Dr. Manoj Monga presented “Controversies in Percutaneous Nephrolithotomy” at the 26th Annual Perspectives in Urology: Point-Counterpoint, November 10, 2017 in Scottsdale, AZ

How to cite: Monga, Manoj “Controversies in Percutaneous Nephrolithotomy” November 10, 2017. Accessed Aug 2020. https://grandroundsinurology.com/controversies-percutaneous-nephrolithotomy/


Dr. Manoj Monga, MD, discusses the controversies in PCNL in terms of use of antibiotics; endoscopic-guided access; whether it be prone or supine; which calyx to access; whether to use a small sheath or a large sheath; and what type of tube to leave at the end of the procedure.

Controversies in Percutaneous Nephrolithotomy


The topic is Percutaneous Nephrolithotomy.  That’s a procedure we do form the flank through a 1 cm incision for large stones, specifically for stones bigger than 15 mm.  What we will be doing in the shirt talk will be covering some of the controversies in terms of use of antibiotics; endoscopic-guided access; whether it be prone or supine; which calyx to access; whether to use a small sheath or a large sheath; and what type of tube to leave at the end of the procedure.

One more question for the majority in the room who are urologists, how many of you are currently doing PCNLs?  Wonderful. So the majority of people are doing PCNLs, hopefully this will provide some tips and tricks in terms of how to obtain the best outcomes.

We’ll start out with a few questions.  The first would be for this patient here, with the large lower pile stone, another secondary stone here in the middle calyx, which of the calyxes do you think you would prefer to go to, this one, this one, or this one to get your percutaneous access?

So we see a fairly even split between the three different approaches.  I would say in this situation, probably one in three would be the choice that most people would choose.  The challenge with option 2, the middle calyx is no one would access this stone here, it’s going to be a bit of a challenge to then torque down to the lower pole to get the bulk of the stone.

You’ll hear in my talk that traditionally we will go with the upper pole stick.  And upper pole stick will give us the best angle down, onto the upper pole, the pelvis, the lower pole.  You can see how all that’s a fairly straight shot, and it will also give us a good angle down the ureter.  To access this middle calyx here, we will be anticipating that we would need a flexible nephroscope to be able to get that stone out with a basket.  

What’s unique about this situation and this is something that you don’t typically know at the start of the procedure because now we no longer get a contrast enhanced image.  We’re relying on non-contrast CT.  This IVP shows us that the – – is relatively narrow, so perhaps some of you had concerns that if you access the upper calyx, will you be able to dilate or get through with your scope in at the lower calyx to get the stone.  And that might be why a certain number of patients chose option 3, a direct puncture under the lower pole.  As you’ll learn a little bit later in the talk, typically the upper pole access is the optimal choice but sometimes that does need to be tailored based on the patient’s anatomy.

The next question will be managing complications.  Often talks will focus on the therapy, but we don’t talk enough about how do you recognize complications and how do you manage them.  So you’ll also hear a little later in my talk that I always go in the upper calyx most commonly a super costal approach.  We’ll discuss some of the outcomes we have with that.  But because of that I always get a chest X-ray in the recovery room.  One could argue if you’re using a lower pole access perhaps you could avoid the chest X-ray.  We get a chest X-ray in the recovery room and let’s say this patient was found to have this finding here in pneumothorax.  

I was hoping there would be a box here that mentions that the patient’s oxygen saturation is 95%.  It does, it’s up here, good.  Oxygen saturation is 95%, and he’s asymptomatic.  At this point what would you recommend for this patient?  Thoracentesis; a pigtail chest tube; a large bore chest tube; or observation.

As you’re answering this question I’ll mention that it’s relatively uncommon to see pneumothorax.  More commonly what we will see will be a hydrothorax or a hemothorax, so more commonly we will see blunting of the angle, perhaps in an effusion here, and that will be the more common situation as opposed to a pneumothorax which is about five or six years since I’ve seen a pneumothorax.

Observation is the right answer, so all of you or most of you keyed in on the fact that the patient was saturating well, was asymptomatic, and it’s a relatively small pneumothorax, we might give the patient some nasal cannula oxygen, but otherwise we’d observe them and perhaps repeat the chest X-ray in a day or two.

A pigtail chest tube versus a 22 French chest tube, those would typically be for a hydrothorax or hemothorax.  How do you know which of those two it is?  The first step was to look at the hemoglobin.  If there’s been a significant drop in the hemoglobin between the pre-op hemoglobin and the hemoglobin at the time where you get a chest X-ray and there’s an effusion, that will raise a suspicion that it’s probably a hemothorax, and you’re more likely going to skip the thoracentesis and go directly to a chest tube.  

When I trained we would have put in a larger bore chest tube to drain the hemothorax but the trauma literature now says that a small pigtail tube will actually work just as well as a larger bore chest tube.

The main thing is that it needs to be done quickly.  If one waits two or three days, observing the patient’s to see how they do, you will end up going down the path of a loculated collection, the tube doesn’t drain well, then the patient ends up needing a VATS procedure a week or two later to preserve their pulmonary function and their ability to expand their lung.  So treating an effusion quickly is important.  Now that doesn’t mean I drain every effusion, if it’s a smaller effusion, and I think it’s fluid, the hemoglobins remain stable, we will observe those patients with the hope that the fluid will be absorbed.  So really the critical thing on a chest X-ray postoperatively is looking at the hemoglobin to see whether you think it’s the hemothorax or a hydrothorax, a hemothorax we drain that day, a hydrothorax we might observe to see if it resolves by itself.

So 15 mm sounds small.  You’re probably thinking isn’t it supposed to be 20 mm, there’s a mistake.  I’ve dropped the criteria for performing or – – PCNL to 15 mm for a number of reasons.  The first reason is I think our technique has improved, and with improved technique, decreased risk of morbidity.  There’s also a stronger push now to better outcomes with the single procedures as opposed to multiple procedures with unfavorable outcomes that then eventually end with a PCNL.  In addition to that, the initial enthusiasm for ureteroscopy I think has waned.  At the AUA this year, Lingeman [phonetic] presented his data, Pearl [phonetic] presented her data, both of them showed that CT based follow-up for ureteroscopy for renal stones demonstrates that only 50% of patients are stone free.  So while there was a rapid uptake of ureteroscopy for medium to large stones in the kidney, the outcomes that we’re obtaining with the ureteroscopy are inferior to PCNL.  

PCNL now remains the mainstay of medium to large stones bigger than 15 mm.  Shockwaves still plays an important role for smaller stones.  It’s the treatment of choice for stones smaller than 15 mm as long as the stones aren’t too hard, Hounsfield is based on CT, not too deep, skin to stone distance based on CT.  And we use a lower threshold to consider ureteroscopy if the stone’s in the lower pole.

So to summarize, ureteroscopy plays a role for large and small stones in specific situations.  The reason why a larger stone might go this direction as opposed to this is primarily if they’re on anticoagulation, and because of their cardiac risk cannot come off that anticoagulation.  Or if there is pleura, spleen, liver, bowel in the way that prevents a safe access to the calyx that we think would be best.  Morbid obesity really is not a contraindication to PCNL.

Just out of interest, how many of you are measuring Hounsfield units?  Good.  Skin to stone distance?  Excellent.

There are some smaller stones where PCNL might be considered.  Specifically related to issues where it might be difficult to get a scope up the ureter, and similarly it might be difficult for stones to pass down the ureter such as ureteral stricture, urethral stricture BPH, UBJ obstruction or other anatomical anomalies might lead you to consider a PCNL for a smaller stone.

Why not do PCNL for everyone?  Ninety-five percent success rate sounds great.  Why not do it for smaller stones?  Unfortunately, it does carry morbidity, and the most serious risk is death.  Four out 1,000 patients will die because of septic complications associated with PCNL.

This risk is increasing, it’s gone from 3 out of 1,000 to 4 out of 1,000.  Why is it increasing?  Why can’t we get rid of this risk?  Part of it is because the urine culture does not predict what bacteria is going to kill the patient.  And if you treat the preoperative urine culture, it does not decrease the likelihood of sepsis and cannot be considered a reliable preemptive measurement.  Those patients at higher risk include those with bladder outlet obstruction, a positive pre-operative urine culture, or having an indwelling nephrostomy tube, or a ureteral stent.  

If the urine culture doesn’t predict who’s at risk, what does?  If you do a PCNL, you won’t consent to aspirate from the renal pelvis.  That will be more predictive of what bacteria are growing.  Or you can crush the stone up and send that for culture.  Because of this risk, the risk of death, urologists overprescribe compared to what the guidelines recommend.  But it’s important to know that guidelines are guidelines, and some of the statements are based on opinion, not on fact.  

The data used to develop the guidelines for antibiotic use related to PCNL ureteroscopy is not based on any studies that say that one day is better than five days or seven days.  Those studies unfortunately have yet not been performed.  So because of this, only about 10% of urologists use one day of antibiotics, either for ureteroscopy or PCNL.  The majority of urologists will use over a week of antibiotics.

Another challenge is the bacteria changing.  In purple we see those bacteria that when we were training we learned are associated with struvite stones are infectious stones.  Urea is producing organisms, Klebsiella, Pseudomonas, and Staph, what ones sees now is the most common type of stones defined in an infection stone are E. Coli and enterococcus.  So are changes in the types of bacteria, increasing antibiotic resistance.  It’s becoming a challenge to know how to prevent the risk of sepsis.

One approach people have taken is to give a week of antibiotics to all patients.  From Scotland we find that giving a week of cipro decreases the risk of a systemic inflammatory response syndromic compared to controlled.  

Similar study from India using Macrobid or Macrodantin.  It sterilizes the pelvic urine, decreases the chance of bacteria in the stone, decreases the risk of SIRS, and decreases the chance of having circulating serum endotox.  Perhaps a week of antibiotics is the best thing to do for anyone undergoing PCNL.  But then we worry about other issues, C. diff, increasing resistance, tendon issues if one uses the quinolones.  

We’ve reported on a study this year where we randomized patients who were considered at low risk to either receiving a week of antibiotics or not, and there is no advantage in this group to give one week of antibiotics prior to PCNL.  

So to summarize, it’s best probably to individualize the approach to antibiotics.  If the patient is at high risk, which I define as recurrent UTIs; an indwelling catheter, nephrostomy tube or stent; a neurogenic bladder; sterile pyuria; or other things that make you concerned that it’s a struvite stone.  If the stone looks heterogeneous on the CT scan when you look in the bone windows.  If the PH is high, if they’ve had ureas producing organisms in the past.  These would be the type of patients where we give one week of antibiotics prior to surgery, even if the urine culture’s negative.  Otherwise we typically use the 24 hour recommended in the guidelines.

We shift now to positioning the patient.  First I’ll describe our technique, and then we’ll talk about why we do it that way, why haven’t we gone supine, why haven’t we gone to a mini-perc.  These made by Steris, these leg adapters.  They’ll fit on any type of operating room table.  You don’t need a special table, just these adapters which are commonly used in orthopedics and other specialty so you operating room may have them.

Surgeon stands by the flank.  The assistant sits at the perineum.  If you’re in practice, this might be your partner who comes in for the 30 minutes that it takes to perform the access and then can leave while you’re doing the PCNL.  He or she can bill for the ureteroscopy while you bill for the PCNL.

So this will be a 63-year-old man, microhematuria workup, cysto was negative, hypertension, diabetes.  For the purposes of this course, just to fit in with the rest of the talk, let’s just say he’s been treated for prostate cancer and he’s on testosterone supplementation.

This is a large stone, 19 mm in the lower pole, relatively hard.  As you know, a lower pole stone bigger than 10 mm would be considered an appropriate candidate for PCNL.

These use, I don’t commonly use for planning my procedure, but I thought demonstrates nicely why the upper pole punctures the ideal puncture.  It also happens to show you how the pleural reflection in the ribs correlate with the position of the kidney in this patient, but the most important thing is you can appreciate the straight shot.  Everything’s in line, upper pole, pelvis, lower pole.  The goal is to reach as much of the stone with a region nephroscope because with a region nephroscope you can use the ultrasonic, you can remove the bulk of the stone, and rely less on lasering and getting out lots of little pieces with the basket.  

The most efficient approach is the approach that gives you the majority of stones accessible with the Regiscope in an ultrasonic.  This also gives you an idea of why lower pole really isn’t that great.  Because you’re trying to get on the tip of the papilla as you’ll see a little later.  That’s where the blood vessels are absent.  Less likely to have bleeding complications.  The tip of the papilla for this is here.  So that’s going to be a touch access.  Going here is going to be more of an angulated access through more parenchyma, increased torque, higher risk of bleeding with a lower pole puncture for this patient.

The patient goes to sleep on a gurney.  They then go prone.  Nothing’s done on the gurney, it’s all done in a prone position.  Women, rigid cystoscope to access the bladder, men flexible cystoscope.  The ureter orifice will be up top, and so it’s important to get all the air out of the tubing.  If you go in with air in the tubing, it will rise to the trigone to make it more difficult to find the ureteral orifice.

So in a prone position we’re performing cystoscopy, fine the – – in place so wire up to the kidney.  We then rotate the image.  Rotating the image will allow you to be oriented.  When you move your needle to the right, it will move to the right.  If you don’t do this then you’re working 90 degrees off from yourself and you’re doing a lot of this motion to try to figure out where is that needle.  

So placing the spine on top, allows you to be oriented in terms of your needle motion.  A sheath has been place here.  The assistant is not looking in with a flexible ureteroscope and picking a posterior upper pole calyx.  We know it’s upper pole, partly because of watching as we go in with a scope, but also because the scope is relatively straight.  Now sometimes the scope will be curved, and if the scope is curved but it’s still on the upper pole, at this point you angle the C arm.  So you know how the book say, all if due 30 degree angle to get to Brodel’s line?  You don’t necessarily need to do that for the upper calyx.  Usually you can be straight on.  But on occasion if you see that the scope is curved, that would be the patient where you start to angle, maybe 5 degrees, then 10 degrees, until the scope looks straight like this.  Once the scope looks straight, it’s at that point that you start advancing your needle.  

The needle is laid on top of the tip of the scope.   Now how do we know this is a posterior calyx?  Because of this air bubble.  The air bubble tells you that you’re accessing a posterior calyx as opposed to an anterior calyx.  Once the needle is laid on the tip of the scope, we then rotate it up to make a bull’s eye.  

Now with the bull’s eye, you’re looking down the bore of the needle.  At this point we start to advance.  Now you might say, well what’s this kind of vaguely radial pick here?  It’s a needle driver make by Cook that allows you to keep your fingers out of the field of use.  And it’s a lot easier to use than a hemostat or a needle driver.  It allows you to advance the needle without having a radiopacity such as your fingers in the field of view.  Once I’ve advanced about one or two inches, at that point we rotate the image again.  Rotating the image allows you to gauge the depth of the needle as it’s approaching the tip of the scope with the goal of seeing the needle as it enters.  

Once the needle has entered, we use a Benson wire, at tip-less basket to grab the wire, and then we pull the wire out so you have through and through access.  A 5-French open and a catheter’s then used to change it to a super stiff wire.  The Benson wire is important because it’s floppy, and I’ve had one patient where I’ve injured the ureter pulling a less floppy wire through from up to down.  So a Benson wire critical to be atraumatic as you pull the wire down the sheath.  The super stiff is important for dilation of the tract but you notice here now there’s only one wire.  You don’t need two wires because you have a hemostat on both ends, so this is now both your safety as well as your working wire.  

Tract dilation with the balloon, watching the sheath come in, everything done under vision as opposed to fluoroscopy?   So we’re decreasing fluoroscopy time and we’re being more accurate.  Instead of looking in and seeing fat because you’ve dilated too far, instead of looking and seeing parenchyma because you’ve dilated too shallow.  By watching you’ll be able to know that you’re in the collecting system and hopefully looking at stone as soon as you look in.

So decreased fluoro time, decreased secondary procedures because of an inaccurate access, decreased risk of bleeding that causes you to abort the procedure.

Because we’re entering at this point here.  The upper pole, posterior calyx, the tip of the papilla because we’re looking at the tip of the papilla as we enter.  Less likely to have vasculature that’s going to cause bleeding, and a risk of ending a procedure early.

So why not supine?  Why prone?  Many people have done supine for many years.  This is a 25 year experience of almost 1,000 patients.  Safe, very few complications, effective.  First we note that 34% are having simultaneous ureteroscopy.  Though I’m doing this 100% to get access, they’re doing this because they weren’t able to access the stone with the access they obtained in the supine position.  Ninety-one percent are in the lower calyx and we’ve talked a bit about why the upper calyx is advantageous as opposed to a lower calyx.

Dr. Smith has shown when he does CT scans in a prone and a supine position the length of the tract is longer.  A longer length of tract means that you’re advancing the needle further, so it’s more likely that you’re going to go off course and perhaps have an entry that’s not as ideal as it should be.  But more importantly a longer track is harder to manipulate your scope.  If you take three fingers and try to rotate your finger, no one ever does that, but I always try to get them to do it.  And then you take one finger, you’ll see that it’s a lot easier to maneuver the shorter the tract is.  Easier to maneuver, less torque.  Torque is what causes bleeding because as you torque the kidney, that tears the blood vessels and causes more bleeding.

You might say well, the reason we’re going supine is because our anesthesiologists are worried, they say they can’t ventilate the patient.  Peak airway pressure is less than 40 and you anesthesiologist will be able to ventilate the patient.  When one looks at supine, prone, or prone with the patient flexed, and you look at people who are thin, or people who are morbidly obese, it’s true, the peak airway pressure rise when you go from supine to prone, but even in the morbidly obese patient in the prone position, the peak airway pressure is less than 25.  So patients can be adequately ventilated in the prone position even if they’re morbidly obese.  Others say, well, there’s less risk of neurapraxia.  I’m less worried that the patient is going to have issues postoperatively because of positioning in their prone position.  

But we look at the number of pressure points here.  A supine PCNL is not supine, it’s modified lithotomy.  And you can see how there’s a lot of additional issues with regards to positioning, padding, and potential risk to nerves [phonetic] in this position compared to a prone.  

And lastly people say well what if the patient has a serious event, a cardiovascular or pulmonary event where we need to perform CPR.  Again, one would argue that you can’t really do that effectively in this position here.  

What about surgical outcomes?  Prone positions are used more commonly and have a shorter surgical time compared to supine.  Stone free rates are high prone compared to supine.  There may be some suggestion that bleeding will be higher in the prone position compared to a supine.

More importantly other studies meta-analyses of randomized trials say no difference in stone free rates, transfusions, complications, or hospital stay, and I always wonder to change there needs to be a compelling reason to change, unfortunately no compelling reason here for supine.

It’s important to be critical with our own outcomes, so we look back at our outcomes, 462 patients all supracostal, all upper calyx, all tubeless, and all endoscopic guided.  Campells [phonetic] will say supracostal puncture, your risk of pulmonary complications is about 15%.  It’s 3.2%.  Transfusion rates are 4%, all these were 30 French sheaths compares favorable with the mini-perc data.

Now I mentioned I don’t use that sagittal view.  These are the views that are most important to look at in planning your percutaneous access.  It allows you to look at the liver, the spleen, the bowel.  In this situation there is a pleural reflection that I might be worried about, this might be the type of patient where we don’t do upper pole puncture, we adjust our plans.

This calyx here, we’ll do the same exercise of which calyx would you choose?  Who would choose this calyx here?  Who would choose this calyx here?  Who would choose this calyx?  Who’s going to refer this patient?  So you want to go upper calyx.  The nice thing about this even though it’s a complex system, it’s a fairly broad infundibulum except for perhaps these ones here.  With an upper calyx one, we would probably go either to this one or this one. You might look at this and say, well, how are you going to get our scope up and do an endoscopic guided approach.  Just like a stent, we’ll dilate the collecting system, a stone will dilate the collecting system.  So typically once the wire goes up, we follow where the wire is to get our scope in to do an endoscopic guided puncture.  So far, knock on wood, there’s been a handful of patients where I’ve had to revert to a fluoroscopic guided as opposed to an endoscopic guided.  But at time to get up to here we might need to pass a wire and pass the scope over the wire to get it up to that upper pole calyx.

The supine folks say well, the other advantage of supine is you can do ureteroscopy and this is just to show that you can do that in the prone position also.  You already have your access sheet to gain your access.  This is a child where we did an endoscopic puncture, removed the bulk of the stone but there were some stone here that we couldn’t access through this angle.  And if you ask, well where is the stone usually after the PCNL that you can’t reach.  It relates to what the angle is between your sheath and the stone.  If this angle is acute, that’s the type of stone that’s going to be more challenging to reach through a single access, but you can typically access it through flexible endoscopy as opposed to doing a second puncture.  

So here one sees the flexed ureteroscope from below, treating the stones with the laser moving the fragments to here where then it can be basketed from above.

Another consideration is bilateral PCNL.  Should they be done at the same time or not?  Many proponents have said you can do bilateral PCNLs, but I always worry.  If you have a complication, if the patient has a drop in their hemoglobin, how do you know which kidney is bleeding?  There’s also been shown that just the act of putting a needle in the kidney decreased renal function in that kidney for about a week, so now you’re decreasing renal function in both kidneys for a week as opposed to just one at a time.  

Dr. Lingeman presented this year at the AUA, the risk of needing a blood transfusion 4.0 four-fold higher if you do simultaneous bilateral PCNL compared to if you do stage procedures.  So one of the proponents for doing bilateral is now saying maybe it’s not the best idea.  Maybe it is better to stage the procedures as opposed to doing simultaneous procedures.

So we wanted to talk then about size.  I mentioned our series there 4.3% transfusion rate, dilating to 30 French though it seems to make sense, smaller might be better.  How many people own a gun?  Okay.  So you may know that, okay, many.  You may know then that smaller caliber bullets actually cause more trauma than larger caliber bullets.  Now I’m not a gunman so correct me if I’m wrong.  So sometimes what you think in terms of size of hole doesn’t really correlate to the amount of damage.  

I’ll have to admit that we were one of the first back in the late 90s who thought that mini PCNL might make sense, and I used a ureteral balloon and an 18 French sheath over that ureteral balloon to perform some mini PCNLs.

But soon after that Pearl came out with a study in pigs where they dilated the tract to either 11 French or 30 French and saw no difference in the amount of trauma.  The amount of loss of parenchyma, the amount of scarring that occurs whether you do a mini-perc or a regular sized perc.

Now despite that mini-perc has caught on.  This would be the example of the type of patient treated by a mini-perc.

This will be the type of studies that are reported and first you note that the stone size is medium size stones.  We talked about how our cutoff is 15 mm, the bulk of the patients in these studies wouldn’t have been considered for PCNL.  So this makes sense if you don’t have access to Holmium laser.  If you consider that flex ureteroscopy is too expensive an option for our healthcare system which indeed it might be.  But a mini PCNL typically isn’t used for the larger – – stones.  

Why not consider min I PCNL?  Risk.  The risk of septic complications.  Higher intrarenal pelvic pressures at the start of the procedure, with fragmentation, and irrigation throughout the procedure.  

We instill E. coli into the renal pelvis, and then perform PCNL either to 10 French or 30 French.  Pressures were higher, the time above 30 mmHg were longer.  We found bacteria in the kidney in both because we were instilling E. coli.  But spleen, liver, blood cultures higher risk of that with a mini PCNL because of the higher intrarenal pressure, so your risk of a septic complication, the first thing we talked about, how do you prevent those deaths?  Use a 30 French sheath, don’t use an 11 or 12 French sheath.

Surgical outcomes inferior, stone free rates 78% versus 94% with a mini-perc.  Operative time longer.  So to summarize, standard PCNL I think is a good procedure, it’s a safe procedure, and there’s certain risk to consider with a mini PCNL.

Tubeless approach, 20 years ago Dr. Bellman was a visionary.  Since then 10 RCTs, over 600 patients.  No differences in blood loss.  

Eleven studies now in a Cochrane Review, decreased pain, decreased analgesia, decreased hospital stay.  We find – – shorter hospital stay with a tubeless, less pain, less narcotics.  

What’s unique about our study was everyone went tubeless.  You had bleeding, you had a perforation, you had residual stones, everyone went tubeless.  

You might ask well, residual stones, why are you taking the tube out?  As mentioned the residual stones are because of one or two reasons.  Either the patient bled and we couldn’t see the stone.  If the patient bled, I’d rather not redilate that tract.  He’s going to bleed again.  

Secondary reason would be we couldn’t access the stone because of the angle of the access.  I showed you on the slide how the angle between the sheath and the residual stone is what dictates whether you can get to it or not.  So if I go in that access again, I won’t be able to get the stone again, so I’d rather do a second ureteroscopy to get that residual stone than to do a second PCNL for those who do have residual stones.

So to summarize, an endoscopic-guided approach; prone position; upper calyx; supracostal–we find that 92% of the time a single puncture is all you need if you’re using the ureteroscope to guide your access; maximum-perc, 30 French; and tubeless for all patients.  Thank you.