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Urology
August 29th, 2019

Ask Dr. Schwartz: Questions and concerns


We sat down with Dr. Bradley Schwartz, Chairman of Urology, Southern Illinois University, to discuss his experience with the Resonance® Metallic Ureteral Stent. In the third installment of this three-part series, Dr. Schwartz addresses a few common questions and concerns he hears about using the Resonance stent.

Refer back to video one to hear Dr. Schwartz talk about his approach to treating extrinsic ureteral compression and video two for a detailed overview for using the Resonance stent in practice.

To schedule a tele-education or Resonance event with Dr. Schwartz, please email: VistaUS-URO@CookMedical.com.


In your experience, how does the Resonance stent affect UTIs?
The Resonance stent really has no effect—either positive or negative—on infectious problems. So, we don’t place them for infection, and by placing them, we don’t induce infection. If a patient has a perceived increased UTI numbers, or incidence, then we probably need to explore their bladder function, maybe how well they’re emptying, maybe they need to be put on different medications to help bladder emptying, etc. UTIs is a very, very interesting topic. And as urologists, we all know that when someone else tells us about a UTI, probably 80% of the time it’s actually not an infection. These patients are having stents, they might have an abnormal urinalysis, but their urine culture is sterile. So, they do not grow anything out. So those are typically not true infections.

We don’t put these stents in to help infections. These stents really have nothing to do with infections. In my opinion, and clearly in my experience, a lot of these stents are going into older patients who already have some element of bladder dysfunction or voiding dysfunction. So, when I have patients who call (or whose primary physician calls, kind of co-managing these patients), and they always have UTIs, they always have symptoms, what we try to do is facilitate bladder emptying. So again, a lot of these patients have dysfunctional voiding. So they either hold on to their urine too long, they don’t empty their bladder well. A lot of the older women have estrogen problems; they have urethral problems. And I actually get my bladder specialist involved to help any kind of lower urinary tract issues. So, I’m going off the topic a little bit, but I think really that a lot of these preconceived notions of “these stents are all causing UTIs and bladder problems”—they’re not any different than any other stent, from a tolerability issue. 

What challenges have you experienced when using the Resonance stent?
So, while saying all the great things about it, as you all know, not all of our products are 100% and universally tolerated and successful. Some of the things that I’ve run into—first of all, when you look at, like we talked about the extrinsic compression before, what we like to do in urology is break it down between benign and malignant ureteral obstruction. You might see these in publications of BUO and MUO. We know from the literature, from virtually every paper that’s ever been published regarding these stents: malignant ureteral obstruction has a higher failure rate. These patients are very, very challenging and, no matter what stent you use, from any country in the world, they’re a challenge. And their stent longevity will be less than the patients who have benign ureteral obstruction. So, those patients already for me are a challenge, and I do counsel them that they might need these stents changed a little bit more often than a year.

The encrustation is always a problem with any indwelling foreign body within the urinary tract. Urine is what we call very lithogenic. It has properties and constituents in it that lead whatever foreign body is in there to encrust or calcify. So, I will tell you that luckily, and fortunately, with the metal stents, we’ve really only had two memorable, really significant complications with encrustation. You would be amazed that when you pull these stents out after a year, they’re discolored. Very important teaching point for the people in the field that when you pull these stents out, a black stent is not bad. That’s just what happens to the metal when it’s been indwelling. But encrustation per se, on these Resonance stents, is really very, very unusual. We do not encounter it very often at all.

One memorable complication that we had was a gentleman had a TURP procedure and the outside urologist resected both ureteral orifices, put bilateral stents in for temporary drainage, and then sent it to us for management. He did not want any other procedure—pretty healthy guy, actually, a pretty normal, healthy, walking, talking guy who’s a really nice guy. And he did not want the definitive re-implant procedure. So, I talked to him, talked to him about the Resonance—we could do it for year—and he was very up for that. We put in metal stents, and he came back with some flank pain. An outside hospital obtained a CT scan. And he had about a 3.5- to 4-centimeter stone on the proximal end of the RMS. And this was after about two months indwelling, which was amazing. Never seen anything like that before or since. We had to percutaneously address his stone. And we still change his stents, but we change them to the silicone stents that Cook has. He’s tolerated them well, and he’s had, interestingly, no encrustation problems. We did have another encrustation complication in the bladder, but again, we had to use a laser to break up the bladder encrustations.

The other complication that we had, that I had to percutaneously correct—and it was clearly surgeon error—was when these curl, and when they coil both in the bladder and in the renal pelvis, you need to have—on x-ray, under fluoroscopy—you need to have a very, very distinct look to the coil. And it has to look really just like this on x-ray. What we did, and I didn’t realize it—it was only in hindsight—but when we put it into the renal pelvis, it was sticking out, very subtle, in a very small amount, it was sticking out like this. And what it was doing, it was actually stuck on the inside of the renal pelvis. And the woman had absolutely no problems, over the year. She had no concerns. But when we went to go take the stent out, it would not come out. And we percutaneously went in and what happened was that the tip of this stent right here started growing into the renal pelvis. So, we actually had to resect the tissue, the ingrowth of the tissue around the stent. We placed another one, antegrade, we put another metal stent in antegrade, and we still changed her stent as well. But we are now ever so cautious to make sure that we have—you really need this look on the x-ray or else you’re going to be subject to a potential ingrowth with that tip on the tissue.

How would you address an issue where the stent didn’t drain well and a physician was unsure about trying the stent again?
No matter how good we think we are, no matter how great we think our tools are, not everything works 100% of the time. So, if I have a failure with something, it’s pretty rare that I just throw it out the window. Whether it be my technique, the device, whatever it is. So, I think if someone has a bad experience with something, maybe they can kind of reassess—what was it? Was it the material? Was it the stent? Was it the disease? Was it the patient? Was it patient factors? Was it something else? And you know what, it’s hard to convince some urologists that one failure doesn’t mean that you completely get rid of that whole technology.

We’ve had failures. We’ve had complications. I have failures and complications with virtually every surgery, every technique, and every device that we use. But it doesn’t necessarily thwart my desire to maybe push the envelope, go to the next step, do something different that’s going to help these patients with the devices that we have available to us. If they experience failure because of ongoing obstruction, ongoing, worsening hydronephrosis, worsening kidney function, etc., then let them look for another patient. They got to have another patient that is a good candidate for a long-term stent that will work. And it’s dealing with personalities and dealing with fairly driven professionals. And sometimes that might be difficult, but I think offering a second chance and trying something again is always worth the extra effort.

How do you address the MRI compatibility of the stent?
We certainly get a lot of questions about CT scatter and about CT imaging and MRI. These are MRI conditional, up to three tesla. That’s what their manufacturer guidelines are. And then on CT scan, we all might be familiar with a lot of scatter and a lot of really distorted effects from hip and knee prostheses and spinal implants and things. The RMS does not have anything like that on CT imaging of the stent. So, for imaging purposes, it actually shows up really, really bright and really nice. So, it’s very distinct. But it doesn’t really have any distortion, and it doesn’t have anything that might obscure your image of the disease or what you’re trying to see.

In closing…
We’ve talked about a lot of the complications, indications, and maybe some of the techniques that we can use to really help our surgeons out and ultimately help our patients. I’m available for intraoperative problems if you need to, and certainly would hope to see you at any RMS event or any other event that we have where we can educate and teach anybody in the use of these products.


Dr. Schwartz is a paid consultant of Cook Medical.