Percutaneous nephrolithotomy

• Urolithiasis discussion 

Relative indications

• Stone > 2 cm, or lower pole stone > 1 cm
• Staghorn stones
• Better stone-free rate is important for struvite stones which tend to recur (infection-based)
• Cannot gain retrograde access for URS (abnormal anatomy, urinary diversion, transplant kidney, etc)
• Similarly - calyceal diverticulum stones that would be difficult to treat with URS

Contraindications

• Pregnancy
• UTI
• Uncorrected coagulopathy
• Cannot access kidney safely (e.g. retrorenal bowel)
• Cannot appropriately position (e.g. obesity/COPD such that cannot tolerate prone positioning)
• Relative - large skin-to-stone distance (should be < 15 cm)

Pre-op evaluation

• Non-con CT to assess anatomy of kidney and surrounding organs
• If evidence of renal atrophy, consider Mag3 to evaluate residual function (e.g. nephrectomy may make more sense)
• CBC/coags
• UCx
• Patient selection - can they tolerate prone positioning, what are their other co-morbidities, etc
• Peri-op antibiotics - amp/gent?

Steps

1. Positioning - prone split-leg
1. Can do many different positions - oblique prone, supine +/- flank elevation etc
2. Access ureter retrograde, deploy ureteral access sheath
3. Maneuver ureteroscope to target calyx (posterior); may need to clear stone out of the way
4. Inject contrast to perform nephrostogram
5. Percutaneous access with 18ga Chiba needle (see below)
6. Place Amplatz super stiff wire through needle 
7. Skin incision
8. Dual lumen to place second wire (Sensor wire)
9. Assemble nephroscope
10. Balloon dilation over Amplatz super stiff wire up to 30 Fr (or desired size)
1. Do not dilate into infundibulum/pelvis
11. Sheath placement
12. Place nephroscope and treat stone
13. Place tubes (if any)
1. Ureteral stent - antegrade or retrograde
2. Nephrostomy tube - can use 18-20 Fr Council tip over wire, with 2-3 cc water in balloon
1. Perform nephrostogram to confirm correct positioning
2. Can use 50:50 contrast in balloon but this can create artifact in post-op CT

Getting percutaneous access

• Percutaneous access can be obtained via US, CT, or fluoroscopic guidance
• Can have access placed pre-PCNL by IR, or perform at the time of PCNL
• Ultrasound access reduce radiation exposure and can visualize adjacent tissue like the diaphragm, spleen, bowel
• Use an 18 gauge Chiba needle (can place wires through needle)
• Access posterior calyx posterolaterally (Brodel's avascular plane; avoid intraperitoneal injury)
• Upper pole access is best suited for complete staghorn stones, complex lower pole stones or large proximal ureteral stones. Upper pole access is associated with higher complication rate compared to lower pole (pleural injury/pneumothorax).
• Perform during end-expiration to avoid lung injury; try for infracostal access
• CXR afterwards to check for pneumothorax unless below 12th rib/pleural reflection
• Access strategies - 'bullseye' vs. 'triangulation'
• Videos
• Fluoroscopic access - bullseye
• Triangulation technique
• Bullseye technique
• Bullseye technique 2
• Bullseye
• Pre-mark needle with expected skin to stone distance
• C arm at 30 degrees: identify posterior calyx and make puncture with needle in line with C arm (needle should look like a point on fluoroscopy)
• C arm to 0 degrees: advance needle in same plane until the calyx is punctured
• Triangulate
• C arm at 0 degrees: mark posterior calyx (point A)
• C arm at 30 degrees: mark posterior calyx again (point B)
• Distance between point A and B is about 1/2 of skin to stone distance/puncture length
• Make equilateral triangle with point C
• Puncture through point C, making multiple C arm adjustments (rotate between 0 and 30 degrees) to guide puncture to calyx

Different size sheaths

• Smaller sheath size advantage - decreased blood loss, decreased pain
• Disadvantages - poor irrigation/no suction, longer operation times

Different stone treatment modalities 

• Ultrasonic
• Intermittent shockwave
• Pneumatic
• Many different combinations, e.g.
• Shock pulse/Cyberwand - shockwave + ultrasonic (Stanford)
• BosSci Trilogy - ultrasound + pneumatic

Different tube/exit strategies

• Neph tube + stent (also leave Foley overnight for max drainage)
• Tubeless (no neph tube; + stent)
• Indications for tubeless PCNL: no intraop hemorrhage, no collecting system injury, normal renal function, normal Plt and coags, stone free
• Totally tubeless, dude

Complications

• Bleeding (5% major hemorrhage)
• Pseudoaneurysm, AV fistula
• Management of hemorrhage
• If puncture artery (pumping blood) or vein (guidewire into IVC) during stick - can withdraw needle and re-establish access
• During dilation - tamponade with larger sheath, place nephrostomy tube, abort
• After sheath removal - manual compression, insert council tip catheter and inflate balloon in parenchyma, -> IR for selective embolization
• Through nephrostomy - clamp to promote clotting, -> IR for embolization
• After nephrostomy removal - replace nephrostomy tube, -> IR to embolize
• Pneumothorax (10% of supracostal punctures)
• Other organ injury (0.5% bowel injury)
• Management of colon injury (confirmed by contrast in bowel during nephrostogram):
• Retract nephrostomy tube into the bowel lumen to drain bowel for 7-10 days
• Place ureteral stent to drain kidney (idea is maximal drainage to prevent fistula)
• Low residue diet, antibiotics
• Abort procedure
• Management of duodenal perforation
• NGT and bowel rest/TPN to drain bowel
• Nephrostomy to drain kidney
• Abort procedure
• Infection (~50% get febrile post-op; 1% get septic)
• Good table at bottom of article with complications/management here