Percutaneous Nephrolithotomy (PCNL)

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.

Preoperative Evaluation

• Non-contrast CT is the key study — it maps the stone burden and flags complicating anatomy: hepatosplenomegaly, a retrorenal colon (< 1%, commoner after jejunoileal bypass or spinal-cord injury), and the diaphragm, and it serves as a virtual roadmap for access. IVP/retrograde pyelography still helps define a calyceal diverticulum's communication with the collecting system.
• Urine culture in every patient (especially neurogenic bladder or urinary diversion, which are often colonised). Even with a negative culture, give a 1-week course of a broad-spectrum antibiotic before PCNL because the calculi themselves may harbour bacteria — a controlled trial (Mariappan) showed 1 week of ciprofloxacin significantly cuts upper-tract infection and urosepsis regardless of culture. A cephalosporin covers the commonest secondary organism (S. epidermidis), and high-risk patients get ampicillin + gentamicin. (This is separate from the ≤ 24 h perioperative prophylaxis below.)

Positioning and Setup

• Flat prone with a split-leg modification is preferred — it keeps retrograde urethral access available throughout (supine PCNL is an alternative with easier ventilation but harder upper-pole access). Elevate the treated side ~30° on foam to bring the posterior calyces vertical.
• Pad meticulously on egg-crate foam (keep the head level with the torso to protect the neck); maintain the axillary angle < 90° (brachial-plexus protection) and the elbow > 90°, and abduct both legs ~45°.
• The prone view is reversed: the trigone and ureteric orifices sit "at the top" of the screen, and the surgeon's right is the patient's right — run irrigation to clear all air from the cystoscope first (air in the bladder hides the orifices). Two equipment tables are used: a lower (retrograde cystoscopy) and an upper (PCNL) table.

Percutaneous Access

The preferred entry is posteriorly, along the calyceal axis, through the papilla (Brödel's relatively avascular line). The kidney's axis is oblique and dorsally inclined (the upper pole more medial and posterior), so a posterior calyx lies ~30° off the vertical when the patient is prone, with the poles offset ~10° cranially/caudally — the anatomic basis for the C-arm angulation below. 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).

Puncture-site rules: enter through the papilla or fornix (never the infundibulum or pelvis directly — higher vascular-injury and tube-dislodgement risk); stay medial to the posterior axillary line (the colon lies anterolateral); avoid a very medial puncture (paraspinal muscle → pain); and on a supracostal puncture stay off the rib (intercostal nerve/vessels).

Puncture Technique

After retrograde opacification (a 5–6-Fr open-ended ureteral catheter, or a 7-Fr occlusion balloon for a large stone or dilated ureter), a biplanar C-arm in low-dose, pulsed, collimated mode guides an 18-gauge diamond-tip needle by one of two methods:

• Eye of the needle — align the target calyx, needle tip, and hub into a bull's-eye on the AP view (looking "down the needle"), advance, then rotate the C-arm ~90° (vertical) to judge depth; aspirating urine confirms entry.
• Triangulation — the skin puncture is ~1 cm inferior and 1 cm medial to the tip of the 12th rib; make left/right adjustments on the AP view and up/down adjustments on the oblique view, keeping one plane fixed while adjusting the other. Suspend respiration in full expiration, confirm no gas-filled colon on at least one view, and rest the forearm on the torso to stabilise. Avoid manipulating the needle once in the parenchyma (it displaces the kidney).
• Ultrasound guidance (a 2.5–3.5 MHz convex probe) is an alternative that gives no radiation, shows the intervening bowel/organs, and (with Doppler) the vessels. Scan the kidney's long axis first to map the calyces, then target a posterior calyx through the papilla by the shortest tract. Its learning curve is easier in a dilated (or artificially hydronephrotic) system, a low BMI, and no prior renal surgery — good starting cases.

Wires and Tract Dilation

1. Wires — pass a hydrophilic nitinol glidewire and direct it down the ureter (a 5-Fr Cobra/Kumpe angiographic catheter steers it toward the UPJ), then exchange for a stiff Amplatz super-stiff working wire (a lubricious glidewire must not be left as the working wire). Place a safety wire through an 8/10-Fr coaxial dilator and clamp it to the drape before any dilation. If the wire will not pass down the ureter, secure access after dilation by advancing a long (260-cm) exchange wire retrograde up the ureteral catheter and grasping it out through the working sheath — through-and-through access that guards against inadvertent loss of the tract.
2. Dilate over the stiff wire under fluoroscopy — balloon dilation causes less bleeding than sequential Amplatz or metal telescoping dilators (radial vs shearing force). Position a 30-Fr balloon just inside the calyx and inflate it with a LeVeen syringe until any "waist" resolves — ~18 atm with a standard balloon, or 20–30 atm with a 30-atm-rated balloon (a persistent waist = perirenal scar — use a 4.5-mm fascial incising needle). Advance a 30-Fr Amplatz sheath over the balloon with a rotating motion — do not over-advance (the commonest serious access error).
3. Morbid obesity — have a 20-cm extra-long Amplatz sheath and nephroscope available (skin-to-stone distance may exceed standard lengths).

Special Access Situations

• Supracostal / upper-pole — aligns with the renal pelvis and UPJ (ideal for proximal-ureteric stones, staghorns, or a planned endopyelotomy) but risks the pleura; avoid puncturing above the 11th rib and stay in the lateral half of the rib to remain extrapleural, use an Amplatz sheath (mandatory to limit hydrothorax) and keep it in the kidney throughout, and screen the chest at the end. The overall supracostal complication rate is ~16% (vs ~4.5% subcostal), and is far higher for a supra-11th (34.6%) than a supra-12th (9.7%) puncture — the lung base rises two interspaces (moves cranially, away from the flank) on full expiration, so puncture then. Leave a JJ stent for all supracostal tracts.
• Calyceal diverticulum — a single-stage direct (preferably infracostal) puncture onto the stone with a J-tipped removable-core wire coiled in the cavity; use 11-Fr alligator forceps to dilate up to the diverticulum. Find the infundibular communication (methylene-blue/indigo-carmine retrograde irrigation helps), balloon-dilate it and leave a tube; if none is found, fulgurate the cavity with a rollerball.
• Multiple access / Y-puncture — a second tract is needed for a stone > 2 cm not reachable by a rigid instrument, or any stone not reachable by a flexible one. A Y-puncture angles a second tract off the first through the same skin incision.
• Miniaturisation — Miniperc (sheath ≤ 20 Fr), Ultra-miniperc (≤ 13 Fr), and Microperc (a 4.85-Fr needle carrying a 200-µm laser and microoptics): less bleeding/pain but poorer visualisation and instrument choice, best reserved for smaller/limited stone burden.

Supine PCNL and ECIRS

Supine PCNL, and its refined form ECIRS (Endoscopic Combined IntraRenal Surgery), treat the stone through a single antegrade tract while a retrograde flexible ureteroscope works simultaneously — a one-step combined approach that gives high stone-free rates and low-grade complications, often through a single tract in under ~70 minutes.

• Position — Galdakao-Modified Supine Valdivia (GMSV): supine at the edge of the operated side, the flank lifted 20–30° on jelly pillows under the shoulder and gluteus; the contralateral arm abducted < 90° and the ipsilateral arm across the chest; the legs in a modified lithotomy (ipsilateral slightly abducted/extended, contralateral lifted/flexed) to allow retrograde access. Reference lines — the posterior axillary line, iliac crest, and 12th rib — mark the working area.
• Retrograde first — a semirigid then flexible ureteroscope maps the dynamic anatomy, places a guidewire, takes a urine culture, and performs retrograde pyelography; the target calyx (usually an inferior-posterior one) is filled with contrast, and its scope tip can be marked by ultrasound.
• Combined puncture — an ultrasound-assisted, fluoroscopy-guided, Endovision-checked puncture through the papilla (the retrograde scope confirms needle entry), establishing a through-and-through guidewire ("kebab", out the urethral meatus) that eliminates access loss and steadies the kidney hypermobility typical of the supine position.
• Low intrarenal pressure — the ureteroscope in the ureter acts as an occlusion balloon, and the near-horizontal Amplatz sheath (a 4–6-Fr difference to the nephroscope) drains freely, keeping intrarenal pressure — and the infection / fornix-rupture risk — low, usually without a ureteral access sheath.
• Stone clearance — dilate to an Amplatz sheath (24-Fr standard, 18-Fr rigid nephroscope) and fragment as in prone PCNL; the retrograde flexible scope handles ureteral, parallel-calyx, or tight-infundibulum stones and can move fragments to the sheath ("pass-the-ball").
• Exit — a double-J with a string plus a small closed 8-Fr pyelostomy (pyelostomy out on POD1; the stent and catheter at ~48 h) — a "mini-intubated" exit that keeps pressure low and drains readily if fever or pain develops.
• Trade-offs vs prone — supine eases ventilation and simultaneous retrograde access and avoids repositioning, but the kidney is more mobile and cavities can collapse (offset by the through-and-through wire and full-inspiration during puncture); upper-pole access is harder. Prone and supine give comparable outcomes — the choice is surgeon preference.

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.

Nephroscopy and Stone Extraction

• Once the sheath is in, leave the balloon inflated for tamponade until the nephroscope is loaded — removing it early lets clots form that trap stones and hide fragments. Introduce a 24-Fr rigid nephroscope with dual saline inflow; the retrograde ureteral catheter stays in to partly occlude the ureter and limit fragment migration past the UPJ.
• Small fragments (< 1 cm) are seized with a two-pronged non-toothed grasper and drawn out through the sheath; a soft nitinol Perc NCircle basket on a rigid shaft reaches stones a rigid grasper cannot. (Avoid three-pronged rigid graspers — the prongs splay out of view and can tear the collecting system.)
• After clearing the visible burden, switch to a flexible scope with fluoroscopy to survey every calyx and fragment any residual stone (Ho:YAG) to a basketable size.

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.

• Confirm clearance first — with visual inspection and high-magnification fluoroscopy, 100% of stones > 4 mm should be identified and cleared; withdraw the ureteral catheter and inject antegrade contrast to confirm ureteral patency (antegrade ureteroscopy for any ureteric fragment).
• A double-J stent is often preferred over a nephrostomy tube (easier postoperative management and faster discharge — only a voiding trial is needed), especially for a high tract above the 12th rib; a Foley keeps intrarenal pressure low to reduce bleeding. Reserve a nephrostomy tube for a planned second look, significant bleeding, or perforation.
• Close by infiltrating the costal nerves and incision with 0.5% Marcaine (± epinephrine), then absorbable suture and topical skin glue. For a supracostal tract, remove the sheath in forced expiration.

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 — postoperative fever affects ~25% but frank sepsis only 0.3–2.5%; 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). If purulent urine is met on access, do not dilate — place a nephrostomy, culture, and treat.
• 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, 4–16% with supracostal puncture — minimise by puncturing in end-expiration); colon injury (< 1%; 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.

Postoperative Care

• A chest x-ray if the access was above the 12th rib; the Foley stays overnight with a voiding trial the next morning.
• Discharge stented patients on an alpha-blocker, with a KUB before stent removal at ~1 week. Discuss stone composition — for a struvite stone, get a CT at 3 months to detect residual fragments (and eradicate infection).

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.