Percutaneous nephrolithotomy

Operative visualisation

UrOops3D · UroRef · © Nity G

How to use this module. Play through the eleven steps, or use Back and Next. The Screen panel shows a schematic image intensifier view; the working wire is white and the safety wire teal. Open Cross-section to relate the path to the axial view. Try the error states to see what a bad line looks like.

Operative steps

1. Before the day Urine is cultured and any infection treated before the date, and antibiotic prophylaxis is given by local policy: a single dose where there are no risk factors, a course beforehand where there are (hydronephrosis, tube drainage, a complex stone burden, diabetes or recurrent infection).
2. Retrograde set-up In lithotomy a rigid (17 to 22 Fr) or flexible cystoscope passes a 0.035 inch PTFE or hybrid wire up the ureter, and a ureteric catheter follows it. A 5 to 6 Fr open-ended catheter is standard; a 7 Fr occlusion balloon catheter, its balloon inflated at the PUJ, stops fragments running down the ureter and distends the system. The catheter is taped to a 14 to 16 Fr Foley. Contrast diluted to about 30 to 50 per cent fills the pelvis without masking the stone; methylene blue, if added, makes the efflux obvious at puncture. Sizes and dilutions on this page are owner-supplied typical values.
3. CT planning The CT is read before the patient is positioned, and the posterior calyx that best lines up with the stone bulk is chosen. A lower-pole calyx serves a simple stone; a staghorn usually needs an upper-pole, often supracostal, tract. The skin-to-calyx line is then traced slice by slice, noting everything it crosses on the way: skin, fat, the lumbodorsal fascia and muscle before the kidney. The line must clear the pleura above and the colon laterally; where it does not, the calyx or the position changes now, at the console rather than in the flank. One well-aligned tract is the plan, because extra tracts and sheath torque are where the bleeding lives. The patient is then turned prone, every pressure point padded.
   where it bites: the line must clear the pleura above and the colon laterally before a needle moves.
4. Calyceal puncture An 18G needle, 15 to 20 cm, diamond or bevel tip (or a 21 or 22G Chiba first in a two-step technique), goes in under the C-arm. Bull's-eye: the arm is tilted until the hub and the tip overlap as one dot, and the needle is advanced down the beam; triangulation: 0 degrees for the mediolateral line, 20 to 30 degrees oblique for depth. Ultrasound is an alternative: a curvilinear 3.5 to 5 MHz probe with a needle guide and colour Doppler to keep off the interlobar vessels. The needle gives twice, at the lumbodorsal fascia and at the renal capsule, and its tip enters the calyx through the papilla, along the calyceal axis and the avascular line of Brodel.
   where it bites: puncturing the infundibulum or pelvis directly tears the interlobar vessels beside the calyx; the papilla is the avascular entry, the line of Brodel, and everything beside it bleeds.
5. Confirm access The stylet comes out and urine, contrast or blue drips from the hub. That efflux confirms the tip is inside the collecting system, and nothing is dilated until that confirmation exists.
6. Two wires A 0.035 inch hydrophilic angled-tip wire goes through the needle, and a 5 Fr angled catheter (Kumpe or Cobra) steers it through the infundibulum into the pelvis and down the ureter. It is exchanged for a very stiff working wire (Amplatz Super Stiff or Lunderquist) so the dilators track without buckling. An 8/10 Fr coaxial dilator over it lets a second, safety wire go down alongside, and the 10 Fr outer is then removed; the safety wire is clipped to the drape. Both wires lie down the ureter to the bladder, through and through if the retrograde route grabs one, or coiled in the pelvis or a distant calyx. In the animation the working wire is white and the safety wire teal, and each is labelled.
   where it bites: dilating over a single wire leaves no way back in if it is lost.
7. Tract dilation A 1 to 1.5 cm skin incision is made along the wire with a No. 11 blade, and the lumbodorsal fascia is opened with a fascial incising needle or scissors, because it is the hardest layer to dilate. An 8 Fr Teflon guide catheter stiffens the track. Amplatz dilators follow over it in 2 Fr steps, 10, 12, 14 and on to 28 or 30 Fr, each with a gentle rotating push along the wire axis and each advanced only until its tip reaches the calyx on screening. The skin-level depth mark is noted on the first dilator and every later one goes to the same mark. Alken metal dilators, balloon dilation, one-shot dilation and mini-PCNL tracts are the alternatives. The Dilation chip in the animation plays the balloon alternative: a balloon dilator over the working wire, its tip at the calyx, inflated at the tract until the waist at the fascia gives and the balloon is 30 Fr along its length with the sheath loaded on it; it is deflated and withdrawn once the sheath is seated. One technique or the other, never both.
   where it bites: a dilator driven past the calyx perforates the pelvis; a kinked wire sends it off track.
8. The sheath The Amplatz sheath (30 Fr; 24 to 34 Fr are available) is loaded on the last dilator and slid into the calyx, its position confirmed on the image; dilator and guide come out, leaving the sheath and both wires. The sheath is then both the working channel for the nephroscope and the tamponade for bleeding, which is why it stays in the kidney for the whole case.
9. Stone clearance The nephroscope passes down the sheath and the stone is fragmented, the pieces leaving through the sheath with irrigation. The sheath is angulated to reach neighbouring calyces rather than forced, because torque on a seated sheath tears parenchyma. Flexible nephroscopy at the end checks the calyces the rigid scope cannot reach before anything is called clear. The endpoint is a system that is clear on inspection; fragments left out of reach are booked for a staged second look rather than the tract being over-run.
10. Drainage At the end of clearance the choice is a nephrostomy tube, an antegrade JJ stent, or a tubeless exit in selected uncomplicated cases. The decision follows the field: bleeding, residual fragments or a perforated system earn a tube, because the tube drains, tamponades and marks the tract for a second look. A nephrostogram through the tube confirms position and documents drainage before the patient leaves the table. Whatever drains the kidney, the drain plan is written into the op note with its follow-up imaging, because a drain without a plan becomes a drain without an exit.

Complications and immediate saves

Trigger each of these live in the Animation tab, then read the save: the first move, the escalation trigger, and the line that goes in the op note.

FRCS viva questions

The examiner stems this scene prepares you for. Try to answer out loud first, then reveal, and learn the discriminator, the detail that turns a pass into a strong pass.

Evidence and guidance