In this interview, Brian R. Matlaga, MD, MPH, discusses factors to consider in the decision to utilize ureteroscopy versus shock wave lithotripsy, how to counsel patients on the optimal approach, how to minimize the morbidity of each modality, and why younger urologists are more likely to perform ureteroscopy.
How you decide between ureteroscopy and shock wave lithotripsy?
The decision making is often very challenging because so much of what we try to do now in urology is leverage our understanding of clinical evidence to guide and counsel our patients. With shock wave lithotripsy and ureteroscopy, it’s a complex discussion because the evidence can be conflicting or unresolved in certain scenarios, and there may not be explicit guidelines to advise us. So it’s a decision that you really have to involve the patient with in order to understand their expectations of the outcome and to discuss with them the relative advantages and disadvantages of each approach.
The nature of the two procedures is very different. Shock wave lithotripsy is typically a completely noninvasive modality that may have success rates that are a little lower than ureteroscopy. Ureteroscopy is little more invasive, but for certain stones success rates may be higher than that of shock wave lithotripsy.
Sometimes, patient bias will drive the decision. Does the patient want to maximize the chance of a successful outcome in a single procedure? Would they rather have a noninvasive procedure? It’s about helping to educate the patients so they can understand what their own desires are as far as the outcome they would most prefer.
Do you think that the long-term risks of shock wave lithotripsy, such as hypertension and diabetes, are overstated?
It’s very common now for patients who have been diagnosed with a stone to look up treatment options on the Internet and find reports about hypertension and diabetes being associated with lithotripsy.
I think hypertension and diabetes are two completely separate issues. In my opinion, the evidence may be slightly more compelling for the association of hypertension with shock wave lithotripsy. Although the literature is certainly not definitive, there may be a modest effect of shock wave lithotripsy on blood pressure, although it may not be clinically meaningful. The diabetes association was more sensationalized in the lay press, but I think the evidence is far less compelling than that for hypertension.
I counsel patients that our understanding of the literature is that there may be an association between lithotripsy and hypertension, and it is likely a dose-dependent relationship. If you have a single session of shock wave lithotripsy, it’s unlikely to have an effect on blood pressure, but if you have many, many sessions over a long period of time, you may see an effect, but it may not have any clinical meaning. With diabetes, the literature is far less well characterized. At this point, I don’t think that there is any good evidence that shock wave lithotripsy causes diabetes, so I feel comfortable reassuring patients about that.
What are some strategies to decrease the morbidity of shock wave lithotripsy?
Shock wave lithotripsy, unlike some of the other surgical approaches we have as urologists, is more of a “black box.” Compared to other things we do in the operating room, such as endoscopic, laparoscopic, or open procedures, shock wave lithotripsy does not give us definitive, real-time feedback as to how the procedure is progressing. All urologists know, I think, that the fluoroscopic appearance of a stone during lithotripsy may not truly indicate the procedure’s ultimate outcome. However, we can control patient selection; that is, optimizing who we’re going to treat with shock wave lithotripsy. That is probably the first step to controlling the morbidity of the procedure.
During the treatment, there are only a few parameters we can control. We can control the power settings of the lithotripter. Animal models have demonstrated that slowly ramping up treatment power during the initiation of shock wave lithotripsy can reduce injury to the kidney.
Urologists can also ensure that the patient is well coupled to the machine—the process by which the patient is joined to the lithotripter—which with modern dry-head lithotripters typically involves the use of a coupling medium such as a gel to maximize energy transfer into the patient. When the patient is properly coupled to the lithotripter, you maximize the amount of energy that’s deposited in the stone, so you can minimize the number of treatment sessions and number of shock waves to which patients are exposed.
We can control the rate at which we deliver shock waves. From a clinical standpoint, a slower rate—in the neighborhood of 1 Hz or 60 shocks per minute—is associated with better clinical outcome. There is also evidence in animal models that this is associated with less injury to the kidney.
The other element we can control is the anesthetic technique we employ. There are reports that patients who are treated with a general anesthetic have better outcomes than patients who are treated with intravenous sedation.
Let’s shift gears to ureteroscopy. More young urologists perform ureteroscopy; does this make sense to you?
I think so. We’re in an endoscopic epoch of urology. In training programs now, urologists are being exposed to endoscopic surgical approaches much earlier than they were years ago. Flexible ureteroscopy has gone from being commonly performed at the chief resident level to being commonly performed at the junior resident level. The residents have much more robust experience with endoscopic surgery in the course of their training program, at least in the United States, such that as they finish, they oftentimes have performed many more ureteroscopic stone cases than they have shock wave lithotripsy procedures.
As a result, they have already passed that learning curve and they’re very facile with the required surgical techniques. It’s a true trend, and it makes sense, given how our training programs have evolved with regard to endoscopic surgery.
Do ureteroscopy patients always need a stent?
That’s a very good question because more often than not, patients who undergo ureteroscopy have a stent placed in the course of that procedure. This is despite the fact that there are a number of studies suggesting that for uncomplicated ureteroscopy, patients don’t need stents and their outcomes are no different than patients who have stents. Further, patients with stents tend to be more uncomfortable.
In my practice, we utilize ureteral stents following ureteroscopy fairly routinely. One of my mentors used to say that he never had to come into the hospital in the middle of the night to take out a stent—all it takes is one or two unplanned stent replacements to affect your practice patterns. In my experience, we use stents in the vast majority of cases.
What are the best technical advances in ureteroscopy of late?
From an endoscopic approach, the fiberoptic scopes we are using nowadays are very miniaturized. They are very deflectable and allow you to access all parts of the kidney: the lower pole, the upper pole, through tight stenotic infundibula into remote calyces of the kidney. The fiberoptic scopes are very durable and have a great ability to facilitate our navigation through the kidney.
Digital ureteroscopes aren’t quite the workhorse, everyday type of scope yet, but they’re likely where our endoscopic technology will be moving. As anyone who has used them will say, they produce amazingly beautiful pictures of the kidney. The detail you can see is far above what is seen with the fiberoptic scopes. I think we’re in the process of moving toward digital technology.
The other advance we have seen is tremendous miniaturization of the implements we use. For example, through the flexible ureteroscope, anything you need to do can be done with a device that’s less than 2F in diameter. Not only are they small, but they are very durable. You can use a basket that’s 1.5F or 1.9F in size, and it will last throughout the entire case. They’re much more durable than they had been in the past.
We also have devices that can help get you out of difficult situations. For example, they allow you to more easily release stones when you grab them to minimize the chance of having an entrapped basket in the ureter, which is very anxiety provoking for a urologist. Other devices allow you to pass a laser fiber alongside the basket to fragment a stone if it is stuck in a basket.
What’s the largest stone you would treat with ureteroscopy?
I don’t know that there is a hard and fast cutoff, because so much depends not just on the stone but also on patient-specific factors. In an otherwise healthy patient without significant comorbidities, once you get a stone size in the neighborhood of 1.5 cm or so, that’s where you’re going to see ureteroscopy becoming technically challenging. You’re dealing with a large volume of stone and as the stone fragments, you’re dealing with a large volume of debris within the kidney. As a result, visualization may become problematic, and you are left with a lot of stone material that may have to be extracted at the end of the procedure. With a 1.5-cm stone, especially for a urologist for whom flexible ureteroscopy isn’t a common part of their practice, the patient may require a multiple-stage approach.
When you get above 2 cm, you are very likely to require a staged treatment approach to ureteroscopy. It’s important to make sure the patient understands that this is going to be a process rather than a single procedure.
In terms of patient-specific factors, sometimes a patient is just unfit for percutaneous surgery. For example, they may take an anticoagulation medicine that they can’t safely stop due to medical comorbidity. In that patient, you may have to treat a larger stone ureteroscopically because shock wave lithotripsy is not an attractive option due to risk of hematoma, and percutaneous surgery is not an attractive option due to the risk of bleeding. There will be some outliers, but if you look at the average patient, once you are in the neighborhood of 1.5 to 2 cm, that’s going to be a more technically complex procedure.
Are the numbers the same for shock wave lithotripsy?
I think so. The only caveat is that with ureteroscopy, we utilize stents routinely. The great putative benefit with shock wave lithotripsy is that it’s a noninvasive technology, but when you get into the larger stone size, there’s an increased likelihood of the kidney having a difficult time discharging all the stone fragments. That can lead to steinstrasse, which can be problematic for the patient postoperatively. The upper limit of ureteroscopy is probably also the upper limit of shock wave lithotripsy, and that’s the size range where ureteral stents may be involved in that treatment.
If you had an 8-mm ureteral stone, which treatment would you want?
For stones in the ureter, we have a good understanding of the clinical evidence, which indicates that ureteroscopy tends to be associated with slightly improved stone-free outcome compared with shock wave lithotripsy. For shock wave lithotripsy, the efficacy in the ureter is not quite as robust as it is in the kidney. Treating a ureteral stone ureteroscopically is more straightforward than it was 5 to 10 years ago now that we have improved visualization with scopes, miniaturized laser fibers, and baskets. So my bias for ureteral stones in myself or for others is toward ureteroscopy.
What do you think the future holds?
I think the future in stones is really exciting. The question that comes up at scientific meetings is, is there is a role for shock wave lithotripsy in the future and can stones be treated entirely endoscopically? I think there’s a place for both technologies, and I think that what urologists are trying to do now is better understand who is going to be best treated with shock wave lithotripsy and who is going to be best treated with ureteroscopy. The magnitude of the innovations we’ve seen with the endoscopic approach in the past decade has been very exciting to those of us who treat stones commonly, because we are able to do things now much more easily, much more safely, and much more rapidly than we could previously.
I think that’s why we have seen this tremendous interest at the training level in ureteroscopic approaches. In practice, we are seeing more ureteroscopy being performed now than we have in the past. That trend may continue, but I think that the future is probably going to be in better predicting treatment outcomes, including through imaging approaches, and then better counseling of our patients.
We will be able to better inform them that for certain stones, they can expect certain outcomes, and we will know who is going to be best treated with ureteroscopy and who is going to be best treated with shock wave lithotripsy.UT
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