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BackTable / OBGYN / Article
Kidney Stones During Pregnancy: Surgical Intervention
Melissa Malena • Jun 7, 2024 • 37 hits
The management of kidney stones during pregnancy comes with unique challenges as many surgical stone removal modalities are contraindicated with pregnancy. Despite these contraindications, pregnant patients may still require surgical intervention, especially in cases necessitating urgent decompression. Drs. Suzette Sutherland and Dr. Alana Desai of Washington University share their expertise on kidney stone management in pregnant patients.
This article features excerpts from the BackTable OBGYN Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable OBGYN Brief
• Urgent decompression can be accomplished in pregnant patients through either a ureteral stent or percutaneous nephrostomy tube, depending on local capabilities and patient needs.
• Roughly 70% of pregnant patients can successfully pass kidney stones with expectant and pain management, while 30% require surgical intervention.
• Ureteroscopy is the surgical intervention of choice in the pregnant patient, guided by ultrasound and small levels of fluoroscopy.
• Percutaneous nephrolithotomy (PCNL) and extracorporeal shock wave lithotripsy (ESWL) are contraindicated kidney stone removal modalities for pregnant patients.
Table of Contents
(1) Urgent Decompression: Ureteral Stent vs. Percutaneous Nephrostomy Tube
(2) First-Line Surgical Management: Ureteroscopy
(3) PCNL & ESWL are Contraindicated During Pregnancy
Urgent Decompression: Ureteral Stent vs. Percutaneous Nephrostomy Tube
In cases necessitating emergent decompression, deciding between the use of a ureteral stent or a percutaneous nephrostomy tube should be dependent on local capabilities and available options for later definitive treatment. Although radiation exposure is an important concern in pregnant patients, communication with interventional radiologists is imperative to determine the best treatment modality as later complications can result in increased radiation exposure.
The general consensus skews towards the placement of percutaneous nephrostomy tubes in pregnant patients, which avoid the combined pressure of a stent and growing fetus on the bladder, but Dr. Desai recommends a patient-specific decision-making approach as a percutaneous nephrostomy tube is not always advantageous. Once the decompression tool has been installed, the stents should be changed every four to six weeks until delivery; after which, further decompression management can then be discussed.
[Dr. Suzette Sutherland]
The other big thing that's often debated right at our academic meetings and at the podiums, whether if a woman needs urgent decompression, should it be with a ureteral stent or a percutaneous nephrostomy tube, especially if she has to have it in there for the rest of her pregnancy. What are your thoughts on that and what's the data show?
[Dr. Alana Desai]
Sure. As always, institution dependent, what resources are available, whether there's interventional radiology even available, they can either go to an immediate nephrostomy tube or ureteral stent placement. Again, the decision is based on local capabilities with definitive treatment at a later date. Both modes of decompression are associated with rapid stent or tube incrustation. Both tubes have to be changed every four to six weeks. Early in my training, so 20 years ago, everyone was managed with just decompression with frequent changes every four to six weeks.
[Dr. Suzette Sutherland]
Have the ureteral stent or the PERC tube or both?
[Dr. Alana Desai]
Correct, both. A recent paper by Lyon and colleagues led by Smita Day showed that nephrostomy, actually it's in PREST, initial nephrostomy tube placement is associated with a higher number of procedures and radiation exposure per procedure and total radiation exposure per suspected stone episode compared with stent and ureteroscopy, with definitive ureteroscopy being the optimal mode of intervention when possible. Interestingly, in their paper, they did not realize that they said this several times that their interventional radiologists were not using ultrasound guidance to place their nephrostomy tube.
It is important to communicate with your interventional radiologist what modality of imaging is used. You may think, oh, we're sparing our patients this radiation exposure, but they're ultimately using fluoroscopy. A lot of times when those stents are encrusted or those tubes are encrusted, they're having to get completely different access in exposing pregnant patient and their fetus to higher levels of radiation than we even expected. Again, that communication is really important.
[Dr. Suzette Sutherland]
I think many people have thought that nephrostomy tubes in a pregnant patient might be easier for them to manage if you don't have the stent going down to the bladder, causing these bladder symptoms besides the baby pushing on the bladder. There's been a lot of advocacy in that direction for a percutaneous nephrostomy tube, but you're bringing to light many other things that might make a percutaneous nephrostomy tube not advantageous, of course. I guess it is a little bit of this and a little of that, either way. Correct. Do you think it just really comes down more to patient preference, educating them about the two options? Because clearly they still need to be changed with about the same frequency.
[Dr. Alana Desai]
Exactly. Certain patients do tolerate a percutaneous nephrostomy tube better than a stent and vice versa. I've managed kidney stones for the past 15 years. I've had my handful of pregnant patients with stones. I do recall the ones that were managed early on in my career with nephrostomy tube persistent, and I do recall several percutaneous nephrostomy tube patients coming in every 6 to 10 days for some sort of dislodgement or incrustation or obstruction and I remember my residency to decide this is the longest pregnancy ever, and it's sad as we're not managing this.
We don't see that they're coming back. Our interventional radiology colleagues don't always call us. They certainly can't intervene without our guidance and it happens more often than you think. We only see the majority of stent complications but they can occur just as equally if not more with nephrostomy tube, so it is based on patient preference in local capabilities.
…
[Dr. Suzette Sutherland]
Yes. Well, I think, historically, the thought has been decompress the collecting system, either a percutaneous nephrostomy tube or a ureteral stent and then wait until after the delivery. Do nothing else except for changing your stents every four or six weeks or so, but don't do anything else. I think we know today that that whole philosophy is changing, so beating this question over the head with which one we should be doing is almost an old question at this point.
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First-Line Surgical Management: Ureteroscopy
The first-line treatment for pregnant patients with renal colic from an obstructing stone is expectant management and pain management; 70% of patients will successfully pass the stone without further intervention. For those requiring surgical intervention, Dr. Desai emphasizes the importance of patient-informed decision-making and multi-disciplinary collaboration within OB, anesthesiology, and radiology. Ureteroscopy is the most common surgical interventional technique, guided primarily by ultrasound and secondly by small amounts of fluoroscopy. However, hydronephrosis from pregnancy can make ureteroscopy visualization easier, which allows experienced surgeons to avoid fluoroscopy.
[Dr. Suzette Sutherland]
Why don't we just jump into this idea about just taking care of the stone when you see it, whether the woman is pregnant or not?
We know that there have been a lot of studies now looking at ureteroscopy and safe ureteroscopy and just relieving her of her problem, leaving maybe a temporary stent afterwards but then being done with it. Why don't you talk to us about what your experiences are with that and what the literature would tell us to do today?
[Dr. Alana Desai]
Taking a step back, it is important to note that the vast majority of patients presenting with renal colic due to obstructing stone in pregnancy do pass their stone. The first line is going to be expected management trying to get that pain under control unless they are septic and needing urgent decompression for the reasons we discussed. We should try to get them their pain managed and their stone to pass. Only about 30% of patients will typically go out to need surgical intervention and so, ultimately, consideration of that mode of intervention requires just shared decision-making with the patient and multi-disciplinary collaboration with your team including your obstetricians and anesthesiologists but, again, the vast majority are going to pass.
Nowadays, as you said, ureteroscopy is the surgical intervention of choice because, as we discuss, every single time you're having to change those stents, you're exposing the patient fetus to anesthetic and potentially fluoroscopy. Again, nowadays, ureteroscopy is the intervention of choice when patients can tolerate it, when it's a safe time for them to undergo that procedure. It's important to avoid that during the first trimester if possible but, if needed, they can undergo a short procedure.
[Dr. Suzette Sutherland]
Do you try to do that under ultrasound guidance? Is that possible or just use a little fluoro, or how do you do it?
[Dr. Alana Desai]
You can use a minimal amount of fluoro if needed. I've, historically, in my practice have used just ultrasound. You'd be surprised that hydronephrosis of pregnancy really makes ureteroscopy be a little bit simpler actually. You can have an ultrasonographer or sometimes I've had the radiologist come down and run the ultrasound. Sometimes a tech will come down. Sometimes one of our residents can hold the ultrasound probe over the kidney. You really just need to see that the guide wire into the kidney and the rest you can do provided you're experienced with ureteroscopy and pregnancy, you can do everything under direct vision.
You see that proximal guide wire in the kidney and you can proceed as you would under direct vision and that dilated ureter does make it a little bit easier to navigate and at the case end, you can clearly see the proximal end of the stent and you can place the distal end under direct vision. Again, this does depend on your local capabilities whether you do have an ultrasound available, a tech available, someone else to help you with that ultrasound while you're doing your ureteroscopy.
PCNL & ESWL are Contraindicated During Pregnancy
Percutaneous nephrolithotomy (PCNL) procedures have been performed less than twenty times on pregnant patients. PCNL is not the standard of practice due to the potential risk to the fetus from positioning, anesthesia, and fluoroscopy. Extracorporeal shock wave lithotripsy (ESWL) is another common stone removal modality that is contraindicated during pregnancy. Although some studies show that ESWL performed later in pregnancy does not negatively impact the fetus, ESWL remains contraindicated due to the associated loud pounding which risks fetal well-being. Ureteroscopy remains the primary technique for kidney stone removal during pregnancy. The focus should remain on expeditious stone removal to ensure optimal patient and fetal outcomes.
[Dr. Suzette Sutherland]
Is there ever any indication for PCNL during pregnancy?
[Dr. Alana Desai]
Well, there have been some case reports less than 20 in world literature actually. It's not a standard of practice just because of positioning anesthesia fluoroscopy use. I was actually surprised by the small number of people who have undergone PCNL during pregnancy. Typically, this is delayed till after surgery. Again, like I said, I was surprised by the small number.
…
[Dr. Suzette Sutherland]
The other modality that was still done today and used to be done much more frequently is Extracorporeal Shock Wave Lithotripsy, ESWL, and my understanding is that still it's contraindicated during pregnancy for a variety of reasons that are problematic for the fetus for that loud pounding and so on and so forth. Is that still the case?
[Dr. Alana Desai]
That is still the case. There are studies showing that as well performed inadvertently later in pregnancy did not have any untoward effect. It is still contraindicated knowingly.
[Dr. Suzette Sutherland]
Then back to ureteroscopy. Of course, are there any considerations when you're dealing with a pregnant patient that you need to do besides the use of ultrasound that we talked about? If you can do ultrasound rather than a little bit of fluoro, if you're able to do that, of course, most of it's under direct visualization as you mentioned, but sometimes we lose the stone and you want a little bit of use fluoro. If in this situation, ultrasound to try and say, where did it go? Where can I guide me? Are there other considerations, especially in later term pregnancy with the big fetus in the middle? Does that make it more difficult to maneuver with the ureteroscope or anything they need to consider or just try to do it as expediently as possible?
[Dr. Alana Desai]
I think trying to do it as expediently as possible, minimizing for us the time is needed. It's important again, just to clear the ureteral component. There's probably cases where there are renal stones. Those I think can be saved for a later date. Treating the offending stone, making a procedure expeditious, getting in out safely, I think is key. I have not noticed differences in navigating the ureteroscope in any different trimesters in doing these cases.
Podcast Contributors
Dr. Alana Desai
Dr. Alana Desai is an associate professor with UW Medicine in St. Louis, Missouri.
Dr. Suzette Sutherland
Dr. Suzette Sutherland is the director of female urology with UW Medicine in Seattle, Washington.
Cite This Podcast
BackTable, LLC (Producer). (2024, January 10). Ep. 43 – Urolithiasis in Pregnancy: Balancing Risks & Management [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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