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Indications / Contraindications
Indications
- PCNL (percutaneous nephrolithotomy) — stone removal requiring nephroscope access (24-30 Fr)
- Percutaneous endoscopy — nephroscopy, ureteral endoscopy
- Nephrostomy upsizing for thick or pyonephric drainage
- Second-stage nephrolithotomy after initial nephrostomy drainage
Target Access Size
PCNL requires 24-30 Fr Amplatz working sheath. Endoscopic procedures typically 14-20 Fr. Confirm with urology BEFORE dilating — know their scope size.
Contraindications
- Uncorrectable coagulopathy — risk of significant hemorrhage substantially higher with large-bore access than standard PCN
- Thin renal parenchyma — high rupture risk with large sheath dilation
- Active uncontrolled infection — dilate after antibiotic treatment and adequate drainage
SIR Bleeding Risk
Category 2–3. INR <1.5, Plt >50K. Type and screen required — hemorrhage risk 1-5% with large-bore access. Transfusion may be needed.
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Pre-Procedure Checklist
CT/KUB review. Confirm stone burden, calyceal anatomy, planned access calyx. PCNL access calyx selection is a collaborative decision with urology — lower pole vs upper pole based on stone location and nephroscope trajectory needed.
Retrorenal colon check. Review CT specifically for retrorenal colon position before ANY large-bore access attempt. Far more dangerous to perforate colon with a 30 Fr sheath than a 21G needle.
Confirm access sheath size needed with urology before starting. Know what nephroscope they're using and what Fr they need. Don't guess.
Blood type and screen. Required — significant hemorrhage risk with large-bore access.
Antibiotics. Ceftriaxone 1g IV or fluoroquinolone based on urine culture. Required — large-bore manipulation of collecting system has high bacteremia risk.
Anesthesia plan. General anesthesia often preferred — patient movement during dilation is dangerous. Discuss with urology. If two-stage (IR dilation → urology PCNL separate day), moderate sedation may be adequate for IR portion.
Verify existing access or plan new access simultaneously. Patient should have existing nephrostomy or new PCN placement planned as part of same procedure.
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Relevant Anatomy
Access Route
- Lower pole posterior calyx: Ideal for most PCNL access — below 12th rib, away from pleura, best trajectory for lower/mid ureteral stones
- Upper pole access: Required for upper pole/staghorn stones — above 12th rib risk of pleural transgression (below 11th rib = transpleural). Higher risk; chest tube may be needed.
- Large-bore dilation traverses a significantly larger channel of renal parenchyma vs standard PCN — higher risk of laceration of interlobar or arcuate vessels
- Brödel's avascular zone still applies — aim for posterior calyceal access
Danger Structures
- Interlobar/arcuate vessels: Large vessels at risk during 24-30 Fr dilation through renal parenchyma — most common source of significant hemorrhage
- Pleura (upper pole): Transpleural risk with above-12th-rib access
- Retrorenal colon: Check CT — far more dangerous with 30 Fr sheath than 21G needle
- Liver/Spleen: Right and left flank access respectively
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Technique
Default RadCall approach · share your own below
Supplies
Fluoroscopy (biplane or C-arm)
0.035" Amplatz super-stiff guidewire (safety wire)
Second working wire (0.035" Amplatz)
Balloon dilator (Nephromax 28-30 Fr) OR Alken telescoping metal dilators
30 Fr Amplatz peel-away working sheath
Serial dilators (8 → 28 Fr) if sequential method
Nephrostomy catheter (12-20 Fr for end-of-case drain)
Dilute contrast + generous syringes
ChloraPrep + sterile drape
1% lidocaine
Suture material
Dilation Method — Pick One
Balloon dilation (Nephromax): Faster. Inflate balloon under fluoroscopy to target Fr in one step. Hold 60-90 seconds. Good for straightforward tracts. — Sequential Alken dilators: More tactile. Telescope through each size 8 Fr → 30 Fr. Fluoroscopic confirmation at each step. Good for resistant tracts. Center preference/availability dependent. Learn one system well.
Steps
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Access confirmation
Use existing nephrostomy catheter or place new PCN access. Take nephrostogram to confirm catheter position and delineate collecting system anatomy.
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Safety wire placement
Place stiff Amplatz wire as safety wire — advance into ureter or deep into renal pelvis. This is your lifeline. If anything goes wrong during dilation, this wire maintains access.
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Two-wire technique
Place second Amplatz wire alongside safety wire into collecting system. This two-wire technique is non-negotiable for large-bore dilation — wire loss during 30 Fr dilation is a serious emergency. The second wire provides immediate backup.
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Balloon dilation method
Advance balloon dilator (Nephromax) over working wire. Inflate under fluoroscopy to target French size in one inflation. Confirm full expansion (hourglass deformity should efface as balloon reaches full size). Hold 60-90 seconds. Deflate and remove balloon.
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Sequential Alken dilator method (alternative)
Start at 8 Fr dilator, advance over working wire under fluoroscopy. Telescope through each size upward to 28-30 Fr. Confirm fluoroscopic position at each step. The Alken system provides more tactile feedback but is more time-consuming.
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Amplatz peel-away sheath
Advance 30 Fr peel-away sheath + dilator over working wire through dilated tract. Position tip in renal pelvis — confirm intrarenal with contrast injection. Remove dilator — sheath remains in collecting system as working portal for urology.
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Confirm and hand off to urology
Inject contrast through sheath to confirm intrarenal position and no significant extravasation. Transfer to urology for nephroscopy. OR: If staged procedure, leave a large-bore tube through sheath and peel away sheath — urology performs PCNL within 24-72h.
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Troubleshooting
Problem
Dilator buckles in retroperitoneal fat
Likely cause: Insufficient wire advancement, retroperitoneal fat resistance, or floppy wire.
Next step: Ensure Amplatz wire is maximally advanced — well into ureter or ideally bladder for maximum purchase. Manual counterpressure on the flank while advancing dilator. Confirm Amplatz super-stiff is being used (not standard guidewire). Consider 2-wire technique if not already placed.
Problem
Difficulty advancing sheath after dilation
Likely cause: Tract not fully open, skin/fascia adhesion, or wire kink.
Next step: One more pass with the largest dilator to fully open the pathway. Skin nick may need to be enlarged. Confirm wire is not kinked on fluoroscopy. For balloon method: try another inflation at same size.
Problem
Significant arterial hemorrhage during dilation
Likely cause: Interlobar or arcuate vessel laceration from large-bore dilation.
Next step: STOP advancing. Notify urology immediately. Tamponade by advancing a large-bore nephrostomy catheter through the tract (tamponades the tract). If massive hemorrhage: angiographic embolization (pseudoaneurysm or AV fistula). Have this plan predetermined — brief the team before starting.
Problem
Lost wire — both wires out
Likely cause: Inadvertent wire withdrawal during sheath/dilator exchanges.
Next step: CRITICAL EMERGENCY. The 30 Fr tract will close rapidly. Rapid new needle access under fluoroscopy/US. This is why the two-wire technique is non-negotiable — one wire is never enough backup during large-bore work. Losing both wires simultaneously with a large tract open is an operating room emergency.
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Complications
Immediate
- Hemorrhage (#1 serious complication — 1-5% requiring transfusion; pseudoaneurysm/AV fistula from large-bore dilation)
- Pleural transgression (upper pole access) — pneumothorax or hemothorax; chest tube may be needed
- Collecting system perforation — urinoma; usually managed with drainage
- Organ injury — liver, spleen, colon (retrorenal); rare but serious
- Loss of tract access — two wires both lost; OR emergency
Delayed (post-PCNL)
- Delayed hemorrhage — pseudoaneurysm or AV fistula presenting 1-3 weeks post-PCNL as gross hematuria; angiographic embolization
- Urinoma — from tract extravasation
- Tract infection — treat with antibiotics; may need repeat drainage
- Hematuria — expected post-PCNL; should progressively clear. Clot obstruction → nephroscopy or irrigation
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Post-Procedure Care
Two-Stage Protocol (IR dilation → Urology PCNL)
- Tube in place after dilation; urology performs PCNL within 24-72h
- Monitor Hgb post-dilation: check at 4-6h; transfusion per clinical status
- Hematuria: expected; should be pink-red → clearing over hours to days
Post-PCNL (Urology Handoff)
- Nephrostomy tube left in place (typically 12-20 Fr) for drainage — urology removes when cleared
- Monitor Hgb 24h post-PCNL
- Gross hematuria: track closely. Progressive clearing expected. Bright red with clots or dropping Hgb → CT angiography → embolization
- KUB or CT post-PCNL for stone clearance assessment
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Critical Pearls
✦
Two-wire technique is non-negotiable for large-bore dilation. Wire loss during 30 Fr dilation is a serious emergency — a tract that size closes fast and putting a new needle in that field is extremely difficult. One wire is never enough; use two.
✦
Amplatz super-stiff wire provides the rigidity needed to drive dilators through 3-4 cm of soft tissue and renal parenchyma. Standard guidewires buckle. Standard Amplatz (not super-stiff) may be inadequate for very obese patients or resistant tissue. Super-stiff is the minimum.
✦
Know the urology team's nephroscope size before you dilate. If they need 24 Fr and you dilate to 30 Fr, you've created excess parenchymal injury. If they need 30 Fr and you only went to 24 Fr, they'll need re-dilation. Communicate beforehand.
✦
Have blood typed and screened, not just ordered. The 1-5% hemorrhage rate requiring transfusion is not trivial. In an obese or difficult-to-access patient, that number climbs. Blood should be available, not just "on order."
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Balloon dilation vs sequential Alken: both work. Learn your center's system and be expert in one. Don't switch mid-case when things get difficult. The complication rate is similar between methods when performed by an experienced operator.
✦
Retrorenal colon check is mandatory before large-bore access. Present in ~10% of patients. Perforating the colon with a 30 Fr sheath causes fecaluria, severe sepsis, and very complicated management. Five seconds on CT to check is worth it every time.
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Access Sheath Sizing Reference
| Sheath Size | Use | Instrument | Notes |
|---|---|---|---|
| 11-13 Fr | Mini-PCNL | Mini-nephroscope | Growing adoption; less bleeding risk; smaller stones or selected cases |
| 14-16 Fr | Flexible ureteroscopy | Ureteroscope | Smaller tract, less bleeding risk |
| 20 Fr | Semi-rigid ureteroscopy | Ureteroscope | Moderate tract size |
| 24 Fr | Standard PCNL | Nephroscope | Most common PCNL access size |
| 26-28 Fr | Large nephroscope | Nephroscope + large basket | Standard PCNL for large/staghorn stones |
| 30 Fr | Max PCNL / staghorn | Nephroscope + lithotripsy | Upper limit; bleeding risk increases |
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References & Resources
Primary sources · Key data · Related procedures
Key Guidelines
- EAU guidelines on percutaneous nephrolithotomy (PCNL) access
- SIR quality improvement guidelines for PCN
Primary References
- Shaban A, Pristupa A. Percutaneous renal access for nephrolithiasis. Semin Intervent Radiol. 2011;28(4):416–423.
- Ramchandani P, Cardella JF, Grassi CJ, et al. Quality improvement guidelines for percutaneous nephrostomy. J Vasc Interv Radiol. 2003;14(9 Pt 2):S277–S281.
- Kekre NS, Gopalakrishnan GG. Percutaneous nephrolithotomy: Current status. Indian J Urol. 2009;25(1):15–21.