76. Ureteroscopy (URS) with Laser Lithotripsy Procedure | 输尿管镜碎石术（URS）操作过程

Understanding Ureteroscopy: The Minimally Invasive Approach

Ureteroscopy with laser lithotripsy has become one of the most commonly performed procedures for kidney and ureteral stones. Unlike ESWL, which breaks stones from outside the body, ureteroscopy involves passing a thin telescope through the natural urinary tract to directly visualize and treat stones. This endoscopic approach offers several advantages, including the ability to treat stones regardless of composition, precise stone targeting, and immediate stone removal in many cases.

Key Advantages of URS:

"Ureteroscopy is the most versatile kidney stone treatment. It works on stones of any composition, including hard cystine and calcium oxalate monohydrate stones that resist ESWL. Modern flexible ureteroscopes can access nearly every part of the urinary tract, and the holmium laser fragments stones efficiently with minimal surrounding tissue damage."

Figure 1: URS is minimally invasive, offering rapid symptom relief with short recovery time.

Types of Ureteroscopes: Rigid vs. Flexible

Modern ureteroscopy utilizes two main types of instruments: rigid ureteroscopes for lower ureteral stones and flexible ureteroscopes for upper tract and kidney stones. Understanding the differences between these instruments helps explain why specific scopes are chosen for different clinical situations.

Rigid Ureteroscopes

Characteristics of Rigid URS:

Design: Straight, non-bending metal instrument
Application: Primarily for distal and mid-ureteral stones
Advantages: Larger working channel, better irrigation, easier stone fragmentation
Diameter: Typically 6.5-9.5 French
Limitations: Cannot navigate into kidney calyces or around anatomical curves
Optics: Rod-lens system provides excellent image quality

Flexible Ureteroscopes

Characteristics of Flexible URS:

Design: Steerable tip with active deflection (up to 270 degrees)
Application: Kidney stones, upper ureteral stones, lower pole calyces
Advantages: Access to entire collecting system, retrograde renal access
Diameter: Typically 7.5-9.5 French
Deflection: Primary and secondary active deflection for complex anatomy
Technology: Digital chip technology provides superior image quality

Feature	Rigid Ureteroscope	Flexible Ureteroscope
Stone Location	Distal/Mid Ureter	Any location including kidney
Deflection Ability	None	Up to 270 degrees
Working Channel Size	Larger (3.4-5.5 Fr)	Smaller (3.6 Fr)
Irrigation Flow	Better	Moderate
Durability	Very durable	More fragile, higher repair rate
Cost	Lower	Higher

Figure 2: URS is minimally invasive, offering rapid symptom relief with short recovery time.

Figure 3: Rigid vs flexible ureteroscope

Pre-Procedure Preparation and Patient Evaluation

Thorough pre-operative assessment is essential for safe and successful ureteroscopy. Patient evaluation includes medical history review, imaging studies, laboratory tests, and appropriate medication management to minimize perioperative risks.

Required Pre-Operative Evaluation

Pre-Procedure Checklist:

CT Imaging: Non-contrast CT to confirm stone size, location, density, and anatomy
Urine Culture: Rule out active urinary tract infection (must be sterile)
Blood Tests: Complete blood count, coagulation profile, serum creatinine
ECG: For patients with cardiac history or over age 50
Medication Review: Management of anticoagulants, antiplatelet agents
Allergy Assessment: Contrast and latex allergies if applicable

Medication Management

Medication Class	Pre-Procedure Action	Post-Procedure Resumption
Warfarin	Stop 5 days before, bridge with heparin if needed	24-48 hours after if no bleeding
Aspirin	Stop 7 days before (if elective)	48-72 hours after
Clopidogrel	Stop 5-7 days before (consult cardiology)	Per cardiology guidance
DOACs (apixaban, rivaroxaban)	Stop 48 hours before (72h if CrCl <30)	24-48 hours after
Metformin	Hold day of procedure if contrast used	48 hours after if normal renal function

Anesthesia Planning

Anesthesia Options for URS:

General Anesthesia: Most common - ensures patient comfort and prevents movement during delicate work
Spinal Anesthesia: Alternative for select patients, avoids general anesthesia risks
Local with Sedation: Rarely used for diagnostic ureteroscopy only
Airway Management: Endotracheal intubation or laryngeal mask airway
Muscle Relaxation: Neuromuscular blockade prevents patient movement during laser firing

The URS Procedure: Step-by-Step Operative Technique

Understanding the technical steps of ureteroscopy helps patients appreciate the complexity and precision required for this procedure. Each phase requires specialized skills and equipment to ensure safe access, effective stone treatment, and minimal complications.

Phase 1: Patient Positioning and Preparation

Lithotomy Position: Patient placed in dorsal lithotomy position with legs in stirrups, allowing access to the urethra
Surgical Prep: Sterile preparation of perineum and external genitalia with antiseptic solution
Draping: Sterile drapes placed to create a clean operative field
Antibiotic Administration: Prophylactic IV antibiotics given within 60 minutes of incision
C-arm Setup: Fluoroscopy machine positioned for real-time imaging guidance

Phase 2: Cystoscopy and Ureteral Access

Cystoscopy: Rigid cystoscope inserted through urethra into bladder to inspect anatomy
Ureteral Orifice Identification: Both ureteral openings visualized and assessed
Guidewire Placement: Hydrophilic guidewire advanced into ureter under fluoroscopic guidance
Ureteral Dilation (if needed): Sequential dilators or balloon dilator passed if ureter is narrow
Access Sheath Placement: Ureteral access sheath advanced to facilitate scope re-entry and irrigation

Phase 3: Ureteroscope Advancement to Stone

Scope Insertion: Flexible ureteroscope passed through access sheath or directly over guidewire
Ureteral Inspection: Careful advancement while visualizing ureteral mucosa for abnormalities
Stone Localization: Scope advanced until stone is directly visualized
Assessment: Stone size, appearance, and surrounding anatomy evaluated
Irrigation Management: Continuous saline irrigation maintains clear visualization and low intrarenal pressure

Phase 4: Laser Lithotripsy

Holmium:YAG Laser Stone Fragmentation:

Laser Fiber Insertion: 200-365 micron laser fiber passed through working channel
Energy Settings: Typically 0.5-1.5 Joules at 5-15 Hz frequency
Fragmentation Technique: Stone broken into small fragments using "dusting" or "fragmentation" approach
Contact Method: Laser fiber placed in direct contact with stone surface
Cooling: Continuous irrigation prevents overheating of surrounding tissues
Fluoroscopic Monitoring: Periodic X-ray checks track stone fragmentation progress

Phase 5: Stone Extraction

Basket Retrieval: Nitinol stone basket passed through working channel to capture fragments
Fragment Removal: Fragments extracted through scope or alongside scope
Stone Analysis: Retrieved fragments sent for chemical composition analysis
Complete Inspection: Entire collecting system re-examined to ensure no residual fragments
Irrigation and Clearance: Thorough irrigation to flush small debris

Phase 6: Stent Placement and Completion

Stent Decision: Ureteral stent placed based on procedure complexity, edema, and surgeon preference
Stent Insertion: Double-J stent advanced over guidewire with fluoroscopic confirmation
Position Verification: Stent position confirmed with fluoroscopy - curls in kidney and bladder
Scope Withdrawal: Ureteroscope and access sheath carefully removed
Final Cystoscopy: Brief inspection to confirm no urethral or bladder injury
Catheter Placement: Foley catheter may be placed temporarily in complex cases

Figure 4: URS Procedure Steps Diagram

Holmium Laser Technology in Ureteroscopy

The holmium:YAG laser has revolutionized endoscopic stone treatment. This versatile tool not only fragments stones efficiently but also produces minimal collateral tissue damage, making it the gold standard for intracorporeal lithotripsy.

Laser Physics and Stone Interaction

How Holmium Laser Breaks Stones:

Wavelength: 2100 nanometers - absorbed by water and stone material
Pulse Duration: Short pulses (microseconds) create cavitation bubbles
Photothermal Effect: Stone material vaporized at fiber tip contact point
Photomechanical Effect: Shock waves from cavitation assist fragmentation
Penetration Depth: Only 0.4mm - minimal surrounding tissue damage
Tissue Safety: Ureteral mucosa tolerates brief laser exposure well

Laser Settings and Techniques

Technique	Energy (J)	Frequency (Hz)	Power (W)	Best For
Dusting	0.2-0.5	10-20	5-10	Soft stones, minimal retrieval
Fragmentation	0.8-1.5	6-10	10-15	Hard stones, basket extraction
Popcorn Effect	0.5-1.0	15-20	10-20	Small fragments in calyx
Low-Power Dusting	0.2-0.3	20-30	6-9	Fine powder, minimal retropulsion

Laser Fiber Types

Available Fiber Specifications:

200 micron: Thinnest, maximum irrigation, best deflection - ideal for flexible URS
272 micron: Balance of durability and irrigation
365 micron: Most durable, higher energy delivery, less irrigation - for rigid URS
550 micron: Maximum power, used in percutaneous procedures

Figure 5: Holmium laser to break the stone

Figure 6: Dormia basket to trap / extract the stone

Post-Procedure Care and Recovery

Recovery after ureteroscopy is generally rapid, with most patients discharged home the same day. Understanding the expected post-operative course helps patients distinguish normal recovery symptoms from potential complications.

Immediate Post-Operative Period (Day 0-1)

Recovery Room Care:

Monitoring: Vital signs, urine output, pain assessment
Oral Intake: Resume drinking and eating once fully awake
Pain Control: Oral NSAIDs or acetaminophen typically sufficient
Stent Symptoms: Patient educated about expected stent-related discomfort
Discharge Criteria: Able to void, pain controlled, tolerating oral intake

Expected Post-Operative Symptoms

Symptom	Frequency	Duration	Management
Dysuria (burning with urination)	Very common (80-90%)	2-5 days	Hydration, phenazopyridine if needed
Hematuria (blood in urine)	Very common (90%+)	1-3 days	Increased fluid intake
Frequency/Urgency	Common (70-80%)	Until stent removed	Anticholinergics if severe
Flank discomfort	Common (60-70%)	3-7 days	NSAIDs, activity modification
Stent irritation	Variable (30-60%)	While stent in place	Alpha-blockers, pain medication

Activity and Recovery Timeline

Return to Activities:

Day 1-2: Rest at home, light walking encouraged
Day 3-5: Return to desk work and light daily activities
Week 1-2: Avoid heavy lifting over 10 pounds
Week 2: Most patients resume normal exercise routine
Stent Removal: Typically 3-14 days post-procedure (office procedure)
Full Recovery: 1-2 weeks for most patients

Follow-Up Care

Post-Procedure Follow-Up Plan:

Stent Removal: Scheduled office visit for cystoscopic stent removal
Imaging: KUB X-ray or ultrasound 2-4 weeks post-procedure to assess stone-free status
Stone Analysis: Results discussed and prevention plan initiated
Metabolic Evaluation: Considered for recurrent stone formers
Prevention Counseling: Dietary and lifestyle recommendations

Complications and Safety Considerations

While ureteroscopy is generally safe, complications can occur. Understanding these potential adverse events helps patients recognize warning signs and seek appropriate medical attention when needed.

Intraoperative Complications

Complication	Frequency	Prevention	Management
Ureteral perforation	1-3%	Gentle technique, avoid over-distension	Stent placement, drain if needed
Ureteral avulsion	< 1%	Never force instrument advancement	Surgical repair, possible reimplantation
Stone migration (retropulsion)	5-10%	Low irrigation pressure, laser settings	May require second procedure
Submucosal stone	1-2%	Avoid pushing stone into wall	Stent and delayed second look
Bleeding	2-5%	Avoid aggressive manipulation	Irrigation, observation, rarely transfusion

Postoperative Complications

Complication	Frequency	Warning Signs	Treatment
Fever/UTI	5-15%	Temperature >38.5C, chills	Antibiotics, urine culture
Sepsis	0.5-2%	High fever, confusion, low BP	Hospital admission, IV antibiotics
Steinstrasse	2-5%	Colicky pain, obstruction	Stent placement or repeat URS
Ureteral stricture	1-2%	Gradual onset flank pain	Dilation, incision, or reconstruction
Persistent pain	5-10%	Pain beyond expected recovery	Imaging, assess for residual stones

When to Seek Emergency Care:

Fever over 101F (38.3C) with chills
Inability to urinate with severe bladder pain
Uncontrolled pain despite medication
Large blood clots in urine
Signs of confusion or severe weakness
Stent displacement (string no longer visible)