Clinical Research Directory

Modified Mini-PCNL Versus Standard PCNL for Complex Kidney Stones

Kidney stones that are large or complex are often treated with percutaneous nephrolithotomy, also called PCNL. Standard PCNL uses a larger access tract and is effective for removing complex kidney stones, but it may be associated with more bleeding, pain, and recovery burden. Modified mini-PCNL uses a smaller access tract and may reduce surgical trauma while maintaining a similar stone clearance rate. This multicenter randomized trial will compare modified mini-PCNL using a 20 Fr access sheath with standard PCNL using a 24 Fr access sheath in adults with complex renal stones. About 1,380 participants from 8 urology centers will be randomly assigned to receive one of the two procedures. The main purpose of the study is to determine whether modified mini-PCNL is not worse than standard PCNL in achieving stone-free status shortly after surgery. Stone-free status will be assessed by low-dose noncontrast CT within 72 hours after surgery. The study will also compare stone-free status at 3 months, complications, operation time, length of hospital stay, need for additional procedures, and quality of life.

Thulium Fiber Laser (TFL) vs Thulio Pulsed Thulium:YAG (p-Tm:YAG)

This research study is being conducted to assess the ability and efficiency of two laser systems to break up kidney stones during ureteroscopy with laser lithotripsy for kidney stone treatment.

Comparison of Vacuum-Assisted and Conventional Ureteral Access Sheath in Retrograde Intrarenal Surgery

This study aims to compare the efficacy and safety, the ratio of stone-free rates, and complications of two types of access sheaths used in retrograde intrarenal surgery to treat upper urothelial stones. The access sheath types are those with vacuum aspiration and the conventional ones.

The Effect of Apple Cider Vinegar Supplementation on 24-hour Urine Chemistry in Adults

This is a single-center prospective cohort study to evaluate the effect of short-term daily apple cider vinegar (ACV) supplementation on urine chemistry.

Flexible Ureteroscopy With a Flexible and Navigable Suction Ureteral Access Sheath Versus Mini-Percutaneous Nephrolithotomy for 1-2 cm Lower Pole Kidney Stones

This study, known as the FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy), is an international, multicenter, randomized, non-inferiority trial. It aims to compare the effectiveness and safety of flexible ureteroscopy using a flexible and navigable suction ureteral access sheath (FANS) versus mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole kidney stones. A total of 640 eligible adult patients will be enrolled across 20 high-volume urology centers in China, Russia, Turkey, and India. Participants will be randomly assigned to undergo either FANS-assisted flexible ureteroscopy or mini-PCNL. The primary outcome is the immediate stone-free rate (SFR) assessed by non-contrast CT within 72 hours after surgery. Secondary outcomes include SFR at 1 month, operative time, pain score, length of hospital stay, complication rates, and changes in health-related quality of life. The goal of this trial is to determine whether the less invasive FANS-assisted approach is non-inferior to mini-PCNL in terms of efficacy, while potentially offering advantages in postoperative recovery and safety.

PMCF Investigation of MODULITH® SLX-F2 With StorM-Track in Patients With Kidney Stones

Extracorporeal shockwave lithotripsy (ESWL) is a non-invasive standard treatment for kidney stones. This study will be conducted to evaluate the effectiveness of ESWL using MODULITH® SLX-F2 with stone tracking, compared to MODULITH® SLX-F2 without stone tracking, in adult patients with kidney stones, as measured by stone-free status.

Flexible and Navigable Suction Ureteral Access Sheath (FANS) vs Conventional Access Sheaths in RIRS: A Prospective Randomized Study.

Kidney stones located in the kidney are commonly treated using a minimally invasive procedure called retrograde intrarenal surgery (RIRS). During this procedure, a ureteral access sheath is often used to facilitate repeated access to the kidney, improve visualization, and allow irrigation fluid to drain. Newer access sheaths have been developed with flexible distal tips and built-in suction capabilities, which may help reduce operative time by improving visibility and removing stone fragments and irrigation fluid more efficiently. This prospective randomized study compared a flexible and navigable suction ureteral access sheath with a conventional ureteral access sheath in adult patients undergoing RIRS for kidney stones measuring 10 mm or larger. Participants were randomly assigned to one of the two access sheath types. The primary objective of the study was to evaluate whether the use of a suction-enabled access sheath reduces operative time. Secondary objectives included assessment of complications, length of hospital stay, stone-free rate, and need for additional interventions.

Transient Apnea During Flexible Ureteroscopic Lithotripsy

Respiration-related renal motion may reduce targeting stability during flexible ureteroscopic laser lithotripsy and thereby decrease lithotripsy efficiency. This single-center, three-arm randomized controlled trial evaluated whether transient apnea during active lithotripsy could improve lithotripsy efficiency while maintaining short-term physiologic safety. A total of 150 patients undergoing flexible ureteroscopic lithotripsy for renal stones were randomized in a 1:1:1 ratio to regular mechanical ventilation, small tidal-volume ventilation, or transient apnea. The primary outcome was active lithotripsy efficiency, defined as CT-based stone volume divided by active lithotripsy time. Physiologic safety was assessed using serial arterial blood gas measurements at baseline, 3, 6, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation, together with continuous intraoperative cardiopulmonary monitoring.

Empiric Versus Selective Prevention Strategies for Kidney Stone Disease

The aims of this study are to 1) Conduct a randomized clinical trial of selective versus empiric diet plus pharmacologic therapy in high-risk stone formers and 2) Determine adverse effects from, and adherence to selective and empiric strategies.

Safety and Effectiveness of the Ultrasonic Propulsion of Kidney Stones

This study tests moving kidney stones using focused ultrasound (referred to as ultrasonic propulsion). The study includes multiple population groups to investigate the ability of our technology to: a) move stone fragments to a location within the kidney to improve their chances of passage, and thus reduce the occurrence of additional symptomatic events and retreatment or b) move a symptomatic stone to relieve symptoms and pain.

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

Evaluation of Eye Gaze Sharing in the Operating Room

This project aims to develop an augmented reality (AR) tool to enhance skill acquisition for endoscopic kidney stone surgery. Of the 100,000 patients who undergo an endoscopic kidney stone treatment annually in the United States, 25% will require a repeat stone surgery within 20 months of their index surgery. The repeat stone surgery rate is almost completely driven by postoperative residual stone fragments, which lead to ureteral obstruction, causing pain, urinary tract infection, and kidney injury. One significant factor that contributes to residual stone fragments is limited visualization of the entire collecting system - a skill directly associated with surgeon experience. This leads to novice surgeons having a much higher recurrence rate than experienced ones. As the incidence of kidney stone disease continues to increase (prevalence of 10%, incidence of 1116 per 100,000), improved endoscopic surgical training is required to improve outcomes of stone surgeries and minimize complications by improving stone-free rate. Currently, skill assessment during endoscopic stone surgery is limited. There are no objective metrics for endoscopic surgery to assess skill. The only feedback trainees get is in the form of verbal communication from expert surgeons, usually after the conclusion of surgery. Thus, most feedback is synoptic and limited in facilitating skill acquisition. Operative time and patient safety concerns restrict the amount of active, real-time feedback given during a case for skill acquisition. Endoscopic kidney stone surgery is uniquely challenging given the small depth and field of view of current endoscopes, which complicate the complete visualization of the entire collecting system. Navigation of the collecting system relies on mentally mapping preoperative imaging to the endoscopic surgical field. Success in mapping relies on hand-eye coordination, memory, and spatial reasoning, which are gained through practice. Thus, there is a need for tools that facilitate endoscopic surgical skill acquisition. The overarching hypothesis for this research is that surgical skill acquisition and outcomes for endoscopic kidney stone surgery can be improved by analyzing eye gaze data and using expert gaze to guide surgical trainees intraoperatively. Eye gaze guidance has been shown to lead to better skill acquisition in virtual reality surgical tasks compared with motion guidance alone. The proposed system would provide real-time education for trainees during endoscopic stone surgery, such as through head-mounted displays (i.e., the Microsoft HoloLens 2). The investigators have previously demonstrated eye gaze sharing in phantoms. By implementing this system in the operating room (OR), the investigators would be able to instill durable skill acquisition in trainees. The investigators will also implement the NASA-task load index for the trainees to gauge the usability of the system.

Eye Gaze Guidance Evaluation in Phantoms

This project aims to develop an augmented reality (AR) tool to enhance skill acquisition for endoscopic kidney stone surgery. Of the 100,000 patients who undergo an endoscopic kidney stone treatment annually in the United States, 25% will require a repeat stone surgery within 20 months of their index surgery. The repeat stone surgery rate is almost completely driven by postoperative residual stone fragments, which lead to ureteral obstruction, causing pain, urinary tract infection, and kidney injury. One significant factor that contributes to residual stone fragments is limited visualization of the entire collecting system - a skill directly associated with surgeon experience. This leads to novice surgeons having a much higher recurrence rate than experienced ones. As the incidence of kidney stone disease continues to increase (prevalence of 10%, incidence of 1116 per 100,000), improved endoscopic surgical training is required to improve outcomes of stone surgeries and minimize complications by improving stone-free rate. Currently, skill assessment during endoscopic stone surgery is limited. There are no objective metrics for endoscopic surgery to assess skill. The only feedback trainees get is in the form of verbal communication from expert surgeons, usually after the conclusion of surgery. Thus, most feedback is synoptic and limited in facilitating skill acquisition. Operative time and patient safety concerns restrict the amount of active, real-time feedback given during a case for skill acquisition. Endoscopic kidney stone surgery is uniquely challenging given the small depth and field of view of current endoscopes, which complicate the complete visualization of the entire collecting system. Navigation of the collecting system relies on mentally mapping preoperative imaging to the endoscopic surgical field. Success in mapping relies on hand-eye coordination, memory, and spatial reasoning, which are gained through practice. Thus, there is a need for tools that facilitate endoscopic surgical skill acquisition. The overarching hypothesis for this research is that surgical skill acquisition and outcomes for endoscopic kidney stone surgery can be improved by analyzing eye gaze data and using expert gaze to guide surgical trainees intraoperatively. Eye gaze guidance has been shown to lead to better skill acquisition in virtual reality surgical tasks compared with motion guidance alone. The proposed system would provide real-time education for trainees during endoscopic stone surgery, such as through head-mounted displays (i.e., the Microsoft HoloLens 2). The investigators have previously demonstrated eye gaze sharing in phantoms. By implementing this system in the operating room (OR), the investigators would be able to instill durable skill acquisition in trainees.

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.

Oxalate-Driven Host Responses in Kidney Stone Disease

This study is looking to understand the role of oxalate on kidney stone development and immunity. This study will enroll healthy participants and participants with calcium oxalate kidney stones (CaOx KS). Participants will be in this study for about 3 weeks, consume controlled diets, and provide blood and urine specimens.

Acoustic Impedance Matching in ESWL Coupling

The purpose of this study is to investigate the effect of different salt concentrations (tonicity) in the coupling fluid used during Extracorporeal Shock Wave Lithotripsy (ESWL). The study compares three types of coupling fluids: hypotonic (degassed water), isotonic (0.9% NaCl), and hypertonic (3% NaCl) solutions. Researchers aim to determine which solution provides the best stone fragmentation success while minimizing procedure-related pain and skin complications.

Surgical Outcomes and Costs in Using the Shenzhen HugeMed 6.3 French Flexible Ureteroscope

Comprehensive comparative investigations between HugeMed HU30M 6.3 Fr f-URS and traditional approach f-URS devices in RIRS are lacking in an American population. The investigators aim to compare the outcomes of using the 6.3 Fr f-URS versus traditional approach (other f-URS present in our institution) to treat patients with stone burden ≤ 2.5 cm. The findings of this study will expand on the potential advantages and drawbacks of HU30M in enhancing surgical outcomes and patient safety in RIRS procedures. We hypothesize that the use of the HU30M will result in increased cost savings while providing similar stone free rates when compared to traditionally used f-URS devices.

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.

Effect of Complete Suction-Induced Collapse of the Renal Collecting System at the End of RIRS on Early Postoperative Outcomes

The purpose of this study is to evaluate whether actively suctioning the renal collecting system to induce a "collapse" state at the end of retrograde intrarenal surgery (RIRS) can reduce postoperative pain and infection in patients with kidney stones. Participants will be randomly assigned to either the experimental group (suction-induced collapse) or the control group (standard drainage). The study aims to determine if this simple surgical modification can improve early recovery outcomes and patient satisfaction.

FANS-Assisted Mini-PCNL for Complex Renal Stones

This prospective pilot study aims to evaluate the feasibility, safety, and preliminary clinical outcomes of a novel mini-percutaneous nephrolithotomy (mini-PCNL) technique integrating a flexible mini-nephroscope with a flexible and navigable suction access sheath (FANS) for the treatment of complex renal stones. Thirty consecutive patients with renal stones ≥2 cm will be prospectively enrolled. All patients will undergo FANS-assisted mini-PCNL. The primary outcome is the immediate stone-free rate assessed by non-contrast CT within 72 hours after surgery. Secondary outcomes include operative parameters, postoperative pain, complications, length of hospital stay, and quality of life. This pilot study is designed to provide preliminary evidence supporting the feasibility and safety of FANS-assisted mini-PCNL and to inform the design of future larger-scale studies.

Pain Control During ESWL Using Non-Opioid Analgesics

This prospective randomized controlled trial aims to compare the analgesic efficacy of three non-opioid analgesics (ibuprofen, paracetamol, and tenoxicam) during extracorporeal shock wave lithotripsy (ESWL). All patients undergoing ESWL will be randomly assigned into four groups including a placebo group. Pain intensity will be assessed using the Visual Analog Scale (VAS) at the 5th, 10th, 15th, and 20th minutes during the procedure. In addition to comparing analgesic efficacy, the study will evaluate patient-related and stone-related factors affecting pain perception, including body mass index, subcutaneous fat thickness, and stone density measured by Hounsfield Units. The study also aims to assess the relationship between analgesic efficacy, energy levels applied during ESWL, and treatment outcomes such as stone-free rates. The findings may contribute to optimizing individualized pain management strategies and improving treatment efficiency in ESWL procedures.

DISS vs FANS in Suction-Assisted RIRS for Medium-Sized Renal Stones

Kidney stones are a common health problem and may recur frequently, which can affect quality of life and kidney function. Retrograde intrarenal surgery (RIRS) is a minimally invasive treatment used for renal stones, but treatment of medium-sized stones may be associated with longer operative time, impaired visibility during surgery, residual stone fragments, and postoperative infectious complications caused by increased intrarenal pressure. Suction-assisted retrograde intrarenal surgery (RIRS) techniques have been developed to improve surgical efficiency and safety by facilitating continuous removal of stone fragments and helping control intrarenal pressure. Two commonly used suction-assisted approaches are direct in-scope suction (DISS) and flexible and navigable suction ureteric access sheath (FANS). However, there is limited prospective randomized evidence directly comparing these two techniques. This randomized prospective clinical study aims to compare direct in-scope suction (DISS) versus flexible and navigable suction ureteric access sheath (FANS) in adult patients with medium-sized renal stones measuring 2 to 3 cm who are undergoing retrograde intrarenal surgery (RIRS). Participants will be randomly assigned to one of the two suction-assisted techniques. The study will evaluate whether flexible and navigable suction ureteric access sheath (FANS) provides better outcomes than direct in-scope suction (DISS) in terms of stone-free rate and postoperative infection rate. The primary outcome is stone-free status assessed by postoperative imaging. Secondary outcomes include operative time, intraoperative visibility, and postoperative complications, particularly infection and urosepsis. The study hypothesis is that suction-assisted retrograde intrarenal surgery (RIRS) using the flexible and navigable suction ureteric access sheath (FANS) technique will result in a higher stone-free rate and a lower postoperative infection rate compared with direct in-scope suction (DISS) in the management of medium-sized renal stones.

Pilot Study of Patient Navigation for Kidney Stone Patients After ED Visits

Patients who visit the emergency department for kidney stones are sometimes referred to urology for follow-up care but never complete that visit. Missing follow-up appointments can lead to worse outcomes, including recurrent pain, infection, or surgery. Research shows that patients who are socially or economically at risk (such as those with public insurance, lower income, or limited English proficiency) are more likely to experience these care gaps. This study will pilot a patient navigation program designed to help patients with urinary stone disease (USD) attend their scheduled urology appointments after being seen in the Emergency Department. Using an electronic health record (EHR) based prediction model developed in earlier research, patients at higher risk for being lost to follow-up will be identified and invited to participate. Each participant will be paired with a trained patient navigator who will assess barriers to care, provide support, and maintain contact for about 12 weeks. The goal of this study is to evaluate the outcomes and feasibility of this navigation intervention. Findings will help determine whether a larger study should test if this approach improves access to care and health outcomes for patients with kidney stones.

FANS vs CVAC for Medium to Large Stones

Improvements in ureteroscopes have led to improved stone free rates. Two new devices (FANS - Flexible and Navigable Suction) and the CVAC ureteroscope have never been compared head to head. This trial will compare these two new suction ureteroscope technologies against each other