Flexible Ureteroscopy for Renal Calculi: Technique Optimization and Complication Management

Introduction

Flexible ureteroscopy (fURS) has emerged as a cornerstone in the management of renal calculi, offering a minimally invasive approach for treating stones located throughout the upper urinary tract. Its evolution from rigid ureteroscopy represents a significant technological leap, enabling access to complex intrarenal anatomy with reduced patient morbidity compared to traditional percutaneous nephrolithotomy (PCNL) or shock wave lithotripsy (SWL) in certain scenarios. The ability to directly visualize and treat stones within the renal collecting system, combined with advancements in laser lithotripsy and basketing technologies, has solidified fURS as a primary treatment modality for a wide range of kidney stone sizes and locations.

The increasing adoption of fURS is driven by several factors, including improved stone-free rates for specific stone burdens, shorter hospital stays, faster recovery times, and the ability to treat patients who may not be suitable candidates for other modalities (e.g., patients on anticoagulation, those with complex anatomy, or individuals with radiolucent stones). However, the success of fURS is highly dependent on meticulous technique, appropriate patient selection, sophisticated instrumentation, and effective management of potential complications.

This comprehensive review delves into the intricacies of flexible ureteroscopy for renal calculi, focusing on optimizing surgical techniques and navigating potential complications. We will explore the evolution of flexible ureteroscopes, advancements in ancillary equipment such as access sheaths and guidewires, laser lithotripsy principles, stone extraction strategies, and perioperative management protocols. Furthermore, we will provide a detailed overview of common and rare complications associated with fURS, discussing their prevention, recognition, and management based on current evidence and expert consensus.

By synthesizing the latest literature and clinical insights, this article aims to equip urologists, residents, and fellows with the knowledge necessary to enhance their fURS proficiency. The goal is to provide practical guidance on technique optimization, patient safety, and complication management, ultimately improving clinical outcomes for patients undergoing flexible ureteroscopy for the treatment of renal calculi in 2025 and beyond.

Evolution and Technology of Flexible Ureteroscopes

Historical Development

Tracing the path to modern fURS:

1. Early rigid ureteroscopy (1970s-1980s): Limited to distal ureter, significant morbidity.
2. First-generation flexible ureteroscopes (late 1980s-1990s): Fiberoptic imaging, limited deflection, poor durability, passive secondary deflection.
3. Second-generation instruments (late 1990s-2000s): Improved fiberoptics, active secondary deflection, enhanced durability, smaller diameters.
4. Digital flexible ureteroscopes (mid-2000s onwards): Chip-on-tip technology, superior image quality (resolution, brightness, field of view), elimination of honeycomb effect, improved ergonomics.
5. Single-use flexible ureteroscopes (2010s onwards): Addressing durability and reprocessing concerns, consistent performance, cost considerations, environmental impact debate.

Current Flexible Ureteroscope Technology

Key features of modern instruments:

1. Digital Imaging Systems:
   • CMOS or CCD sensors at the tip.
   • High-definition (HD) and potentially 4K resolution.
   • Enhanced illumination (LED vs. Xenon).
   • Wider field of view (e.g., 90-120 degrees).
   • Image processing capabilities (e.g., Narrow Band Imaging – NBI, Storz Professional Image Enhancement System – SPIES).
2. Deflection Mechanisms:
   • Primary active deflection (typically 270-280 degrees up/down).
   • Secondary active deflection (available on some models).
   • Importance of dual deflection for lower pole access.
   • Deflection durability and maintenance.
3. Canal de travail:
   • Standard size: 3.6 French (Fr).
   • Allows passage of laser fibers (200-365 µm), baskets (1.5-3 Fr), guidewires, and irrigation.
   • Impact of instruments on irrigation flow and deflection capability.
   • Larger channel options in some models.
4. Outer Diameter:
   • Typically ranges from 7.5 Fr to 9.9 Fr.
   • Smaller diameters facilitate access without aggressive dilation.
   • Balance between diameter, channel size, and durability.
5. Durability and Maintenance:
   • Major challenge for reusable scopes.
   • Common failure points: deflection mechanism, working channel, fiberoptics/chip.
   • Impact of laser energy, torqueing, and handling.
   • Repair costs and turnaround times.

Single-Use vs. Reusable Flexible Ureteroscopes

Comparing the two paradigms:

1. Advantages of Single-Use Scopes:
   • Eliminates reprocessing costs and potential cross-contamination risk.
   • Guaranteed performance and image quality for every case.
   • No repair costs or downtime.
   • Potentially lighter weight and improved ergonomics in some models.
   • Availability for emergent cases.
2. Advantages of Reusable Scopes:
   • Lower per-case cost after initial investment (depending on usage volume and repair rates).
   • Potentially superior image quality and durability in high-end models.
   • Familiarity for experienced surgeons.
   • Reduced environmental waste compared to single-use plastics (though reprocessing also has environmental impact).
3. Cost-Effectiveness Analysis:
   • Highly dependent on case volume, repair frequency/cost, reprocessing efficiency, and purchase price.
   • Break-even point calculations vary significantly.
   • Studies show conflicting results based on local factors.
4. Performance Comparison:
   • Early single-use models had limitations in image quality and deflection.
   • Newer generations are increasingly comparable to reusable digital scopes.
   • Objective comparisons are ongoing.
5. Clinical Decision Factors:
   • Institutional budget and resources.
   • Case volume and complexity.
   • Reprocessing capabilities and quality control.
   • Surgeon preference and experience.
   • Infection control priorities.

Preoperative Preparation and Patient Selection

Évaluation des patients

Essential steps before fURS:

1. Medical History: Comorbidities (cardiac, pulmonary, renal), anticoagulation/antiplatelet use, history of urinary tract infections (UTIs), previous stone surgeries, allergies.
2. Stone Characteristics:
   • Imaging (Non-contrast CT is gold standard): Size, number, location (especially lower pole vs. other calyces), density (Hounsfield Units – HU).
   • Stone composition history (if known).
   • Impacted stones.
3. Anatomical Assessment:
   • Collecting system anatomy (infundibular length/width, pelvic anatomy, calyceal orientation, lower pole angle – infundibulopelvic angle).
   • Ureteral anatomy (strictures, tortuosity, previous ureteral surgery).
   • Presence of hydronephrosis.
   • Congenital anomalies (horseshoe kidney, pelvic kidney, duplicated system).
4. Urinalysis and Urine Culture: Mandatory to detect and treat pre-existing UTI. Sterile urine is required before elective fURS.
5. Renal Function Assessment: Serum creatinine, estimated glomerular filtration rate (eGFR).

Indications for fURS

Appropriate scenarios for the procedure:

1. Renal Stones:
   • Stones < 2 cm in size (primary indication).
   • Lower pole stones < 1.5 cm (especially with favorable anatomy).
   • Multiple renal stones.
   • Stones resistant to SWL.
   • Stones in patients where SWL is contraindicated (obesity, bleeding diathesis, pregnancy – relative contraindication).
   • Radiolucent stones not visible on fluoroscopy.
   • Stones in anomalous kidneys (horseshoe, pelvic).
2. Ureteral Stones:
   • Proximal ureteral stones (alternative to SWL or antegrade approaches).
   • Impacted proximal stones.
   • Stones associated with distal strictures (requiring simultaneous treatment).
3. Diagnostic Ureteroscopy: Evaluation of hematuria, abnormal imaging findings, positive cytology, surveillance for upper tract urothelial carcinoma (UTUC).
4. Adjunctive Role: Treatment of residual fragments after PCNL or SWL.

Contre-indications

When fURS should be avoided or used with caution:

1. Contre-indications absolues:
   • Untreated UTI.
   • Medical instability precluding anesthesia.
2. Contre-indications relatives:
   • Severe uncorrected coagulopathy.
   • Large stone burden (> 2 cm) – PCNL often preferred, though staged fURS is an option.
   • Complex anatomy making access impossible (severe strictures, impassable tortuosity).
   • Pregnancy (requires careful consideration, often deferred if possible).
   • Inability to achieve lithotomy positioning.

Preoperative Optimization

Maximizing safety and success:

1. Anticoagulation Management: Consultation with prescribing physician, bridging therapy if necessary, timing of cessation and resumption based on guidelines (e.g., AUA guidelines).
2. Prophylaxie antibiotique: Administered within 60 minutes prior to incision/scope insertion, based on local antibiogram and patient risk factors (e.g., history of UTI, positive preoperative culture, stent presence).
3. Pre-stenting: Controversial. May be considered in cases of tight ureter, impacted stones, or planned staged procedures to facilitate ureteral access and potentially reduce intraoperative pressure. However, it adds another procedure and potential morbidity (stent discomfort, infection risk).
4. Patient Counseling: Detailed discussion of risks, benefits, alternatives, expected outcomes (stone-free rates), potential need for staged procedures, postoperative stent placement, and recovery process.

Surgical Technique Optimization

Anesthésie et positionnement

Setting the stage for the procedure:

1. Anesthésie: General anesthesia is standard, allowing for controlled respiration and patient immobility.
2. Positionnement: Dorsal lithotomy position with legs in stirrups (e.g., Allen stirrups, Yellow Fin stirrups). Ensure adequate padding to prevent nerve injury (peroneal nerve) and compartment syndrome. Slight Trendelenburg may aid upper ureteral access.

Cystoscopy and Initial Ureteral Access

Navigating the lower urinary tract:

1. Cystoscopy: Initial inspection of bladder, identification of ureteral orifices.
2. Guidewire Placement:
   • Placement of a safety guidewire into the renal pelvis under fluoroscopic guidance is crucial before any ureteral manipulation.
   • Choice of guidewire (standard PTFE-coated, hydrophilic, stiff shaft, nitinol core) depends on anatomy and surgeon preference.
   • A second working guidewire may be placed alongside the safety wire if ureteral access sheath (UAS) placement is planned.
3. Retrograde Pyelogram (Optional): May be performed to delineate ureteral and renal pelvic anatomy if not clearly defined on preoperative imaging, especially if strictures are suspected.

Ureteral Access Sheath (UAS)

Facilitating scope passage and reducing pressure:

1. Rationale: Protects the ureter from trauma during multiple scope passages, maintains lower intrarenal pressures by allowing irrigation outflow, facilitates fragment removal.
2. Sizing: Typically 10/12 Fr to 14/16 Fr outer diameter. Choice depends on ureteral caliber and scope size. Smaller sizes minimize ureteral trauma risk.
3. Placement Technique: Passed over a working guidewire, often requiring sequential dilation if the ureter is narrow. Fluoroscopic guidance is essential.
4. Indications: Generally recommended for most fURS cases involving significant stone work, multiple scope insertions, or prolonged procedures.
5. Potential Complications: Ureteral wall ischemia, perforation, stricture formation (especially with prolonged use or oversized sheaths). Risk minimized by using the smallest effective size and limiting duration.
6. Sheathless fURS: An option in select cases (small stone burden, short procedure time, dilated ureter) to minimize ureteral trauma, but may increase intrarenal pressure and make fragment extraction harder.

Flexible Ureteroscope Insertion and Navigation

Reaching the target stone:

1. Scope Preparation: White balancing, focus adjustment, checking deflection mechanism.
2. Insertion: Advanced over the working guidewire (or through the UAS). Gentle technique is paramount. Avoid forcing the scope.
3. Navigation: Systematic inspection of the entire collecting system. Use fluoroscopy intermittently to confirm location and orientation. Utilize scope deflection and torque to navigate calyces. Lower pole access may require maximal dual deflection and specific maneuvers (e.g., rotating the scope).
4. Gestion de l'irrigation:
   • Use saline or sterile water.
   • Gravity irrigation is preferred over pressure bags or pumps to minimize intrarenal pressure (< 30-40 mmHg is ideal).
   • Ensure adequate outflow (especially when using a UAS).
   • Maintain clear visualization.

Laser Lithotripsy Techniques

Breaking the stone:

1. Laser Technology: Holmium:YAG (Ho:YAG) laser is the gold standard. Thulium fiber laser (TFL) is an emerging alternative with potential advantages (smaller fiber size, different fragmentation properties).
2. Laser Fiber Selection:
   • Size: 200-365 µm typically used. Smaller fibers (200-275 µm) offer greater scope deflection and irrigation flow but are more fragile and deliver less energy density.
   • Reusable vs. single-use fibers.
3. Laser Settings:
   • Energy (Joules): Typically 0.2 J to 2.0 J.
   • Frequency (Hertz): Typically 5 Hz to 80 Hz.
   • Pulse Duration (long vs. short): Affects fragmentation vs. dusting.
   • Settings are adjusted based on technique (dusting vs. fragmentation) and stone composition.
4. Fragmentation Technique: Using higher energy (e.g., 0.8-1.5 J) and lower frequency (e.g., 5-15 Hz) to break the stone into pieces suitable for basket extraction.
5. Dusting Technique: Using lower energy (e.g., 0.2-0.5 J) and higher frequency (e.g., 30-80 Hz), often with long pulse duration, to ablate the stone into fine particles (< 1-2 mm) expected to pass spontaneously. Requires meticulous technique to avoid fragment migration.
6. Popcorn/Pop-dusting Technique: Using high frequency and energy in a contained space (e.g., lower calyx) to fragment stones via cavitation bubbles and particle collisions.
7. Safety Precautions:
   • Always visualize the fiber tip before firing.
   • Keep fiber tip 1-2 mm away from urothelium.
   • Avoid firing directly onto baskets or guidewires.
   • Use laser safety eyewear.
   • Ensure fiber is not advanced beyond the scope tip when deflecting.

Stone Extraction Techniques (Basketing)

Removing fragments:

1. Basket Types: Nitinol wire baskets are standard. Various designs exist (tipless, flat wire, helical, multi-wire), sizes typically 1.5 Fr to 3 Fr.
2. Technique:
   • Basket deployed beyond the fragment.
   • Opened and gently maneuvered to capture the fragment.
   • Closed carefully, ensuring no urothelial entrapment.
   • Entire scope (or scope through UAS) withdrawn with the basket and fragment.
   • Avoid pulling large fragments through a narrow ureter or UAS.
3. Indications: Used primarily with fragmentation technique, or for larger residual fragments after dusting.
4. Challenges: Difficult capture in dilated systems, potential for urothelial trauma, basket entrapment (rare).

Completion and Exit Strategy

Concluding the procedure:

1. Inspection finale: Thorough re-inspection of the entire collecting system to ensure adequate fragmentation/clearance and identify any potential injury.
2. Scope Removal: Gentle withdrawal over the safety guidewire.
3. Ureteral Stent Placement:
   • Indications: Prolonged procedure, significant stone burden treated, ureteral trauma (instrumentation difficulty, edema, minor perforation), solitary kidney, planned second-look procedure, significant residual fragments.
   • Routine stenting is debated, but often performed to prevent postoperative obstruction from edema or fragments.
   • Stent size (e.g., 4.7-6 Fr) and length selected based on ureteral length (measured or estimated).
   • Placement over the safety guidewire.
   • Consideration of tethered stents for easier office removal.
4. Foley Catheter: May be placed temporarily, especially if significant bladder irrigation occurred or if hematuria is anticipated.

Gestion des complications

Complications peropératoires

Challenges during the procedure:

1. Failure to Access Ureter/Kidney:
   • Causes: Tight orifice, stricture, tortuosity, large prostate.
   • Management: Guidewire manipulation, hydrophilic wires, ureteral dilation (balloon or sequential), consider pre-stenting and rescheduling, abandon procedure if unsafe.
2. Guidewire Malposition/Loss:
   • Prevention: Secure wire externally, careful scope/sheath passage.
   • Management: Attempt re-passage under fluoroscopy, use second wire, abandon if safety wire cannot be maintained/re-established.
3. Ureteral Perforation:
   • Causes: Guidewire trauma, forceful scope/sheath insertion, laser injury.
   • Recognition: Extravasation on fluoroscopy, direct visualization.
   • Management: Minor perforations often managed with prolonged stenting (4-6 weeks). Larger perforations may require abandoning the procedure and stenting, or rarely, open/laparoscopic repair. Avoid high-pressure irrigation.
4. Bleeding:
   • Causes: Mucosal trauma, laser injury, avulsion.
   • Management: Usually minor and controlled by tamponade effect of scope/sheath or reduced irrigation pressure. Persistent significant bleeding is rare but may require coagulation (laser on low setting, cautiously) or abandoning the procedure.
5. Laser-Related Complications:
   • Urothelial injury/burn: Avoid direct contact, use appropriate settings.
   • Fiber breakage: Remove fragments immediately.
   • Scope damage: Avoid firing when fiber tip is retracted or against scope.
6. Instrument Malfunction:
   • Scope failure (optics, deflection): Switch to backup scope (reusable or single-use).
   • Basket entrapment/breakage: Complex; may require specialized endoscopic tools, secondary ureteroscopy, or rarely, open/laparoscopic intervention.
7. Thermal Injury: Minimize laser use near urothelium, ensure adequate irrigation flow.

Postoperative Complications

Issues arising after fURS:

1. Douleur: Common, usually related to stent (flank pain, bladder spasms, dysuria) or passage of residual fragments. Managed with analgesics (NSAIDs, opioids), alpha-blockers (for stent discomfort), anticholinergics (for bladder spasms).
2. Hematuria: Expected, usually mild and self-limiting. Significant or prolonged hematuria requires evaluation (check stent position, rule out infection/clot obstruction).
3. Urinary Tract Infection (UTI)/Sepsis:
   • Incidence: UTI 1-5%, Sepsis < 1%.
   • Risk factors: Preoperative bacteriuria, prolonged procedure, high intrarenal pressure, residual fragments, stent placement.
   • Presentation: Fever, chills, flank pain, dysuria, altered mental status.
   • Management: Prompt recognition, blood/urine cultures, broad-spectrum IV antibiotics, supportive care (fluids, pressors if needed), ensure adequate drainage (check stent/catheter, consider percutaneous nephrostomy if obstructed).
4. Ureteral Obstruction:
   • Causes: Edema, clot, large residual fragment (steinstrasse), stent migration/malposition.
   • Presentation: Flank pain, nausea/vomiting, fever, decreased urine output.
   • Management: Imaging (ultrasound, CT), stent repositioning/exchange, possible percutaneous nephrostomy if severe obstruction.
5. Ureteral Stricture:
   • Incidence: 1-4%.
   • Risk factors: Ureteral trauma, prolonged UAS use, oversized UAS, thermal injury, previous ureteral surgery.
   • Presentation: Often delayed (weeks to months), with flank pain, recurrent UTIs, hydronephrosis.
   • Management: Endoscopic management (dilation, incision), stenting, or reconstruction for severe cases.
6. Stent-Related Complications:
   • Discomfort/pain: Alpha-blockers, anticholinergics, analgesics.
   • Migration: Repositioning or exchange.
   • Encrustation: Early removal (within 4-6 weeks typically), dissolution therapy for severe cases.
   • Forgotten stent: Complex management based on degree of encrustation, may require combined approaches (URS, PCNL, ESWL).

Stratégies de prévention

Minimizing complications:

1. Preoperative Optimization:
   • Sterile urine (treat UTI before elective procedures).
   • Appropriate antibiotic prophylaxis.
   • Consider pre-stenting for difficult anatomy.
   • Optimize medical comorbidities.
2. Technical Considerations:
   • Gentle wire/scope/sheath manipulation.
   • Appropriate UAS sizing (smallest effective size).
   • Maintain low intrarenal pressure (gravity irrigation, adequate outflow).
   • Systematic collecting system inspection.
   • Meticulous laser technique.
   • Limit procedure duration (consider staged approach for large stone burden).
3. Equipment Selection:
   • Appropriate scope size for anatomy.
   • Optimal laser settings for stone composition.
   • Suitable basket size and design.
   • Backup equipment availability.
4. Postoperative Care:
   • Appropriate stent duration.
   • Adequate hydration.
   • Pain management.
   • Patient education regarding expected symptoms vs. warning signs.
   • Clear follow-up plan.

Considérations particulières

Complex Renal Anatomy

Navigating challenging scenarios:

1. Lower Pole Stones:
   • Challenges: Acute infundibulopelvic angle, long infundibulum, narrow infundibulum.
   • Techniques: Maximal scope deflection, use of smaller laser fibers (200 µm), specialized baskets, repositioning stones to more accessible locations, consideration of alternative approaches (PCNL, SWL) for unfavorable anatomy.
2. Horseshoe Kidney:
   • Challenges: Abnormal calyceal orientation, high insertion of ureter.
   • Techniques: Careful study of preoperative imaging, flexible scope advantages, potential need for alternative access.
3. Calyceal Diverticula:
   • Challenges: Narrow/stenotic infundibulum, difficult identification of diverticular neck.
   • Techniques: Retrograde pyelogram for localization, guidewire placement if possible, consideration of combined approaches (retrograde + antegrade) for complex cases.
4. Transplant Kidneys:
   • Challenges: Anterior ureteral orifice, altered anatomy, immunosuppression concerns.
   • Techniques: Modified positioning, specialized cystoscopes, heightened infection prevention.

Pediatric Considerations

Adapting techniques for children:

1. Equipment Selection:
   • Smaller scopes (pediatric-specific or standard small-caliber scopes).
   • Smaller UAS (often 9.5/11.5 Fr) or sheathless technique.
   • Smaller laser fibers (200 µm).
2. Modifications techniques:
   • Gentler manipulation due to delicate tissues.
   • Lower irrigation pressures.
   • Shorter procedure duration.
   • Consideration of passive dilation with pre-stenting.
3. Outcomes: Generally comparable to adults with appropriate technique and equipment.

Grossesse

Managing stones in pregnant patients:

1. Indications: Limited to cases with refractory pain, obstruction, or infection not manageable with conservative measures.
2. Timing: Preferably second trimester if intervention necessary.
3. Radiation Considerations: Minimize or eliminate fluoroscopy, use ultrasound guidance when possible.
4. Technical Adaptations:
   • Modified positioning to avoid vena cava compression.
   • Shorter procedure duration.
   • Preference for temporary stenting over definitive stone treatment when possible.
   • Consideration of local or regional anesthesia.

Patients anticoagulés

Safe management strategies:

1. Risk Assessment: Balance bleeding risk vs. thrombotic risk.
2. Management Options:
   • Discontinuation when safe (in consultation with prescribing physician).
   • Bridging therapy for high-risk patients.
   • Proceeding with anticoagulation for low-risk procedures or high-risk patients.
3. Technical Considerations:
   • Gentler manipulation.
   • Lower irrigation pressures.
   • Dusting preferred over basketing.
   • Heightened vigilance for bleeding.
   • Liberal stent placement.

Outcomes and Quality Metrics

Stone-Free Rates

Defining success:

1. Definition Variability: No universal definition; commonly defined as fragments < 2-4 mm or absence of visible fragments on imaging.
2. Modalités d'imagerie: CT (most accurate), ultrasound, KUB (least sensitive).
3. Reported Outcomes:
   • Overall: 65-95% depending on definition, stone characteristics, and technique.
   • Stone size impact: < 1 cm: 80-90%; 1-2 cm: 70-80%; > 2 cm: 50-70%.
   • Location impact: Lower pole: 60-80%; non-lower pole: 80-90%.
4. Factors Affecting Stone-Free Rates:
   • Stone characteristics (size, location, composition, number).
   • Anatomical factors (infundibulopelvic angle, calyceal anatomy).
   • Technical factors (equipment, surgeon experience, technique).
   • Definition and imaging modality used.

Complication Rates

Benchmarking safety:

1. Overall Complication Rate: 5-10% (majority Clavien-Dindo grade I-II).
2. Specific Complications:
   • UTI: 1-5%.
   • Sepsis: < 1%.
   • Ureteral perforation: 1-2%.
   • Significant bleeding: < 1%.
   • Ureteral stricture: 1-4%.
3. Facteurs de risque de complications:
   • Prolonged procedure time.
   • Large stone burden.
   • Anatomical abnormalities.
   • Previous surgery.
   • Surgeon experience.
   • Equipment limitations.

Patient-Reported Outcomes

Beyond stone clearance:

1. Pain Scores: During recovery and related to stent discomfort.
2. Quality of Life Measures: Impact of procedure and stent on daily activities.
3. Return to Work/Activities: Typically 3-7 days.
4. Satisfaction des patients: Generally high, though stent discomfort is a common complaint.
5. Validated Instruments: Ureteral Stent Symptom Questionnaire (USSQ), Wisconsin Stone Quality of Life Questionnaire (WISQOL).

Cost-Effectiveness

Economic considerations:

1. Direct Costs:
   • Equipment (scope acquisition, maintenance, disposables).
   • Operating room time.
   • Hospital stay.
   • Readmissions/complications.
2. Indirect Costs:
   • Lost productivity.
   • Caregiver burden.
   • Transportation/follow-up visits.
3. Comparative Analysis:
   • fURS vs. SWL: fURS typically higher initial cost but potentially more cost-effective for certain stones due to higher stone-free rates.
   • fURS vs. PCNL: fURS typically lower cost for appropriate stone burdens.
   • Single-use vs. reusable scopes: Highly variable based on institutional factors.
4. Value-Based Considerations: Increasing emphasis on quality metrics and patient-reported outcomes in reimbursement models.

Orientations futures

Innovations technologiques

Emerging developments:

1. Scope Advancements:
   • Improved digital imaging (4K, 3D).
   • Enhanced deflection capabilities.
   • Larger working channels with maintained small outer diameter.
   • Novel materials for improved durability.
   • Disposable-reusable hybrid models.
2. Laser Technology:
   • Thulium fiber laser optimization.
   • Pulse modulation advancements.
   • Automated settings based on stone composition.
   • Real-time stone composition analysis.
3. Robotics and Automation:
   • Robotic scope manipulation.
   • Automated laser targeting.
   • Haptic feedback systems.
4. Imaging Enhancements:
   • Augmented reality integration.
   • Artificial intelligence for stone detection and composition analysis.
   • Improved fluoroscopy alternatives.
5. Accessory Innovations:
   • Novel basket designs.
   • Improved UAS with pressure monitoring.
   • Specialized tools for complex anatomy.

Training and Simulation

Developing expertise:

1. Virtual Reality Simulators: High-fidelity training platforms with haptic feedback and performance metrics.
2. 3D-Printed Models: Patient-specific anatomical models for pre-procedure planning and training.
3. Competency-Based Training: Structured curriculum with defined milestones and assessment tools.
4. Telementoring: Remote guidance for complex cases or training purposes.

Priorités de recherche

Areas for future investigation:

1. Standardized Reporting:
   • Uniform definitions of stone-free status.
   • Consistent complication classification.
   • Standardized outcome measures.
2. Efficacité comparative:
   • fURS vs. other modalities for specific stone scenarios.
   • Single-use vs. reusable scope outcomes.
   • Dusting vs. basketing techniques.
3. Optimisation de la sélection des patients:
   • Predictive models for treatment success.
   • Personalized approach based on stone and patient characteristics.
4. Complication Reduction:
   • Pressure monitoring and management.
   • Infection prevention strategies.
   • Ureteral injury prevention.

Avis de non-responsabilité médicale

This article is intended for educational and informational purposes only and does not constitute medical advice. The information provided about flexible ureteroscopy for renal calculi is based on current medical literature and clinical practice as of 2025 but may not reflect all individual variations in treatment responses or the full spectrum of clinical scenarios. Management decisions should always be made in consultation with qualified healthcare providers who can assess individual patient circumstances, risk factors, and specific needs.

The mention of specific products, technologies, or manufacturers does not constitute endorsement. Treatment protocols may vary between institutions and should follow local guidelines and standards of care. Readers are advised to consult with appropriate healthcare professionals regarding specific medical conditions and treatments. The authors, publishers, and Invamed disclaim any liability for any adverse effects resulting directly or indirectly from the information contained in this article.

Conclusion

Flexible ureteroscopy has revolutionized the management of renal calculi, offering a minimally invasive approach with excellent outcomes for appropriately selected patients. The evolution of flexible ureteroscopes, from fiberoptic to digital and now single-use platforms, has been accompanied by significant advancements in ancillary technologies such as laser lithotripsy systems, access sheaths, and stone retrieval devices. These technological innovations, combined with refined surgical techniques, have expanded the indications for fURS while improving safety and efficacy.

The success of flexible ureteroscopy depends on meticulous attention to detail throughout the patient care continuum. Preoperative preparation, including thorough patient evaluation, appropriate selection, and optimization, lays the foundation for successful outcomes. Intraoperative technique optimization, from access strategies to lithotripsy approaches, directly impacts stone clearance rates and complication profiles. Postoperative management, including stent care and follow-up protocols, ensures optimal recovery and long-term results.

Despite its many advantages, fURS is not without challenges and complications. Understanding the spectrum of potential adverse events, from minor issues like stent discomfort to serious complications such as sepsis or ureteral injury, is essential for prevention, early recognition, and effective management. A systematic approach to complication prevention, incorporating evidence-based practices and technological solutions, should be integrated into every aspect of the fURS procedure.

Special considerations arise in complex scenarios such as challenging renal anatomy, pediatric patients, pregnancy, and anticoagulation. These situations require thoughtful modifications to standard techniques and equipment, highlighting the importance of a personalized approach to each patient and clinical scenario.

As we look to the future, continued technological innovation promises to further enhance the capabilities and outcomes of flexible ureteroscopy. Advancements in scope design, imaging systems, laser technology, and accessory tools will likely expand the role of fURS in stone management. Simultaneously, improvements in training methodologies, including simulation and virtual reality, will help develop the next generation of skilled endourologists.

In conclusion, flexible ureteroscopy represents a cornerstone in the contemporary management of renal calculi. By understanding its capabilities, limitations, technical nuances, and potential complications, urologists can optimize outcomes while minimizing morbidity for patients with kidney stones. As technology and techniques continue to evolve, the role of fURS will likely expand, further cementing its position as an essential tool in the urologist’s armamentarium.

Références

1. Ghani KR, Andonian S, Bultitude M, et al. (2024). “Flexible Ureteroscopy and Laser Lithotripsy: The New Gold Standard for Renal Stones < 2 cm.” European Urology, 85(2), 178-186.

2. Traxer O, Keller EX, De Coninck V, Lechevallier E. (2023). “Flexible ureteroscopes: tips and tricks.” Nature Reviews Urology, 20(4), 217-230.

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