Complete clearance of all infection-related stone by primary PCNL or combined therapy.

Assessment of the stone:

The aim of surgery in this scenario is to completely clear the pelvic stone and as much of the peripheral stone volume as possible.

The peripheral calculi usually require two or even three separate “Target” or “Y” punctures for clearance.

The surgeon should commence by creating a primary track that will give access for removal of the majority of the stone bulk, including the central stone mass. If it is anticipated that the procedure may not be completed in one session, subsequent punctures should target those calyces with the poorest drainage. Further management of residual calculi will then be ESWL, PCNL, FURS or observation.

If the initial PCNL puncture aspirates frank pus, a nephrostomy should be inserted and the PCNL abandoned. The PCNL can be safely re-attempted following 5–7 days of percutaneous drainage and parental antibiotics. Failure to observe this precaution can result in the rapid development of septic shock.

It is usually easy to place the tip of the needle on the outer edge of a staghorn calculus, as the stone is big, easy to see on imaging, and can be felt when the needle tip contacts the stone. However, it is often difficult or impossible to thread a guide wire into the collecting system between the stone and the calyceal wall.

The surgeon has to establish a stable guide wire before being able to dilate a track onto the stone. This situation commonly arises when the needle hits the outer edge of the calyceal calculus. Little or no contrast can be aspirated and it is not possible to pass the tip of the guide wire between the stone and the collecting system.

This suggests that the needle is hitting the stone “end on”. The surgeon must make a new puncture, with the aim of placing the needle tip just proximal to the outer end parallel to and along the side of the neck of the calyceal extension of the calculus. The intention is for the needle to slide between the stone and the collecting system. Occasionally, gentle “over distension” by retrograde injection of contrast or saline through the RGC may separate and create some space between the stone and the calyceal wall. However, one must exercise caution to avoid contrast extravasation and sepsis from forcing infected urine into the renal tissue.

If this is successful and the wire passes between the stone and the collecting system, a track can be dilated onto the tip of the stone, which is then excavated with the sonotrode.

If one cannot advance sufficient guide wire to obtain a stable track, the straight wire should be removed and exchanged for a J wire.

As the J wire is advanced, its rounded leading edge will often “roll” between the stone and calyceal wall to create a space sufficient to introduce enough guide wire into the kidney for dilatation of the track.

In the event of the above procedures failing to establish a stable length of guide wire within the collecting system for dilatation, the “retroperitoneal guide wire” (RPGW) technique can be employed.

After all attempts to introduce a guide wire into the collecting system have failed, re-puncture and advance the nephrostomy needle to touch the outer edge of the calyceal extension of the calculus.

Gently angle the needle and continue to pass it through the renal substance until it exits into the retroperitoneum. Having felt the stone by crepitus with the puncture, the needle and subsequently the guide wire will be in direct contact with the calculus.

After the needle has been advanced into the retroperitoneum, the needle and stylet are removed, leaving only the sheath in situ. A floppy-tipped hydrophilic guide wire is then introduced into the needle sheath and advanced so that it passes the stone and coils in the retroperitoneum.

This coiling gives the wire stability and allows the surgeon to dilate directly onto the stone.

By using one of the above techniques, the surgeon has established a stable guide wire for track dilatation. Now there is a guide wire adjacent to the calculus, the surgeon can make a track to the outer edge of the kidney. However, there will still be insufficient space between the stone and the collecting system to allow safe insertion of an Amplatz sheath or the nephroscope. A nephrotomy must now be developed so that the surgeon can see the calculus and create a cavity sufficient for the Amplatz sheath to safely enter the kidney.

Following the establishment of a guide wire adjacent to the stone using one of the above techniques, a 26 Fr dilator (I use a single stage) is advanced under II monitoring over the guide wire until the tip of the dilator is touching the calculus.

This is determined by screening, Parallax and the sensation of crepitus when the dilator tip contacts the stone.

The dilator should not be advanced further. Forcing the dilator between the calculus and the kidney will split the parenchyma and cause bleeding.

An Amplatz sheath is passed over the dilator until its leading edge is flush with the shoulder of the dilator. This is confirmed on II and the proximal dilator shaft marker if using the Webb dilator If the dilator is barely in the kidney, reverse the Amplatz sheath so the flat or non oblique end abuts the renal capsule.

An experienced assistant is required because they must maintain the Amplatz sheath precisely after removal of the dilator. A nephroscope is passed through the Amplatz sheath alongside the guide wire.

All clots within the Amplatz sheath are removed using alligator forceps.

The blunt tips of the alligator forceps are gently inserted alongside the guide wire through the parenchyma and opened, to separate the parenchyma, similar to creating an open nephrotomy. This is continued until the stone is visible.

When the stone is visible, it is safe to gently advance the nephroscope (but not the Amplatz sheath), to excavate a sufficient volume of stone using a sonotrode to create a cavity large enough for the safe advancement of the Amplatz sheath, either under direct vision or by reintroducing the dilator into the calyx.

At this stage, it is helpful to establish a guide wire into the collecting system. This will stabilise the track and enable the surgeon to introduce larger dilators and Amplatz sheaths for more efficient removal of the calculus.

By the time the surgeon has excavated enough stone for the Amplatz sheath to enter the calyx, it is usually possible to thread a second guide wire under vision between the calyceal wall and the stone, parallel to both of them, until the wire enters the renal pelvis and if fortunate, goes down the ureter.

A useful aid for determining the direction of the renal pelvis is the retrograde infusion of methylene blue solution.

A pre-prepared solution of normal saline and methylene blue is infused through the retrograde catheter by the assistant.

The surgeon is directed by the blue flushes to the space between the stone and calyceal wall, which indicates the direction in which to pass the guide wire through the nephroscope, or further excavate with the sonotrode. As the stone bulk is reduced, the methylene blue infusion becomes more profuse and the path for the guide wire clearer.

As soon as the surgeon reaches the renal pelvis, a UGW should be established.

Before introducing the UGW from the bladder end of the RGC, the assistant must remove the minimum volume extension tubing from the Leur lock. The assistant then introduces the floppy end of a straight hydrophilic guide wire into the ureteric catheter and threads it towards the kidney.

The surgeon identifies the wire endoscopically as it enters the pelvis.

It can be confusing as to whether the wire seen in the pelvis is the nephrostomy or the retrograde wire.

If the assistant “wiggles” the ureteric wire up and down, this manoeuvre identifies the UGW. If not, II screening will assist the surgeon in identifying the correct wire.

Once the UGW is identified, it is grasped by the surgeon and extracted through the Amplatz sheath. Both ends of the UGW are then grasped with artery forceps, which are separately fixed to the drapes at either end.

Now the PNCL becomes straightforward and safe as the guide wire cannot be displaced. It becomes now a simple procedure for the surgeon to upsize the nephrostomy track size to 28 or 32 Fr over the UGW. The larger sheath size greatly facilitates flushing, irrigation, vision and stone removal.

If the stone is hard and large, it is usually more efficient at this stage to exchange the ultrasonic lithotrite for the pneumatic lithoclast.

The PCNL should proceed through this primary track until all visible stone has been cleared.

Once this is achieved, the surgeon must assess the progress of the procedure.

It is generally accepted that even an uncomplicated PCNL should not continue in excess of 2 h of nephroscopy.

After this period, the incidence of blood loss, infection, patient instability and “TUR syndrome” increases significantly. It is always acceptable to place a small “Cope” nephrostomy and complete the PCNL safely at a later date.

Therefore, if more than 2 h has elapsed or the patient is unstable, a nephrostomy should be inserted and the procedure terminated.

If the stone along the primary track is cleared, the patient is stable, and less than 2 h have elapsed, the PCNL may continue, usually requiring two or more separate targeted nephrostomies.

The existing Amplatz sheath should be left in situ.

This tamponades the existing track and fixes the kidney, making further punctures easier. The sheath also acts as an excellent venting drain for blood, irrigant and stone fragments during PCNL through other calyces. Having punctured a secondary calyx, a modified “calyx to calyx UGW” can be established, which provides increased stability for the subsequent dilatations.

I usually find that the primary or initial track is the best site for the nephrostomy at the end of the PCNL. Before placing the final nephrostomy tube, the initial track should be reinspected. In most cases, copious stone and blood clot will be in the renal pelvis, having fallen centrally during clearing of the secondary stone extensions. This debris must be cleared before final imaging and nephrostomy insertion.

The needle track should be aligned parallel to the axis of the targeted calyx.

The surgeon will know the needle is on the targeted stone by the sensation of crepitus. Due to the existing Amplatz sheath draining the kidney, it is not usually possible to inject sufficient contrast into the targeted calyx to assist with the secondary target puncture.

Following the needle puncture, a straight floppy-tipped hydrophilic guide wire is threaded through the needle sheath, past the stone and into the renal pelvis.

The guide wire is extracted from the original nephrostomy, both ends are clamped, to create a modified UGW, from calyx to calyx.

The wire into the targeted calyx is now stable, and it is safe to dilate onto the stone. This secondary UGW is not essential, but if it can be created, it is very useful for the puncture and subsequent clearance of the stone fragments from the calyx and renal pelvis.

The original sheath provides excellent drainage and acts as a low pressure vent for stone fragments and clots, as the PCNL continues.

Once the targeted calyx is endoscopically clear, the renal pelvis should be re-endoscoped through the primary sheath. Considerable debris will usually have passed from the targeted calyx.

I find that after extensive ultrasonic or ballistic lithotripsy that there are often multiple scattered fine 2–3 mm stone fragments that are too numerous, small or hidden in clot, to extract manually. These can be cleared very effectively by a saline flush through single or multiple Amplatz sheaths. Attach a medium-sized infant feeding tube (IFT) to a 20 cc syringe of normal saline. Introduce the tip of the IFT deep to the sheath and flush gently. As the sheath is a wide and open system, stone fragments and clot readily flush out without increasing intrarenal pressure.

If the patient is stable and there is time, further similar punctures can be made. If not, a “Cope” loop nephrostomy is inserted via the original Amplatz sheath, and the secondary access sheaths removed. Nephrostomies are not necessary for the secondary punctures.