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In this interview, Thomas Chi, MD, discusses how he performs PCNL, explains why he uses ultrasound instead of fluoroscopy, and offers advice to urologists looking to gain more experience with the procedure.
Percutaneous nephrolithotomy (PCNL) offers a potentially shorter recovery time for patients but is a challenging procedure to perform. In this interview, Thomas Chi, MD, discusses how he performs PCNL, explains why he uses ultrasound instead of fluoroscopy, and offers advice to urologists looking to gain more experience with the procedure. Dr. Chi is associate professor, associate chair for clinical affairs, and Kutzmann Endowed Professor in Clinical Urology at the University of California, San Francisco. Dr. Chi was interviewed by Urology Times Editorial Consultant Stephen Y. Nakada, MD, the Uehling Professor and founding chairman of urology at the University of Wisconsin, Madison.
What are the indications for PCNL?
If you look at the guidelines, the indications for PCNL are any stone 2 cm to 2.5 cm or larger. We don’t have a lot of guidance for the medium-size stone (1 cm-2 cm). For those stones, I leave it up to the patient and discuss shock wave lithotripsy, ureteroscopy, and PCNL with them. I think the trade-off with PCNL is that even though it’s more invasive, patients recover a little faster and may return to work a little sooner. Some people like the idea of a nephrostomy tube for a short time versus a stent for a longer time.
Do you think patients prefer the percutaneous approach compared to a noninvasive approach?
I think a lot of patients come in with a preconceived notion, but I spend a lot of time describing a stent and the uncertainties associated with having to wear a stent and how much it may impact their life. When they weigh having the stent versus having a nephrostomy tube in the hospital for 1 or 2 days, I think a lot of people change their mind. My experience has been that patients in the short term may prefer a small nephrostomy tube for a day or two compared to a stent for a couple of weeks, but I don’t know that a lot of data exist to guide us either way.
Who do you think should do these procedures? Should it be any urologist versus specialized urologists? Should radiologists be involved?
It’s a complex answer. Every hospital system and practitioner has a different set-up, which makes the relationship between interventional radiology, their own training, and comfort different. PCNL certainly is a challenging procedure, but it’s probably because a lot of the approaches we have are a little bit difficult to learn. There’s a long learning curve to master fluoroscopy. That takes some level of comfort. I think that everybody should be doing PCNL if we can make the procedure easier and more facile on their hands. That way, patients will get the optimum procedure for the stone as opposed to avoiding a procedure because providers feel uncomfortable with it.
Next:Dr. Chi explains how he does a PCNLPlease take us through how you do a PCNL.
I trained with fluoroscopy, so I did traditional prone percutaneous nephrolithotomy using fluoroscopy guidance for the puncture and the dilation. Over the last several years, we’ve transitioned almost entirely to ultrasound use. Ultrasound is used very widely in other countries that don’t have easy access to fluoro such as parts of Asia and Europe, and there are a lot of good things about it. Nowadays, I use ultrasound for all my access and we’ve published data that, at least in our experience, it’s easy to learn.
Also see: ‘Imaging gap’ seen in post-URS patients
If you have any abdominal ultrasound that you can use in the operating room, the first skill is figuring out how to image the kidney well. After that, it’s learning how to guide the needle into the kidney. One of the reasons it’s easier in my mind is that you can distinguish between posterior and inferior calyces easier.
If providers aren’t used to using ultrasound, having a fluoro as a bail-out is a good idea. We’ll get our needle entry in the calyx of choice and then use any coaxial wire with a J-tip on it. Generally speaking, a coaxial wrapped movable cord wire with a J-tip is my wire of choice, which I put down the needle into the collecting system. When I see that it’s inside, I make the tip floppy so that we don’t injure or perforate the collecting system.
I back out the needle and then use an 8F or 10F dilator to get to the fascia, then switch that out for a safety wire introducer, and put a second safety wire in place. I pin that off at the side and then I usually use a balloon. I think the balloon is nice because it’s a single-set dilator as opposed to serial dilation, and we’ll dilate up. My normal tract now is 24F and so I use a 24F sheath, which requires a 20F or 21F nephroscope, which is a good match for that sheath.
Then you use your lithotrite of choice. My current instrument is the UreTron, made by Med-Sonics, but the Olympus ShockPulse and CyberWand are excellent and Boston Scientific makes a great device. There are a lot of great lithotrites out there. Afterwards, I do tubed nephrostomy. I’ll leave an 8F or 10F nephrostomy tube, usually a Cope, in place. Our patients generally stay 1 or 2 nights in the hospital and most have the nephrostomy tube removed at the point they go home.
The use of ultrasound for PCNL is unique to you and your practice. What is your best tip for using ultrasound?
My best tip is to use ultrasound on everybody, which will get you through that first learning curve-learning how to image the kidney well. When I started out, I put an ultrasound in my office and I performed ultrasound on every patient. When they came in for something unrelated to their kidneys, I would still say, “If you don’t mind, I’ll take a look at your kidneys,” and I would actually turn them prone in the office and ultrasound their kidneys. That let me do more in the operating room.
Then, in the operating room, I would just give myself 5 minutes and do whatever I could. Initially, it was just imaging, and then over time, as I got more done in that 5 minutes, I would try one pass of the needle. If you’re using an 18-gauge needle or a smaller needle for a single pass, if it doesn’t work out it’s not going to hurt anybody. If you stick to that 5-minute rule, you’ll be learning consistently but you’re not going to waste any time and nobody’s getting mad at you for trying something new.
If you had a really tough anatomic case, would you still go with ultrasound or is there a point where you’d go back to fluoroscopy?
The ideal patient to start off with is one who is not super obese and who has moderate hydronephrosis and a pretty simple stone. I think the most challenging ones are where you have a staghorn stone, non-dilated case in a patient with a high body mass index. In our last 100 cases or so, more than 90% of the time I don’t even wear lead, so it’s pure ultrasound guidance head to toe.
The times when I have had to use fluoro to get myself out of trouble are for a really complex anatomy and non-dilated systems with big stones, so I think that having a “plan B” is a good idea. Whether your plan B is having a fluoroscopy machine in the room or having an interventional radiologist or a senior colleague there to help you out, having that plan B is what helps you to transition over.
Next:Getting informed consentHow do you get informed consent for a PCNL? What do you talk about with patients?
I go through the risk of a bowel, lung, or visceral injury in a lot of detail, because even though the risk is relatively low, they’re very impactful for the patient. I always review the risk of bleeding. In our institution, it’s about one in 100, and I will tell patients that if that does happen, usually they’ll need a transfusion but that sometimes they’ll need an embolization or stent placed to deal with the bleeding issues. I always talk about pain. I tell them there will be a fair amount of pain for about 3 days and that they’ll have a nephrostomy tube and a Foley catheter, usually for one night.
What would you tell someone who has a lower volume practice in PCNL? How would you advise them to gain experience and get better?
That can be a real challenge because even at the trainee level, the access is key. The access is everything. You only have a certain number of “at-bats,” even while you’re training, and when you get in a practice and you’re not doing a lot of them, those opportunities come up infrequently.
I’m a big advocate for getting your own access because that’s the key to making the procedure go well, but at the end of the day, patient safety is the most important thing. Whether you’re partnering up with an interventional radiologist or you’re doing it yourself, do whatever you’re most comfortable with to get good access. If you’re going to partner with your interventional radiologist, having a great relationship and being present so that you’re helping them to make a decision on where that access goes are key to making that portion of the procedure go well.
What would you tell someone who is just starting in their practice? Is PCNL something they should try to retain, or is it something more for fellowship-trained urologists?
My experience has been that most of the people who end up leaving our program and then doing PCNL in a practice who are not fellowship-trained are people who left their residency comfortable with the procedure at that point. Patient safety always comes first, so you shouldn’t push yourself to do something you felt uncomfortable with at the time of your training. At the same time, we have had a lot of people come to learn ultrasound from us because part of what makes fluoroscopy tough is that it takes a lot of cases to get it under your belt. Having better instrumentation and having an easier access approach can help you to do it in your own practice. It is a challenging case, it is a humbling case, and the margin of error can be very high. You have to feel confident, particularly with the access portion, to do it well. If you’re not comfortable with getting access, having a good relationship with an interventional radiologist and doing the rest of the procedure yourself is a very reasonable way to go.