77. Percutaneous Nephrolithotomy (PCNL) Introduction | 经皮肾镜取石术（PCNL）介绍

What Is Percutaneous Nephrolithotomy (PCNL)?

Percutaneous nephrolithotomy (PCNL) is a minimally invasive surgical procedure used to remove large, complex, or otherwise difficult-to-treat kidney stones. Unlike ESWL or ureteroscopy, which work through natural body openings, PCNL creates a small tunnel directly into the kidney through the skin of the back. This direct access allows the urologist to break up and remove even very large stones in a single procedure, achieving the highest stone-free rates of any treatment modality.

Why PCNL Is Considered the Gold Standard:

"For stones larger than 20mm, staghorn calculi, or stones resistant to other treatments, PCNL offers stone-free rates of 85-95% after a single procedure. No other treatment approach can match this level of effectiveness for large stone burdens."

Core Principle of PCNL:

Direct Kidney Access: A tract is created through the back directly into the kidney collecting system
Visual Stone Treatment: A rigid nephroscope provides direct visualization of stones
Mechanical Fragmentation: Ultrasound, pneumatic, or laser lithotripsy breaks stones
Immediate Removal: Stone fragments are suctioned or grasped and removed through the tract
High Efficiency: Large stone volumes can be cleared in a single session

Figure 1:the surgeon passes a telescope through the skin into the kidney and the stones are broken down or extracted .

Indications: When PCNL Is the Best Choice

According to AUA and EAU guidelines, PCNL is the preferred treatment for specific stone presentations where other modalities have limited effectiveness. Understanding these indications helps ensure patients receive the most appropriate treatment for their specific stone burden.

Primary Indications for PCNL

Stones Best Treated by PCNL:

Large Renal Stones (>20mm): ESWL has poor success rates for stones over 2cm
Staghorn Calculi: Branched stones filling the renal collecting system
Lower Pole Stones >15mm: ESWL and URS have limited success in this location
Hard Stone Compositions: Cystine, calcium oxalate monohydrate resistant to ESWL
Obesity: Skin-to-stone distance too great for effective ESWL
Failed Prior Treatment: Stones remaining after ESWL or URS attempts
Anatomical Abnormalities: Horseshoe kidney, malrotated kidney with stones
Symptomatic Calyceal Diverticulum Stones: Stones in outpouchings of the collecting system

Stone Size and Treatment Selection

Stone Size	Location	Recommended Treatment	PCNL Stone-Free Rate
> 20mm (2cm)	Kidney	PCNL first-line	85-95%
> 30mm (3cm)	Kidney	PCNL	80-90%
Staghorn calculus	Any kidney location	PCNL	75-85%
15-20mm	Lower pole	PCNL or URS	80-90%
> 15mm	Upper/mid pole	PCNL or URS	85-95%
Cystine stone	Any	PCNL or URS	75-90%

Comparison with Alternative Treatments

Stone Scenario	ESWL Success	URS Success	PCNL Success
25mm renal stone	30-50%	60-75%	85-95%
Staghorn calculus	< 20%	50-70%	75-85%
Cystine stone 20mm	< 30%	70-80%	80-90%
Lower pole 18mm	40-55%	60-75%	80-90%

The PCNL Procedure: Step-by-Step

PCNL is a complex procedure requiring specialized training and equipment. Understanding the surgical steps helps patients appreciate the technical expertise involved and what to expect during their hospital stay. The procedure typically takes 1.5 to 3 hours and requires general anesthesia.

Pre-Operative Preparation

Imaging Review: CT scan analyzed to plan optimal percutaneous access tract - usually through the calyx providing the shortest and safest route to the stone
Antibiotic Prophylaxis: Broad-spectrum IV antibiotics administered pre-operatively
Patient Positioning: Prone position (lying face down) with appropriate padding to prevent pressure injuries
Anesthesia: General endotracheal anesthesia with muscle relaxation
Retrograde Catheter: Ureteral catheter placed cystoscopically to inject contrast and inflate the collecting system

Phase 1: Percutaneous Access and Tract Creation

Calyx Puncture: Under fluoroscopic or ultrasound guidance, a needle is advanced through the skin and into a target calyx
Guidewire Placement: A guidewire is threaded through the needle into the collecting system
Tract Dilation: The tract is dilated using sequential dilators or a balloon dilator to create a working channel (typically 24-30 French)
Amplatz Sheath Placement: A plastic access sheath is advanced over the dilator to maintain the tract
Nephroscope Insertion: The rigid nephroscope is passed through the sheath into the kidney

Phase 2: Stone Fragmentation and Removal

Stone Visualization: Direct inspection of the stone through the nephroscope
Lithotripsy: Stone fragmented using ultrasound lithotripter, pneumatic lithotripter, or holmium laser
Suction Evacuation: Ultrasound lithotripter fragments simultaneously suctioned away
Fragment Extraction: Larger pieces grasped with forceps or baskets and removed through the sheath
Calyceal Inspection: All calyces inspected for residual fragments using flexible nephroscope if needed
Fluoroscopic Verification: X-ray confirms stone clearance before tract closure

Phase 3: Tract Closure and Drainage

Nephrostomy Tube: A drainage tube placed through the tract into the kidney (optional in uncomplicated cases)
Ureteral Stent: Double-J stent placed from kidney to bladder to ensure drainage
Tract Sealing: Some surgeons use hemostatic agents to reduce bleeding
Dressing: Sterile dressing applied to the back incision site
Recovery: Patient transferred to recovery room for monitoring

Modern Variations of PCNL:

Tubeless PCNL: No nephrostomy tube placed - reduces pain and recovery time
Totally Tubeless PCNL: No nephrostomy tube or ureteral stent placed
Supine PCNL: Patient positioned on back instead of stomach
ECIRS (Endoscopic Combined Intrarenal Surgery): Combined antegrade and retrograde approach
Ultrasound-Guided Access: Reduces radiation exposure for patient and staff

Figure 2:Steps in PCNL surgery

Figure 3:Stone being broken during PCNL

Miniaturized PCNL Techniques

Recent advances in PCNL have led to the development of miniaturized techniques that reduce tract size and associated complications while maintaining high stone-free rates. These approaches represent the evolution of percutaneous stone surgery toward less invasive methods.

Types of Miniaturized PCNL

Technique	Tract Size	Indications	Advantages
Mini-PCNL (miniperc)	12-20 Fr	Stones 15-25mm	Less bleeding, less pain than standard PCNL
Ultra-mini PCNL	11-13 Fr	Stones 10-20mm	Can be tubeless, faster recovery
Micro-PCNL	4.8 Fr	Small stones 10-15mm	All-seeing needle, minimal trauma
Standard PCNL	24-30 Fr	Large stones >20mm	Maximum stone clearance efficiency

Benefits of Miniaturized PCNL:

Reduced Bleeding: Smaller tracts damage fewer blood vessels
Less Postoperative Pain: Smaller incision and tract cause less tissue trauma
Tubenless Options: Many mini-PCNL cases need no nephrostomy tube
Shorter Hospital Stay: Often discharged within 24 hours
Faster Return to Work: Recovery time significantly reduced
Comparable Stone-Free Rates: For appropriately selected stones

Post-Operative Care and Recovery

PCNL recovery involves a brief hospital stay and several weeks of gradual return to normal activities. Understanding the expected recovery course helps patients plan appropriately and recognize when medical attention is needed.

Hospital Stay (Typically 1-3 Days)

Inpatient Monitoring:

Vital Signs: Blood pressure, heart rate, temperature monitored regularly
Urine Output: Nephrostomy tube output measured and monitored for color
Pain Control: IV pain medications transitioning to oral analgesics
Nephrostomy Tube Care: Tube secured, drainage bag emptied regularly
Antibiotics: Continued if indicated by intraoperative urine culture
Blood Tests: Hemoglobin checked to monitor for significant bleeding

Nephrostomy Tube Management

Tube Care Instructions:

Positioning: Keep drainage bag below kidney level at all times
Securement: Tube taped to skin to prevent accidental dislodgement
Site Care: Keep insertion site clean and dry; watch for signs of infection
Drainage Monitoring: Note urine color - may be pink initially, should clear
Clamp Trial: Before removal, tube may be clamped to test urine drainage through normal route
Removal Timing: Usually 1-3 days post-op; sometimes removed before discharge

Recovery Timeline

Time Period	Expected Recovery	Activity Level	Follow-Up
Days 1-3	Hospital stay, nephrostomy tube	Bed rest, short walks	Daily inpatient assessment
Days 4-7	Discharged home, mild discomfort	Light home activities	Nephrostomy removal if still in
Week 2	Improving energy, decreasing pain	Walking, light tasks	Office visit, imaging
Weeks 3-4	Near-normal activity level	Return to desk work	Stent removal if placed
Weeks 4-6	Full recovery	Resume all normal activities	Stone analysis, prevention plan

When to Seek Medical Attention

Post-PCNL Warning Signs:

Fever over 101F (38.3C): May indicate infection
Heavy Bleeding: Large blood clots or bright red urine persisting beyond 48 hours
Severe Pain: Not controlled by prescribed pain medications
Nephrostomy Tube Issues: Tube dislodgement, no drainage, or leakage around tube
Signs of Infection: Increasing redness, warmth, or drainage at incision site
Difficulty Breathing: Could indicate rare fluid absorption complication

Figure 4:Scar post-PCNL

Complications and Risk Management

PCNL, while highly effective, carries a higher complication profile than ESWL or URS due to its invasive nature. Understanding these risks and how they are managed helps patients make informed decisions and participate in their post-operative care.

Intraoperative Complications

Complication	Frequency	Risk Factors	Management
Bleeding requiring transfusion	2-7%	Large tract, multiple punctures, diabetes	Transfusion, selective embolization if severe
Colonic injury	0.2-0.5%	Posterior calyx access, thin patients	Conservative or surgical repair
Pleural injury	0.4-1%	Upper pole access, supracostal puncture	Chest tube if pneumothorax/hemothorax
Sepsis	0.5-2%	Infected stones, positive urine culture	IV antibiotics, ICU if severe
Fluid absorption	1-3%	High irrigation pressure, long procedure	Diuretics, electrolyte monitoring

Postoperative Complications

Complication	Frequency	Prevention	Management
Fever	15-30%	Pre-op antibiotics, sterile technique	Culture-directed antibiotics
Residual stone fragments	10-25%	Thorough calyceal inspection	Observation, second look, or ESWL
Urinary leak	1-3%	Proper nephrostomy placement	Continued drainage, stent placement
Arteriovenous fistula	0.5-1%	Careful tract placement	Selective angioembolization

Risk Reduction Strategies:

Pre-operative Planning: CT-based access planning to avoid surrounding organs
Experienced Surgeon: Higher volume centers have lower complication rates
Antibiotic Prophylaxis: Reduces infection-related complications
Careful Tract Selection: Avoiding upper pole when possible reduces pleural injury
Controlled Irrigation: Low-pressure irrigation minimizes fluid absorption