of contrast distribution, predominantly at the renal poles. The preferential involvement of renal poles resembles the distribution of renal scarring observed in reflux nephropathy, raising the hypothesis that repeated pressure-related exposure may contribute to localized parenchymal alterations. However, whether repeated ureteroscopic procedures are associated with similar persistent regional changes in renal structure and function remains unclear. We therefore initiated an exploratory clinical study assessing renal structure and function following multiple ureteroscopic procedures using multiparametric MRI, DMSA scintigraphy and ultrasound elastography. Materials and methods This exploratory cross-sectional case-control study aims to enroll 10 patients with repeated unilateral ureteroscopic procedures and 10 healthy controls. Eligible patients must have undergone ≥3 ipsilateral procedures (RIRS/URS/URSL) and ≤1 contralateral procedure. Major exclusions include solitary kidney, metabolic or structural renal disorders compromising MRI analysis, chronic UTI, previous multiple PCNL procedures, and MRI contraindications. All participants undergo serum creatinine measurement and multiparametric renal MRI (1.5T Philips Ingenia), including T1 mapping, heavily T2-weighted 3D imaging, diffusion-weighted imaging, T2\* imaging, and renal arterial flow assessment. Renal scintigraphy is performed using ⁹⁹ᵐTc-DMSA, with planar imaging for quantification of split renal function and SPECT for evaluation of cortical scarring. Bilateral renal shear-wave elastography (Mindray Resona I9 ultrasound system) is conducted to quantify regional parenchymal stiffness in five predefined regions per kidney. Planned analyses will compare regional imaging parameters between patients and controls and between ipsilateral and contralateral kidneys, accounting for within-subject correlation. Segmental imaging parameters will be compared between groups and kidneys using linear mixed-effects models accounting for repeated measurements within subjects.

Stone Clearance With Aspiration vs Other Technologies: a Real-world Evidence Study

The goal of this clinical trial is to evaluate the effectiveness and safety of Steerable Ureteroscopic Renal Evacuation (SURE) with the CVAC System versus other commonly used renal-stone interventions.

Trial of Ureteroscopy vs Steerable Continuous Flow Aspiration Technology

The goal of this clinical trial is to compare Steerable Ureteroscopic Renal Evacuation (SURE) using the CVAC System and standard ureteroscopy (URS) with laser lithotripsy for the treatment of urolithiasis. This is a prospective, randomized (1:1), multi-center study.

A Retrospective, Multi-center Real-world Study of Steerable Ureteroscopic Renal Evacuation (SURE) Procedure With the CVAC® System

This is a retrospective, multi-center collaboration to assess real-world outcomes of a novel steerable aspiration system, the CVAC® System ("CVAC"), and flexible and navigable suction ureteral access sheath (FANS) for the treatment of urinary stones.

Urine Biomarker for Stone Recurrence

Despite the advent of treating stones with Extracorporeal Shock Wave Lithotripsy (ESWL) and Percutaneous nephrolithotomy (PCNL), the recurrence rate for renal stones remains high and this may be due to poor compliance of patients with dietary and fluid advice, age, metabolic abnormalities, medicines and the formation of "new stones" from clinically insignificant residual fragments (CIRF). Though some patients become stone-free after ESWL/PCNL or open surgeries, the majority develop "new stones" and it is difficult to predict when these stones will recur until either they have imaging perform or they developed symptoms. However, the use of regular imaging for monitoring will be costly and involve radiation exposure. Therefore, a diagnostic tool is needed to enable the clinician and/or patient to monitor for stone recurrence. In the previous studies, some urine markers were identified that are related to stone formation. The relationship of these urine markers with the recurrence of renal stone will be further explore in this study. Also, potential markers that could predict stone recurrence will be identified, and hence earlier intervention could be offered to patients.

Efficacy of Different Modalities on Management of Renal Hard Stones

The study has been conducted in Urology department at Kafrelsheikh University Hospital between Feburary 2021 to December 2023. informed consent was taken from eligible patients and were randomized into three groups, Group A :Flexible ureteroscope (F-URS) group underwent holmium laser lithotripsy using flexible ureteroscopy (Boston® scientific (lithovue) while, Group B : extracorporeal shock wave lithotripsy (ESWL) group underwent electromagnetic extracorporeal shock wave lithotripsy (STORZ® MEDICAL Modulith SLX-F2 FD21, Germany) .Group C : Mini perc group underwent holmium laser lithotripsy using Karl® Storz MIP set.

Renal Stone Treatment Global Registry

This is an international prospective data registry to assess the treatment outcomes and complications of different treatment approaches for different surgical treatment of urolithiasis.

Multiomics Biomarkers for Urolithiasis

This is a prospective case series study. To compare urine sample of recurrent stone-formers and non-stone former by multiomics approach to identify potential markers for stone recurrence.

Acupressure as Complementary Analgesia in Shock Wave Lithotripsy

This study aims to evaluate the efficacy of acupressure applied to the LI4 (Hegu) and Qiu points before Extracorporeal Shock Wave Lithotripsy (ESWL) in patients with kidney or proximal ureteral stones. The study compares intraprocedural pain scores and procedural tolerance between an acupressure group, a sham acupressure group, and a standard care control group.

IAU Percutaneous Nephrolithotripsy Study

During the past 10-15 years, important advancements have been witnessed in percutaneous nephrolithotomy (PCNL) techniques and instrumentation. The development of miniaturized PCNL techniques and modern laser technologies has contributed to lower complication rates, alongside changes in exiting strategies and postoperative drainage protocols. Ultrasound is increasingly utilized to create percutaneous access, and many medical centers have transitioned to the supine position for PCNL or perform Endoscopic Combined Intrarenal Surgery (ECIRS). All these developments have helped to individualize treatment strategies and to improve clinical outcomes for patients. However, there remains an ongoing discussion regarding the optimal indications and limitations of the different miniaturized PCNL techniques compared to standard PCNL and retrograde intrarenal surgery (RIRS). This prospective observational study is organized under the auspices of the International Alliance of Urolithiasis (IAU) and focuses on the contemporary indications, surgical techniques, instrumentation, exiting strategies, efficacy, and risk factors for intraoperative and postoperative complications of PCNL. Participating investigators will collect data on the PCNL procedures performed in their respective clinical centers prospectively for a period of 12-18 months. The study will be initiated in each clinical center following formal approval from the IAU Scientific Committee, which will also announce the conclusion of the study.

Comparison of Two Versus Four Weeks of Ureteral Stenting Prior to Ureteroscopy After Failed Primary Ureteral Access

This study proposes a non-randomized controlled trial comparing 2 weeks versus 4 weeks of DJ ureteral stenting in patients whose primary ureteral access failed during an initial attempt at FURS. The purpose is to determine whether a longer stenting period improves subsequent ureteral access. Participants: Adults aged 18-65 years with renal/upper ureteric stones ≤20 mm and failed primary access. Sample size: 198 patients - 99 in each group. Group A: Repeat FURS after 2 weeks of DJ stenting. Group B: Repeat FURS after 4 weeks of DJ stenting. Primary outcome: Successful placement of a 10/12-Fr ureteral access sheath during repeat FURS without additional dilation. Secondary outcomes: Stone-free rate and USSQ score. Stone-free definition: No residual stone fragment ≥4 mm on NCCT at 4 weeks after FURS. Analysis: t-test/Mann-Whitney U for numerical variables and Chi-square/Fisher's exact test for categorical variables, with p \< 0.05 considered significant.

Methocarbamol vs Oxybutynin for Management of Pain and Discomfort S/P Ureteroscopy Procedure

Stone disease is a common condition, affecting approximately 9% of Americans in 2007. It causes great morbidity and is also a costly condition, estimated to cost the US healthcare system approximately 3.79 billion dollars in 2007. Ureteroscopy (URS) is the most commonly performed surgical treatment for upper tract stone disease. Ureteral stenting is a common practice after ureteroscopy and placed in \~75% of cases to prevent ureteral edema and renal obstruction. Unfortunately, ureteral stenting can be very painful and has been shown to increase the rate of emergency room visits. Many strategies have been attempted to decrease pain with ureteral stenting including modification of stent material and designs, but efforts so far have been unsuccessful in decreasing stent-related morbidity. Stent-related morbidity is hypothesized to be secondary to irritation of ureteral/bladder mucosa and muscle. Analgesics such as alpha blockers and NSAIDs have been shown to reduce stent morbidity. Anticholinergic drugs are also utilized as they decrease bladder spasms and, therefore, are hypothesized to reduce stent irritation. However, the evidence for anticholinergics has been conflicting. Anticholinergics also have a serious side effect profile including dry mouth, dry eyes, constipation, urinary retention, blurred vision, and even dementia. Some authors even hypothesize that these side effects may offset any purported benefits the anticholinergics provide for stent-morbidity. Methocarbamol is anti-spasmodic muscle relaxant that is believed to work by acting on central neurons and possibly by blocking sodium channels. Given that anticholinergics have many side effects and questionable efficacy, the investigators hypothesize that methocarbamol may achieve superior analgesia for stent morbidity and stent-related bladder spasms. Oxybutynin is used for the treatment of overactive bladder. The rationale is that the oxybutynin relaxes the muscles in the bladder to help decrease problems of urgency and frequent urination caused by the urinary stent irritation. Since anticholinergics have multiple side effects, finding an equally efficacious alternative with less side effects is highly desirable. This study will evaluate the clinical and demographic factors of patients undergoing ureteroscopy and treated postoperatively with methocarbamol vs. oxybutynin for stent-related morbidity. Additionally, the study will aim to understand the postoperative outcomes and complication rates of patients discharged with methocarbamol vs. oxybutynin after ureteroscopy with a ureteral stent in place.

Gut Oxalate Absorption in Calcium Oxalate Stone Disease

The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased absorption of dietary oxalate, which would lead to increased urinary excretion of oxalate. The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones. Participants will * ingest fixed diets containing low and moderately high amounts of oxalate for 5 days at a time * ingest a soluble form of oxalate and sugar preparations to test gut permeability * collect urine, blood, stool and breath sample during the fixed diets and the soluble oxalate test

O. Formigenes Colonization in Calcium Oxalate Kidney Stone Disease

The goal of this trial is to test if colonization with the gut bacteria Oxalobacter formigenes leads to a reduction in urinary oxalate excretion in patients with calcium oxalate kidney stone disease. The study will recruit adult participants with a history of calcium oxalate kidney stones who are not colonized with Oxalobacter formigenes. Participants will * ingest fixed diets containing low and moderately high amounts of oxalate for 4 days at a time * collect urine, blood and stool samples during the fixed diets * ingest a preparation of live Oxalobacter formigenes to induce colonization with Oxalobacter formigenes

Human Voice vs AI-Cloned Voice Audio Added to Written Consent Before Ureteroscopy or Retrograde Intrarenal Surgery (AUDIO-CONSENT)

Before kidney stone surgery with a flexible or semirigid ureteroscope, patients must read and sign a written consent form, but many patients find these forms long and hard to understand. This study tests whether listening to an audio recording of the same consent form, in addition to the usual written form and the surgeon's explanation, helps patients understand the operation better. It also asks whether it matters if the recording is read by a real urologist or produced by artificial intelligence (AI) from a clone of that same urologist's voice. Adults scheduled for their first ureteroscopy or retrograde intrarenal surgery at three hospitals in Turkey will be randomly assigned to one of three groups: (A) standard written consent only, (B) standard consent plus an audio recording read by a urologist, or (C) standard consent plus the same text produced by an AI-cloned version of the same urologist's voice. All three groups receive exactly the same information, word for word; only the way it is delivered differs. Patients in group C are told that the voice was produced by AI. The main outcome is a 10-question knowledge test on the content of the consent form, taken immediately after the consent process. Anxiety (State-Trait Anxiety Inventory) and satisfaction are also measured on the same day. No forms are completed on the day of surgery.

Tamsulosin Assisted Ureteral Access Sheath Insertion

Aim is to study if 1 week of pre operative tamsulosin would enable easier insertion of ureteral access sheath in primary retrograde intrarenal surgery for renal stone disease

Medication Facilitated Ureteral Access Sheath Deployment During Ureteroscopy: The Impact of One Week of Preoperative Tamsulosin

The goal of this clinical trial is to assess whether tamsulosin given one week prior to renal or ureteric stone surgery would improve the success rate of ureteral access sheath deployment and decrease ureteral injury

Assessment of Urinary Microplastic Concentration in Patients With Urolithiasis: A Prospective Case-Control Study

This prospective observational case-control study aims to evaluate the presence and burden of microplastic particles in urine samples from patients with kidney and ureteral stones and to compare these findings with healthy controls. The study will also investigate the associations between urinary microplastic burden and clinical characteristics of urinary stone disease, including stone size, stone density measured in Hounsfield units (HU), localization, and stone composition.

Real-World Study of Obstructive Upper Urinary Tract Stones and Acute Pyelonephritis

Upper urinary tract stone obstruction complicated by acute pyelonephritis is a critical urological emergency requiring urgent decompression and infection control, yet real-world clinical decisions regarding the choice between retrograde ureteral stenting, percutaneous nephrostomy, or initial antibiotic therapy often vary based on physician experience and resource availability. This prospective, multi-center, observational study aims to enroll 1,650 patients across more than 30 hospitals in China to systematically evaluate the technical success rates, infection control efficacy, and safety profiles of these different management strategies. By analyzing natural clinical cohorts without intervening in routine practice, the study seeks to define the optimal application boundaries for retrograde stenting, evaluate the role of nephrostomy as a primary or salvage treatment, and establish risk models to predict the failure of conservative antibiotic therapy, ultimately providing high-level evidence for individualized and precise clinical decision-making.

Transurethral Versus Percutaneous Cystolithotripsy for Bladder Stones in Adults

This study evaluates and compares two minimally invasive surgical approaches for treating bladder stones in adult patients: transurethral cystolithotripsy (TUCL) and percutaneous cystolithotripsy (PCCL). Urinary bladder stones are commonly managed using endoscopic techniques to avoid the morbidity of open surgery. TUCL accesses the bladder through the natural urinary channel (urethra), whereas PCCL accesses the bladder directly through a small puncture in the lower abdomen above the pubic bone. While both approaches are effective, comparative data in adult populations remain limited. Eligible participants are randomly assigned to receive either TUCL or PCCL. The primary goal is to compare stone clearance rates and operative times between the two procedures. Secondary objectives include comparing surgical complication rates, duration of postoperative urinary catheterization, and length of hospital stay.

Endogenous Oxalate Synthesis in Idiopathic Calcium Oxalate Kidney Stone Disease

The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased production of oxalate by the body, which would lead to increased urinary excretion of oxalate. The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones. Participants will ingest fixed diets containing low amounts of oxalate for 5 days ingest a soluble form of glycolate and vitamin C collect urine, blood, stool during the dietary and oral dosing portions of the study and also collect breath sample during the oral glycolate test

A Study on the Application of NE Irrigation Fluid for Hemostasis in Flexible Ureteroscopic Lithotripsy: A Prospective Single-arm Interventional Study of Upper Urinary Tract Calculi.(NE: Norepinephrine)

Urinary stone disease is globally prevalent with rising incidence and recurrence, imposing heavy socioeconomic burdens. Flexible ureteroscopy has advanced stone treatment. Single-use flexible ureteroscopes (su-fURS) combined with negative pressure ureteral access sheath (NPUAS), recommended by urology guidelines, improve surgical safety and stone-free rates and can treat stones ≤3 cm. However, su-fURS has poorer image quality, bleeding during lithotripsy may blur vision, frequently impairing efficiency and safety. Norepinephrine (NE), a tyrosine-derived sympathomimetic amine, mainly activates α1 and β1 receptors. Doses above 3 μg/min trigger predominant α1-mediated vasoconstriction of arteries and veins. It can act on mucosal surfaces via irrigation fluid, making it favorable for initial hemostasis of injured mucosa. Firstly, this study aims to evaluate the efficacy and safety of low-concentration norepinephrine (NE) irrigation solution for hemostasis during lithotripsy performed with single-use flexible ureteroscope (su-fURS) combined with NPUAS, fifteen subjects will be enrolled in the study. Secondly, we explore the dose-effect relationships of four concentrations: 2 mg/3 L, 4 mg/3 L, 6 mg/3 L and 8 mg/3 L, and determine the optimal concentration by comprehensively evaluating hemostatic efficacy and safety. A total of 40 subjects will be enrolled, with 10 subjects in each concentration.

Comparing Efficiency and Stone-Free Rates Mini PCNL vs Flex URS

The objective of the study is to compare the stone free rates with ureteroscopy utilizing the ClearPETRA suction ureteral access sheath, and mini-PCNL; both procedures and ClearPETRA sheaths are standard of care and are used regularly for stone treatment. Our primary objective is to assess the complete stone free rate with both procedures.

Long-term Safety of UAS-assisted vs Sheathless RIRS in Non-prestented Patients

This retrospective comparative cohort study will include adult patients who underwent primary RIRS for renal stones ≤20 mm at Al-Azhar University Hospitals between January 2020 and December 2025. Patients will be classified by whether a ureteral access sheath (UAS) was used during the index RIRS, and all eligible patients will be invited for active long-term follow-up (minimum 12 months) to assess the composite outcome of delayed ipsilateral ureteral stricture or new/progressive ipsilateral hydronephrosis and other safety and efficacy outcomes. Propensity-score methods and adjusted regression analyses will be used to control confounding.