What is Percutaneous Nephrolithotomy (PCNL)?

Percutaneous Nephrolithotomy (PCNL)

Percutaneous Nephrolithotomy (PCNL) is a minimally invasive surgical procedure that creates direct access to the kidney through a small incision in the back to remove large kidney stones that cannot be effectively treated with other methods. It is the gold standard treatment for large renal stones (>10mm) with superior stone-free rates compared to other treatment modalities 1.

Indications for PCNL

• Large stones >10mm in the kidney, especially lower pole stones
• Complex or branched (staghorn) renal stones
• Stones resistant to other treatment methods
• High stone burden requiring efficient removal

For lower pole stones 10-20mm in size, PCNL achieves a median success rate of 87% compared to 81% for ureteroscopy (URS) and only 58% for shock wave lithotripsy (SWL). When stone burden exceeds 20mm, PCNL becomes even more advantageous as SWL success rates drop to just 10% 1.

Procedure Overview

The PCNL procedure involves several key steps:

1. Patient positioning - typically prone position, though supine approaches are increasingly used
2. Percutaneous access - creating a tract from the skin to the kidney collecting system
3. Tract dilation - expanding the access tract to allow instrument passage
4. Stone fragmentation - breaking up stones using various energy sources
5. Stone removal - extracting stone fragments
6. Drainage - placing tubes for postoperative drainage when needed

Technical Considerations

Access and Equipment

• Imaging guidance is essential for safe access (fluoroscopy and/or ultrasound)
• Flexible nephroscopy should be routinely performed during PCNL to access all areas of the collecting system and remove stone fragments that may migrate to inaccessible areas (Strong Recommendation; Evidence Strength: Grade B) 1
• Normal saline irrigation must be used during PCNL to prevent electrolyte abnormalities, hemolysis, hyponatremia, and heart failure (Strong Recommendation; Evidence Strength: Grade B) 1

Drainage Options

• In uncomplicated PCNL cases where patients are presumed stone-free, placement of a nephrostomy tube is optional (Conditional Recommendation; Evidence Strength: Grade C) 1
• "Tubeless PCNL" (using only a ureteral stent for drainage without a nephrostomy tube) can be considered to reduce postoperative discomfort 1, 2
• The tubeless approach should be avoided if there is active hemorrhage or if another percutaneous procedure will likely be needed 1

Efficacy and Outcomes

• PCNL achieves stone-free rates of 84-87% for large renal stones 1, 2
• Modern ambulatory PCNL (aPCNL) in selected patients can be performed safely in outpatient settings with low complication rates (2.4% hospital transfer rate, 4.2% 30-day readmission rate) 2

Contraindications and Alternative Approaches

Contraindications to PCNL include:

• Uncorrectable coagulopathy or anticoagulation therapy that cannot be discontinued
• Anatomic abnormalities preventing proper patient positioning
• Active urinary tract infection
• Pregnancy

For patients with contraindications to PCNL, staged ureteroscopy (URS) may be offered as an alternative, though it may require multiple procedures and may not achieve complete stone clearance 1.

Complications and Management

Potential complications include:

• Bleeding (most common significant complication)
• Infection/sepsis
• Adjacent organ injury (colon, pleura, spleen)
• Fluid absorption leading to volume overload

Recent Advances

Recent innovations in PCNL include:

• Miniaturized equipment (mini-PCNL, micro-PCNL) to reduce morbidity
• Endoscopic-guided access techniques for more precise tract creation
• Combined antegrade and retrograde approaches
• Tubeless and totally tubeless techniques in selected cases 3

PCNL has evolved from a standardized procedure to one with multiple technical variations that can be tailored to the specific stone characteristics and patient factors 3.