What is the standard protocol for percutaneous nephrolithotomy (PCNL) procedure?

Standard Protocol for Percutaneous Nephrolithotomy (PCNL)

PCNL remains the standard treatment for large renal stones, with specific protocols for positioning, access, dilation, stone removal, and post-operative care that optimize outcomes while minimizing complications. 1

Indications and Patient Selection

• PCNL is the first-line treatment for renal stones >20 mm due to significantly higher stone-free rates compared to other treatment modalities 1, 2
• For lower pole stones 10-20 mm, PCNL offers superior success rates (87%) compared to ureteroscopy (81%) and shock wave lithotripsy (58%) 1
• Contraindications include untreated UTI, tumor in the access tract, suspected malignant kidney tumors, and pregnancy 1
• Patients on anticoagulants require careful monitoring and potential medication adjustment before proceeding with PCNL 1

Pre-Procedure Protocol

• Preoperative imaging with ultrasound or CT is essential to identify interposed organs (liver, spleen, bowel) and plan the access route 1
• Antibiotic prophylaxis is mandatory to prevent infectious complications 1
• Anesthesia options include general anesthesia (most common) or spinal/epidural anesthesia in select high-risk patients 3, 4

Procedural Technique

Positioning

• Both prone and supine positions are equally safe for PCNL 1
• Supine position offers the advantage of simultaneous retrograde access if needed 1

Access and Puncture

• Fluoroscopy is the standard guidance method for renal puncture 1
• Ultrasound guidance is an alternative that reduces radiation exposure and has lower complication rates 1
• Flexible ureteroscopy can enhance puncture accuracy when needed 1

Tract Dilation

• Options include metallic telescopic, single-step, and balloon dilators 1
• Single-step dilation may shorten operative time and reduce complications 1
• Standard access tracts are 24-30 F, though smaller sheaths (<18 F) are increasingly used 1

Stone Fragmentation and Removal

• Lithotripsy methods include ultrasonic, pneumatic, and combined systems for rigid nephroscopy 1
• Normal saline must be used for irrigation to prevent electrolyte abnormalities 1, 2
• Flexible nephroscopy should be routinely performed to access stone fragments that migrate to areas inaccessible by rigid nephroscope 1, 2
• Mini-PCNL (12-22 F) and standard PCNL (>22 F) provide similar stone-free rates, but mini-PCNL reduces blood loss, transfusion rates, and hospital stay 1
• Suction during PCNL can reduce intrarenal pressure and improve outcomes 1

Post-Procedure Management

Drainage Options

• Placement of a nephrostomy tube or double-J stent depends on factors including residual stones, bleeding, urine leakage, or risk of infection 1
• Small-bore nephrostomy tubes reduce post-operative pain 1
• Tubeless PCNL (no nephrostomy tube) reduces pain and length of hospital stay 1
• Totally tubeless PCNL (no nephrostomy or stent) is effective in uncomplicated cases 1
• Double-J stents allow shorter hospital stays but may slightly impact quality of life 1

Complications and Their Management

• Common complications include fever (10.8%), transfusion requirement (7%), thoracic complications (1.5%), sepsis (0.5%), organ injury (0.4%), embolization (0.4%), urinoma (0.2%), and mortality (0.05%) 1
• Risk factors for complications include stone burden, operative time, and comorbidities 1
• Blood transfusion rates range from 6.2% to 7% according to large studies 1, 4

Special Considerations

• For patients with obstructing stones and suspected infection, urgent drainage of the collecting system with a stent or nephrostomy tube is mandatory before definitive stone treatment 2
• In patients with negligible kidney function, nephrectomy may be considered instead of PCNL 1, 2
• Spinal or epidural anesthesia can be considered in patients with high anesthetic risk who are unfit for general anesthesia 3, 5

Pitfalls and Caveats

• Failure to perform flexible nephroscopy may result in residual stone fragments and future stone events 1
• Using non-isotonic irrigation solutions increases the risk of hemolysis, hyponatremia, and heart failure 1
• Routine post-procedure imaging is essential to confirm stone-free status 1
• Staged procedures may be necessary for complex or large stone burdens 1