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BackTable / VI / Article
Percutaneous Nephrostomy for a Non-Dilated Collecting System
Lauren Fang • Mar 26, 2021 • 692 hits
Non-distended collecting system nephrostomy tube placement can often be challenging, requiring more advanced techniques. Interventional radiologist Dr. David Field discusses common indications, procedural steps using the Philips XperGuide CT software (and without it), as well as tips for working through challenges and preventing complications.
We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable Brief
• Common indications for non-distended collecting system nephrostomy tube placement: staghorn calculi requiring percutaneous access for stone removal and complete urinary diversion.
• The Philips XperGuide CT helps pick a target calyx and entry point on the skin. The software system creates the exact fluoroscopic angle under which to stick. Stones are easy targets, but if it's a nondilated system for urinary diversion, Dr. Field gives the patient IV contrast with a 10 mg chaser of Lasix, which helps pump up the collecting system for easy visualization. Patients are usually under anesthesia to minimize movement. Often, ultrasound guidance is not necessary for non-distended patients, as CT and fluoroscopy guidance provided by the Philips system is adequate.
• Without the Philips XperGuide CT system, it is still possible to perform a percutaneous nephrostomy for a non-dilated system using ultrasound and direct fluoroscopy. Injecting air can sometimes help if there is obscuration by previous IV contrast attempts.
• Bleeding is the main potential complication with nephrostomy tube placement in a non-distended system. Organ injury is not a common pitfall if detailed ultrasound imaging and planning is done prior to obtaining access. While the tendency is to approach with an inferior to superior angle on the needle, it is important to consider the most direct path possible for the urologist planning a stone removal.
Table of Contents
(1) Indications for Non-Distended Collecting System Neph Tubes
(2) Non-distended Neph Tube Placement with Philips XperGuide CT
(3) Non-Distended Neph Tube Placement without Philips XperGuide CT
(4) Pitfalls and Complications
Indications for Non-Distended Collecting System Neph Tubes
Staghorn calculi requiring percutaneous access for stone removal is a common indication for nephrostomy tube placement. Increasingly more common are patients requiring percutaneous nephrostomy for complete urinary diversion.
[Aaron Fritts]
First of all, tell us some common scenarios where a non-distended collecting system needs a neph tube.
[David Field]
Sure. The patients that we do the most on are patients who have staghorn calculi who are needing percutaneous access for stone removal by urology, but also quite commonly, and probably increasingly commonly, are patients who need complete urinary diversion. These are patients who have had Fournier gangrene and have leakage from a, sort of, a damaged urethra; patients who have a pelvic malignancy and who have a physical vaginal fistula that just will never heal because they're just going to keep leaking urine through it; patients who have had pelvic radiation because of a tumor and have radiation cystitis and have just continuing hematuria. All of these patients need urinary diversion and often we will get asked to do that. It's really almost never an emergency, it's just these are chronic problems that just need to be fixed.
[Aaron Fritts]
Right, so it's usually preoperative or perioperative having maybe something to do with, or related to, a tumor, I guess.
[David Field]
Yeah, or just patients whose quality of life is such that their perineum is continually bathed in urine and it's just skin breakdown, or they have such bad bleeding from their bladder. Some of the patients have bladder tumors, so the urokinase and then urine it just makes them continually bleed, and it's never bleeding enough that they are unstable, but these patients need continual transfusion just to maintain their blood loss. If you can remove the urine bathing the tumor, that often will help it stop. Of course, these patients have completely nondilated systems, and that makes it very hard to get into.
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Non-distended Neph Tube Placement with Philips XperGuide CT
Dr. Field uses the Philips XperGuide CT to help pick a target calyx and entry point on the skin. The software system creates the exact fluoroscopic angle under which to stick. The C-arm goes to a specific position and the needle is advanced straight down along the beam. About halfway through, the machine will rotate to the other 90-degree angle and the needle can be advanced to the target. Stones are easy targets, but if it's a nondilated system for urinary diversion, Dr. Field gives the patient IV contrast with a 10 mg chaser of Lasix, which helps pump up the collecting system for easy visualization. Patients are often under anesthesia to minimize movement. Ultrasound can be performed ahead of time to obtain more information about where the kidney is related to other structures or to get an idea of a general area to be prepped, but often the CT and fluoroscopy guidance provided by the Philips system is enough.
[Aaron Fritts]
How do you approach these guys?
[David Field]
The way to get in them more easily is to make them a: easier to see, and b: bigger. We have a Philips system that has a guidance software package attached to it, their XperGuide CT. We basically can do an on-table DynaCT and then the cone beam CT image that is generated allows you to pick a target calyx and the entry point on the skin, and you thereby know that there's nothing in between the skin and the calyx. It will create the exact fluoroscopic angle under which to stick the system. Once you've selected your target, and your skin entry, the C-arm goes to a specific position and then on the fluoro screen, there is a target where you start your needle and then under fluoro, you just advance it straight down along the beam. About halfway through, the machine will rotate to the other 90-degree angle and then you can follow your needle to the target.
[Aaron Fritts]
Are you trying to stick right down to the stone? Is that what you're trying to do?
[David Field]
Right, well we pick the target. If it's a stone, then it's an easy target, right, but if it's a nondilated system for urinary diversion, I will give the patient IV contrast and I usually give them about 90 milliliters, if it's unilateral. If it's bilateral, I will usually give about 75 on one side and then have to give some more on the second side, but if you give the patient the IV contrast with a 10 milligram chaser of Lasix, the system will pump up right under your eyes. As long as the patient is ready to go, then you can give the IV contrast, give the Lasix, and then you do your DynaCT and you will see the calyx light up and pump up because with the Lasix you actually have a much better target.
[Aaron Fritts]
Give the Lasix, and then how long do you wait usually before you do your cone beam CT?
[David Field]
I usually wait about five minutes. But during that five minutes, intermittently fluoro, and if you start to see the calyx appear under fluoro then you go ahead and do it.
[Aaron Fritts]
Then you work on like a timer? Are you pressed for time after that?
[David Field]
No, not in that instance because once you've done the DynaCT, you have your target. You can define your target based on the image you get from that fluoroscopic CT, and even if the contrast empties out of the calyx later, you can still use it as a target because you're just asking the computer to define that target for you.
[Aaron Fritts]
I see, and if the patient moves, does that matter?
[David Field]
Well yeah, if the patient moves, it's a hassle. We will often do these with anesthesia. The patient's prone, so they always like to tube the patient, so they can do apnea, they can do breath holds. That actually makes it much easier, so we do the breath hold right before the DynaCT. They're motionless. Then as you move the needle, you also ask the anesthesiologist for apnea and that makes it much, much easier.
[Aaron Fritts]
Are you using ultrasound at all in those cases?
[David Field]
In those cases, often not.
[Aaron Fritts]
It's just pure CT and fluoro?
[David Field]
Exactly. I will often ultrasound ahead of time just to get more information about where the kidney is related to anything, or to get an idea of a general area to be prepped, but often just the fluoroscopic guidance that is provided by that Philips system.
[Aaron Fritts]
Ideal for just basically helping to direct your needle exactly where it needs to go without any guess work basically is what it sounds like.
[David Field]
Exactly. There's no guesswork. You know where you're going to end up, you know where you're going to start, and you know that there's nothing in the way. If you think that there's pleura in the way, you can just bring your skin entry point more inferiorly. The tricky part is just following the dotted line, basically, that the software produces under fluoro. You still use an INRAD needle just because that's what we use, but we drive with a hemostat under fluoro, and that's really the only difficult part is staying along the path that the software has determined.
Non-Distended Neph Tube Placement without Philips XperGuide CT
Dr. Field explains how to perform percutaneous nephrostomy for a non-distended system without fancy imaging software like the Philips XperGuide CT system using ultrasound and direct fluoroscopy. The right amount of IV contrast helps opacify the system while the Lasix helps to pump it up. Injecting air can sometimes help if there is obscuration by previous IV contrast attempts.
[David Field]
A lot of people don't have this capability, so we should probably talk about how you can do nondilated systems if you don't have the magic of the software that will tell you how to guide your needle. What I did before we got this system was ultrasound the patient first, and plan a path into the kidney just under ultrasound making sure there's nothing in the way, making sure that I'm hitting the right part of the kidney, and then I will mark on the skin where I'm planning to stick. Then I would actually put the C-arm in position so that I can stick down that path, so you tilt a little caudad, a little LAO if you're doing a left-sided stick. At that point, with everything ready to go, like the 21-gauge needle in hand, that's when I give the contrast and the Lasix. You do have a very short, or a relatively short, window of time during which you're able to stick because you do it directly under fluoro, so you just intermittent fluoro until you see the calyx appear, it will get a little darker, a little bigger, and then you have to stick definitively. It's really just the same thing. I will fine tune the patch by basically putting like a hemostat at the point I know I'm going to start at on the skin, and then moving the II so that directly overlies the dilated and newly apparent, and opacified calyx. Then I just stick straight down the beam, parallel to the beam, into that calyx. You're looking right down the needle. I will always take a still shot as well because then you get a much better picture of what you're sticking, but then actually stick under fluoro. Then, once you think you have made it there, then you have to bring the II to the lateral position and you can tell whether you are through and through potentially, or you're not quite there yet, but you'll be very close.
[Aaron Fritts]
Right, then you have to use your triangulation.
[David Field]
Exactly. Exactly, you're basically doing what the fancy Philip's software does for you. You can do it yourself. In that case, you do have to move relatively quickly because the contrast will empty out of the collecting system.
[Aaron Fritts]
Have you ever had to re-inject?
[David Field]
No, but certainly have not been in when the contrast has gone away and, in that case, you know you're close, you know your needle is close and then you just have to figure out exactly where you are and then kind of restick and inject a little bit of contrast, again, not injecting too much not to obscure your path. It's definitely more challenging than have the software do it for you. As long as you have fluoro and the trick really is the IV contrast to opacify the system, and the Lasix to pump it up. I'll give 10 milligrams usually per side.
[Aaron Fritts]
Okay. In terms of the next step, once you get that needle where it needs to go, do you ever inject air?
[David Field]
Sometimes, especially if there's obscuration by previous attempts, that certainly helps. It also helps if you are not quite sure where you are and it looks like you maybe are not in. Air, obviously, is non-dependent, whereas contrast is heavier. The patient is prone, so if you inject contrast it's going to preferentially fill anterior calyces as opposed to posterior calyces. Of course, you want to be in a posterior calyx, so air is certainly good for that.
Pitfalls and Complications
Bleeding is the main potential complication with nephrostomy tube placement in a non-dilated system. Dr. Field has not encountered issues with injuring the colon, kidney, or the pleura, as he reviews all imaging in detail prior to obtaining access. Creating the most direct path possible from the skin to the kidney is important when performing a percutaneous nephrostomy for a urologist planning to do stone removal.
[Aaron Fritts]
Any other complications to worry about?
[David Field]
Other than bleeding and sepsis, nothing. These people are not typically infected, right, because they're non-dilated. We really just worry about bleeding.
[Aaron Fritts]
Any other pitfalls to deal with? Obviously, you want to keep an eye on your angle, be aware of the pathway the tube needs to make. Even though it might be the shortest pathway, the angle might not be right. Can you speak to that a little bit?
[David Field]
Right. Well, I think that's mostly important when you're doing access for a urologist who wants to do stone removal either the next day or the same day because they like to come in a really direct path from the skin to the kidney, whereas if you're doing something under ultrasound, your tendency is to have a little bit of an inferior to superior angle on your needle. When you're doing it for a urologist, you want to think about how they want to be looking at the kidney when they do the stone removal and try to come in through a path that is as direct as possible.
[Aaron Fritts]
Gotcha. That makes sense. We already talked a little bit about bleeding and we talked a little bit about avoiding crossing the pleura, what happens if you do cross the pleura? Have you had that happen, and what do you do in that case?
[David Field]
I personally have not. I have not had that happen. I think it's really important to be cognizant of where it is. If you're below the tenth rib, you should be fine.
[Aaron Fritts]
Ever seen a situation where there's been injury? We talked about trying to avoid the colon, but injury to any other organs?
[David Field]
Yeah, I've not. I've not seen that personally, and I think that really is one of the main points of safety when you're doing a nephrostomy of any sort is being very cognitive of where the colon is and where other things are, and under an ultrasound, it can be a little bit hard to see a colon that is potentially decompressed in that area. Looking at the pre-procedural imaging is very important and also just being cognizant of what is between the skin and the kidney.
[Aaron Fritts]
Right, and with that, a lot of times morbidly obese patients it's almost impossible to use ultrasound or it's extremely limited. In those cases, even for the distended kidney, do you guys find yourselves using DynaCT more often?
[David Field]
Occasionally, but it's really mostly for the non distended because it involves anesthesia and it involves just a little more of a hassle.
Podcast Contributors
Dr. David Field
Dr. David Field is a practicing Interventional Radiologist at MedStar Georgetown University Hospital in Washington DC.
Dr. Aaron Fritts
Dr. Aaron Fritts is a Co-Founder of BackTable and a practicing interventional radiologist in Dallas, Texas.
Cite This Podcast
BackTable, LLC (Producer). (2020, November 30). Ep. 97 – Nephrostomy Tube Placement: Basic to Advanced [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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