Percutaneous nephrolithotomy is the standard of care for large and complex renal stones. A tract is dilated into the collecting system, and stones are fragmented and extracted under direct nephroscopic vision. It offers the highest single-procedure stone-free rates but carries the most morbidity of the stone interventions.
Indications and Contraindications
PCNL is the standard for stones >2 cm, staghorn calculi, and complex or lower-pole stones not suited to less invasive options.
- Absolute contraindication: untreated UTI.
- Relative: anticoagulation/antiplatelet therapy that cannot be stopped, and anatomic derangements (contractures, flexion deformities) that preclude positioning. Offer staged URS to non-candidates.
- Stop aspirin/antiplatelets ~7 days before; bridge high-thrombotic-risk patients with LMWH (stop 24 h before, resume 24 h after). Obesity does not increase overall morbidity but complicates prone-position ventilation.
Percutaneous Access
The preferred entry is posteriorly, along the calyceal axis, through the papilla (Brödel's relatively avascular line). A hydrophilic glide wire is the preferred initial wire. Over-advancement of the dilator/sheath is the most common serious access error, risking collecting-system trauma and haemorrhage.
| Access | Best for | Trade-offs |
|---|---|---|
| Upper pole | Staghorn (single tract), high stone volume, concomitant endopyelotomy; in line with the renal axis (minimal torque with rigid instruments) | Risk of pleural, liver, and splenic injury (often supracostal) |
| Lower pole | Lower-pole non-staghorn or partial-staghorn stones | Low pleural/visceral risk, but a longer tract, greater skin-to-stone distance, worse UPJ access, and slightly higher colonic-injury risk |
A supracostal puncture (for upper-calyceal/staghorn burden or endopyelotomy) is performed in full expiration, with a chest exam at the end. In horseshoe kidneys, enter through a posterior calyx (more medial than usual because of the altered renal axis).
Technique
- Antibiotic prophylaxis for all cases (≤24 h): a 1st/2nd-generation cephalosporin, or an aminoglycoside with clindamycin or metronidazole.
- Normal saline irrigation is mandatory (PCNL can absorb irrigant).
- Flexible nephroscopy should be used in every PCNL to survey the entire collecting system for residual fragments — it raised stone-free rates to 92.5% vs 70% (rigid alone) in an RCT.
Intracorporeal Lithotripters
| Device | Type | Notes |
|---|---|---|
| Holmium laser (Ho:YAG) | Flexible | Safest and most versatile; ~0.5–1 mm thermal zone; fragments any composition; minimal retropulsion |
| Electrohydraulic (EHL) | Flexible | Unfocused underwater spark; highest perforation risk — keep ≥2–5 mm from the wall |
| Ballistic (pneumatic) | Rigid | "Jackhammer" effect; lowest perforation risk but high stone retropulsion |
| Ultrasonic | Rigid | Fragments and simultaneously aspirates fragments (<2 mm); limited in the ureter (rigid probe). Combined ultrasonic/pneumatic units (e.g. LithoClast) pair fragmentation with evacuation |
Nephrostomy Tube vs Tubeless
A nephrostomy tube promotes haemostasis, allows re-entry for a second look, aids tract healing, and prevents urine extravasation, but increases postoperative pain, narcotic use, and hospital stay. "Tubeless" PCNL (a stent or nothing) gives similar stone-free and complication rates in uncomplicated, presumed-stone-free cases — but not with active haemorrhage or a planned second procedure.
Complications
- Haemorrhage — the most significant complication (transfusion <1–10%); risk rises with multiple/large tracts, non-balloon dilation, supracostal access, pelvic perforation, prolonged time, and large stone burden. Stepwise management: (1) place a nephrostomy tube (the source is usually venous), (2) clamp it to tamponade, (3) Kaye tamponade-balloon catheter, (4) angiography ± embolization, (5) partial nephrectomy as a last resort. Delayed bleeding is usually an AV fistula or pseudoaneurysm → selective arteriogram with transcatheter embolization.
- Sepsis — best predicted by stone or renal-pelvic urine culture (fragmentation releases endotoxin and viable bacteria even when bladder urine is sterile); ~⅓ of stented patients are colonised (Enterococcus, S. epidermidis most common).
- Renal-pelvis / ureteric perforation — minor perforations are tolerated with a low-pressure (Amplatz) sheath; a significant perforation requires termination and nephrostomy drainage. Intraperitoneal extravasation narrows the pulse pressure (rising diastolic) before ventilation difficulty or rising CVP.
- Venous gas embolism — rare but potentially fatal; a mill-wheel murmur, hypoxaemia, and hypotension → reposition head-down, right side up.
- Pleural injury (pneumothorax/hydrothorax) with supracostal puncture; colon injury (thin or elderly patients, anterior puncture, prior bowel bypass, horseshoe kidney) — extraperitoneal perforation is managed by withdrawing the nephrostomy to act as a colostomy tube, while intraperitoneal injury (peritoneal signs) needs exploration.
Salvage Options
Open, laparoscopic, or robotic stone surgery is reserved for failed PCNL/SWL/URS or an anatomic abnormality requiring simultaneous repair (UPJ obstruction, infundibular stenosis) — scarring from open surgery complicates any future stone procedure. Nephrectomy (or partial nephrectomy) is an option for a non-functioning kidney, or a localised area of irreversibly poor function, with a normal contralateral kidney.
Key Exam Points
- Standard for stones >2 cm and staghorn calculi; the only absolute contraindication is untreated UTI.
- Access through the posterior calyceal papilla along Brödel's line; over-advancing the sheath is the commonest serious access error.
- Upper-pole access suits staghorns (single tract) but risks pleural/visceral injury; lower-pole access is safer but gives worse UPJ access.
- Flexible nephroscopy in every case; normal saline irrigation is mandatory.
- Intracorporeal lithotripters: Ho:YAG (versatile), EHL (highest perforation risk), ballistic (high retropulsion), ultrasonic (simultaneous aspiration).
- Haemorrhage ladder: nephrostomy → clamp → Kaye balloon → angioembolization → partial nephrectomy; delayed bleeding = AV fistula/pseudoaneurysm → embolization.
- Post-PCNL sepsis is best predicted by stone or renal-pelvic culture.
- Venous gas embolism → position head-down, right side up.