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BackTable / OBGYN / Podcast / Transcript #43
Podcast Transcript: Urolithiasis in Pregnancy: Balancing Risks & Management
with Dr. Alana Desai
In this episode, Dr. Suzette Sutherland and Dr. Alana Desai from the University of Washington discuss the management of urinary tract stones in pregnant patients, considerations for ureteroscopy, and consequences of radiation exposure in the fetus. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) The Incidence of Kidney Stones in Pregnancy
(2) Differentiating Between Kidney Stones & Hydronephrosis
(3) Stone Visualization & Imaging Modalities
(4) Expectant Management of Kidney Stones During Pregnancy
(5) Surgical Interventions: Ureteral Stent vs. Percutaneous Nephrostomy Tube
(6) Utilizing Ureteroscopy During Pregnancy
(7) Indications of Percutaneous Nephrolithotomy (PNCL) in Pregnant Patients
(8) Preventing Kidney Stones During Pregnancy
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[Dr. Suzette Sutherland]
I'm your host again today, Dr. Suzette Sutherland from the University of Washington, and I'm excited to have Dr. Alana Desai as my guest for this special episode talking about the management of urinary tract stones but in the pregnant patient. Good morning, Dr. Desai.
[Dr. Alana Desai]
Good morning, Dr. Sutherland. Thank you so much for the invitation.
[Dr. Suzette Sutherland]
Yes, we're very excited to have you here. Dr. Alana Desai currently is a Clinical Associate Professor at the University of Washington in Seattle, where I now get to call her one of my colleagues. She specializes in endourology and kidney stones. Prior to coming to the University of Washington, she was at Washington University, which is in St. Louis, Missouri. She was there for many years, and we're very excited to have her with us now at the other Washington in Seattle. Again, thanks for being part of this program with us today.
As urologists, Dr. Desai, we generally dread the pregnant patient. Let's be honest, right?
[Dr. Alana Desai]
That's true.
(1) The Incidence of Kidney Stones in Pregnancy
[Dr. Suzette Sutherland]
There's just so many worrisome details to consider, not only the urological details that we consider in the non-pregnant patient, but now we're worried about not only mom, but the fetus. Let's just start to dive into some basics about kidney stones and pregnancy. What's the real incidence of kidney stones during pregnancy? Is the incidence really higher? If so, what are the factors that increase that incidence?
[Dr. Alana Desai]
Sure. Previously thought to not be a higher risk in pregnant patients than the general population, because of the difficulties associated with managing them. The incidence may seem higher, but typically it's not higher than the general population. In a 2020 claims-based analysis of 1.4 million pregnancies, stone disease was found to be diagnosed in only 1% of all pregnancies.
There is some newer evidence from an observational study at Mayo Clinic in 2021, however, that pregnancy does increase the risk of a first-time symptomatic stone, with that risk peaking close to delivery. It does improve about a year after delivery, but there's still a bit higher risk compared to age-match controls going forward. It is also the most common non-obstructive because for hospital admissions, complicating 1 in 200 to 1 in 2,000 pregnancies.
[Dr. Suzette Sutherland]
That's a lot lower than I think most people think about. Certainly you don't see it all the time, but I guess maybe it just makes such an impression on us as urologists when we do see it in the pregnant patient that we think of it. Historically, people have thought that the incidence, maybe, or your chance of having a kidney stone as a woman is higher when you're pregnant because of maybe some hormonal changes or dilation of the ureters. Is any of that then true?
[Dr. Alana Desai]
There are both anatomical and physiological changes that occur during pregnancy due to the enlarging uterus. You can get just hydronephrosis, which typically occurs in about 90% of people by the third trimester, but it can also occur as early as a sixth week. That's just due to increased hormone production, namely progesterone. Because of this dilation, there's also an increased risk of stone migration and obstruction. Stones are twice as likely to be located in the ureter when diagnosed during pregnancy, just because of that migration.
Even when not caused by stones, hydronephrosis in pregnancy can also lead to symptoms. The dilation from the stasis of the urine along with the elevated progesterone causing further ureter dilation and reducing ureteral peristalsis, both of these can promote the formation of stone crystals or urinary crystals. This is further accelerated by the increased GFR, plasma, and the plasma flow rate. These do lead to an increased lithogenic factors, including urinary calcium oxalate and uric acid. The hypercalceria or higher calcium in the urine is also exacerbated by placental production of vitamin D to meet the demands of the fetus.
However, even though these lithogenic factors are increased by this increased flow, there is also an increased excretion of stone inhibitors such as glycoprotein, nephrocalcine, and tamhorsol that should compensate for the lithogenic factors. Again, a stone formation is not necessarily increased in pregnant patients because it is balanced by the stone inhibitors. Again, like you said, it potentially just feels like it's an increased risk in pregnant patients.
[Dr. Suzette Sutherland]
Is it maybe fair to say the incidence of developing a stone isn't necessarily higher in the non-pregnant female, but you described some other factors that might make them move during pregnancy are more likely that they try to start to pass. They may become more problematic during the pregnancy, whereas they were just nice and quiet up in the kidney previously. Is that fair?
[Dr. Alana Desai]
I think that is a potential. Again, with these findings from the Mayo Clinic, it's tough to know whether stone formation itself is increased or just a symptomatic event. Again, with that stone passage, like you said.
(2) Differentiating Between Kidney Stones & Hydronephrosis
[Dr. Suzette Sutherland]
You used a term, I'm trying to think back to the term that you used, but hydronephrosis, I think of pregnancy is a term that we talk about. When you use that term, of course we could have hydronephrosis if we have an obstructing stone, but during pregnancy, are you just referring to the fact that the baby also is laying on the ureter during those later trimesters? Is there more to it in general, even during early pregnancy that it's common to see a slight hydronephrosis on one side or the other?
[Dr. Alana Desai]
Right. Both early in pregnancy, like I said, can occur up to as early as the sixth week of pregnancy. That's due to the increased progesterone that can be caused because of some of the ureteral dilation in itself. Then later in pregnancy is when hydronephrosis can be seen because of the gravid uterus itself. A mechanical obstruction, whereas in earlier pregnancy, it's this physiologic sort of response to the progesterone.
[Dr. Suzette Sutherland]
That's interesting because we often as urologists get referred these patients early on in their pregnancy. We know the fetus isn't that big yet. Pushing on the ureter causing the hydro, but we're being asked to evaluate them for a stent because they have some hydro. This is very important information to know that this is pretty common within six weeks already of pregnancy just because of hormonal changes.
[Dr. Alana Desai]
Exactly. Most people probably know this, but it is more common on the right side because of the production of the sigmoid colon on the left side. Up to 90% on the right side, it can occur in 67% on the left.
[Dr. Suzette Sutherland]
Then if we are suspecting that a pregnant woman, she's having some pain on one side or the other, how do we best differentiate between maybe they're just a little bit of hydronephrosis from the pregnancy versus a truly alarming, maybe obstructing stone? What's the best method of evaluation to start with?
[Dr. Alana Desai]
You have to start with your very basic history and physical examination. Again, as you said, you can't have leg pain just from pregnancy itself or back pain commonly. The most common presenting symptom of kidney stone disease is flank pain, about 80% to 100% present like this, followed by nausea and vomiting. Again, typical symptoms of pregnancy. You can also see other signs of stone disease such as microhematuria and gross hematuria, and then less commonly, fevers and chills.
Typically, again, you start with your basic history. Sometimes they'll tell you, I had an acute, sudden episode of pain in my back, and then it wrapped around to my abdomen, went to my groin. A little while later, I felt like I had to go to the bathroom. It just sounds like a classic stone history. That is very important. I think it's important to evaluate pregnant patients as you would a non-pregnant patient, taking those key events that happened during stone passage, and then, of course, considering the fact that there is a fetus involved. If there is fetal distress, then you have to take that into consideration. Initially, when you evaluate, it is much like a non-pregnant patient in taking that good history in laboratory evaluation as we normally would.
[Dr. Suzette Sutherland]
In the non-pregnant patient, and even in men, I think we very often quickly move to radiology, right? We just definitively want to know, is it a stone or is it not? What would you suggest here in the pregnant person?
In the pregnant patient, of course, the ultrasound remains the first line imaging modality with the ultimate goal of minimizing fetal radiation exposure. Both U.S. and international guidelines recommend ultrasound as first line.
(3) Stone Visualization & Imaging Modalities
[Dr. Suzette Sutherland]
Then we know that sometimes stones don't show up well on ultrasound, but of course, the thinking is if they're so small they don't show up, they're not going to be problematic. What size do you think makes that differentiating factor about whether it's really going to be a problematic stone or not, if you can see it on ultrasound?
[Dr. Alana Desai]
Sure. I think this varies by patient, body habitus, and stone size. As you said, a lot of stones don't show up on ultrasound. There are additional findings in the absence of actually visualizing a stone with an ultrasound. There are other features of ultrasound that we paid attention to in this diagnosis. One, hydronecrosis, of course, but you can evaluate ureteral presence, absence, delay. The other thing that people look at with pregnant stones is the resistive indices. It's a calculation using peak systolic velocity and diastolic velocity, using Doppler ultrasound. This can help distinguish true obstruction from physiologic hydronephrosis of pregnancy.
One of the other things you can use is the difference between kidneys. If there's a difference between more than 0.06 between resistive indices between kidneys, that's a very high sensitivity and specificity for obstruction of the ipsilateral kidney. In addition, like I said, to hydronephrosis and presence of stone, you can look at these other features of ultrasound and help improve the diagnostic accuracy of the ultrasound.
[Dr. Suzette Sutherland]
How easy actually in a pregnant patient who's farther along in her pregnancy is it to see ureteral jets, down low?
[Dr. Alana Desai]
They can just be missing in general and up to 15% of patients. It's not the only factor. When you're presented with a pregnant stone case, there's so many factors that you really try to hone in on to determine whether it is actually a stone or not. These are just the, sort of you take the constellation of historical factors, laboratory findings, imaging, and try to piece it together while reducing your risk to the mom and fetus or minimizing your risk.
[Dr. Suzette Sutherland]
If you're not finding anything definitively on with those modalities, but your suspicion is still pretty high, you have a pretty pained patient in front of you and your suspicion is high. When do you move on to CAT scan, radiation? What are the true radiation risks to the fetus with these modalities?
[Dr. Alana Desai]
Sure. Both AUA and EAU guidelines suggest MRI as a second line imaging modality without contrast. MRI using T2-weighted images can help to differentiate between physiologic and pathologic hydronephrosis during pregnancy. There are theoretical risks associated with this, such as the thermal effect of radiofrequency pulses, but the American College of Radiology have determined the dose to be safe in all pregnant patients. This is also recommended by the ACOG as well, saying that the teratogenic effects are minimal.
[Dr. Suzette Sutherland]
Do you find that today that is very widely used among general practitioners, MRI for stones?
[Dr. Alana Desai]
Yes, that is a good question. There are disadvantages owing to limited availability, especially after hours and prolonged acquisition time. There are certain protocols, like HAITH protocol, in which the test can be completed in less than 15 minutes. It is probably not widely used, but it is second line imaging. Now, low dose CT can be used as a second or third line option, but you do want to wait until at least the second trimester if you do need that. In the short term, the concern for radiation exposure are the potential teratogenic effects on the developing fetus.
Of course, this varies based on the radiation dose, the gestational age of the fetus. If one has to perform a CT scan, the best time to avoid it is between the second and 15th week of gestation when the radiation effects of the fetus are highest. Of course, appropriate patient counseling and involving the patient in this decision making process should occur. Longer term, there is some evidence that intrauterine radiation exposure can increase later risk of childhood cancers.
(4) Expectant Management of Kidney Stones During Pregnancy
[Dr. Suzette Sutherland]
Let's say we've made the diagnosis or you have a very strong diagnosis on ultrasound, you didn't have to move to the radiation. Now you're thinking about how are we going to take care of this patient? Clearly, just even in a non-pregnant patient, if expectant management is possible, that's what we're all rooting for and trying to support the patient through that as best we can.
Are there other specific things that we need to consider when we're helping a pregnant woman through expectant management? When is it that we should stop expectant because we're worried about maybe, is there a real risk of a woman going into preterm labor, as an example? Early on, maybe miscarriage. Is there any data to suggest that when a woman's having a lot of pain?
[Dr. Alana Desai]
Sure. The non-pregnant patient's indications for urgent intervention are going to be obviously infection or risk of sepsis. Fever, signs of sepsis. Clearly, urgent decompression is indicated. Other indications, bilateral obstruction, unilateral obstruction in a solitary kidney, renal insufficiency, intractable nausea, vomiting, and pain. In the pregnant patient, while you're monitoring, along with the obstetric team, the health of the fetus. If there's any fetal distress, that is also an indication for some form of intervention. As far as expectant management across the trimesters, it's going to be similar. Antiemetics, pain control, IV, and fluid hydration.
[Dr. Suzette Sutherland]
Are there certain pain medications that are favored during pregnancy versus others? Of course, we try to limit narcotics regardless, but sometimes we have to use them. When we look at the NSAIDs or Tylenol or other things, what's usually recommended first in pregnant patients?
[Dr. Alana Desai]
Tylenol is considered safe in pregnancy. NSAIDs, unfortunately, are contraindicated due to multiple risks. Risk of premature closure of the ductus arteriosus, oligohydramnios, and spontaneous abortion. Those are completely contraindicated. Low-dose and short-term morphine is considered safe. However, higher doses with longer duration can be associated with fetal narcotic addiction, intrauterine growth retardation, and premature labor. Short courses, low dose of morphine for pain control, and obviously Tylenol as well.
[Dr. Suzette Sutherland]
Like a Percocet or oxycodone falling into that morphine category, or you mean something specific?
[Dr. Alana Desai]
Yes, as an oral option or intravenous if needed for breakthrough.
[Dr. Suzette Sutherland]
Yes. In that whole category. Then how about for anti-nausea? Are there certain anti-nausea options that are more preferentially recommended during pregnancy? Sure.
[Dr. Alana Desai]
The antiemetics considered safe include antihistamines such as meclizine, phenergan, and compazine. Second line would be Reglan, something like a dopamine antagonist. They can be associated with extrapyramidal side effects. Those are second line. Zofran is also considered second line owing to limited data on its use. Again, the first line is going to be those antihistamines and methiazines.
[Dr. Suzette Sutherland]
Okay. Then what about the use of Flomax? Of course, we try to use that to help with that delivery of the stone, so to speak. Is it contraindicated in pregnancy or can we use it safely during pregnancy?
[Dr. Alana Desai]
Flomax, since there is still a debated use even in the non-pregnant patient, there has been some evidence that it's useful for stones greater than 5 millimeters in the distal ureter. There's still a matter of debate. I believe it's considered a category B medication. Correct. It can be used. However, again, because there's a consensus that is lacking, there is also a recent retrospective study of pregnant patients receiving MET that showed no significant increase in stone passage compared to those not receiving it and no reduction in the need for surgical intervention. Based on current consensus lacking and non-significant findings in pregnant patients, as of late, MET is not routinely used in kidney stone disease. However, again, as you said, it's category B, so it's safe to use.
(5) Surgical Interventions: Ureteral Stent vs. Percutaneous Nephrostomy Tube
[Dr. Suzette Sutherland]
Relatively speaking, yes. Then I guess 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]
If you do have the equal capabilities, so the percutaneous nephrostomy tube can be done under just some local anesthesia, but if you're changing a stent, usually, we're doing that under a little bit of IV sedation, some general anesthesia. I don't know if it's been done with even less than that if it has to be done every four weeks. What are your thoughts on that?
[Dr. Alana Desai]
If anesthesia is needed, preferably, it's after the first trimester. Second trimester is best one to reduce radiation and anesthetic exposure to the developing fetus and then trying to avoid it in the third trimester so that you don't have patients going to preterm labor, so the second trimester is the best time for intervention. General anesthesia is typically utilized. Spinal anesthetic has also been described as well as even MAC in select cases.
[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.
(6) Utilizing Ureteroscopy During Pregnancy
[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.
[Dr. Suzette Sutherland]
We have different modes of doing ureteroscopy, predominantly doing just flexible ureteroscopy, but there's the semi-rigid. If somebody has a stone that's in the distal ureter or lower third, would you consider using a semi-rigid on the woman who's pregnant as well or just stay with flexible?
[Dr. Alana Desai]
Semi-rigid is possible in the distal ureter. It's a bit easier to use in the distal ureter as we know, but I have used a flexible scope in the distal ureter. If the ureter did not accommodate the semi-rigid, I would have used that.
(7) Indications of Percutaneous Nephrolithotomy (PNCL) in Pregnant Patients
[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 because I actually have had to perform a PCNL in a pregnant patient. It was in a semi-urgent fashion. If you want to hear about it, it's kind of interesting.
It was a patient who for social reasons ended up having an urgent nephrostomy tube placed during her ninth pregnancy and she due to drug and alcohol problems was leaving AMA each time she would get her kidney decompressed and then leave. This was her ninth and tenth pregnancy, so she encrusted her ninth pregnancy stent delivered and she came back with that stent encrusted, and lo and behold she was pregnant again.
They placed the second nephrostomy tube to decompress and the same scenario kept happening over and over during this pregnancy and finally, that second nephrostomy tube encrusted which is when I got called by the interventional radiologist and she said her name, "Do you know this patient?" and I had not heard of her, and he said, "I cannot believe you don't know who this is. She comes in every week and this is the story. Now, we can't get the second tube out and she's so encrusted that both tubes are stuck in there. Can't you help us?"
She indeed had such a large stone that she would require a perc. I think she was in her third trimester probably about 33 weeks or so and I did know that doing it ureteroscopically would have taken a prolonged amount of time and that was most likely the right approach to do it expeditiously, but there is no way to exchange her tubes without doing some sort of stone procedure. I was sort of pressured to do her stone the day she came in with potential sepsis. "Can you just do it now because she's going to leave AMA and so?" Although it was a team effort, I did not believe that just because there's this potential social situation, we should operate on an infected patient.
We still have to manage pregnant patients in a safe way, so I did recommend treating the infection appropriately before proceeding with PCNL and the team said, "Well, she's not going to come back." The best I could I counseled her that this is what could happen if you don't return on antibiotics and it was kind of a long talk, but I said, basically, I will be there if you'll be there, and she showed up, and we were all very nervous. We did a modified lateral position where I could manage her ureteroscopically and percutaneously. It was all done under ultrasound.
We were able to watch it come in from below very expeditiously removing the tube stone and left her with one nephrostomy tube and then watched her for overnight and then removed the nephrostomy tube just to get her tube free. It was a little bit of a dramatic story but I do think that, in her case, it was the best procedure to perform. It took probably about 30 minutes to clear her and get those tubes out and ureteroscopically, it would have taken hours upon hours and most likely two procedures. I did feel that was the right move on that patient but, again, I was surprised that there was such a little amount done but, no. To answer your question, it is contraindicated unless there are extreme conditions and I do think this did qualify as extreme.
[Dr. Suzette Sutherland]
That was definitely an extreme condition. A lot of social determinants of health there that came into play there and just trying to put the pieces of the puzzle together to come up with what's the right answer here, so kudos to you for taking that on. That's great. Very challenging case. 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.
(8) Preventing Kidney Stones During Pregnancy
[Dr. Suzette Sutherland]
Then with respect to prevention, are there specific recommendations that can be made to pregnant women who maybe already have a known history of recurrent stone formation? They've already had three stones in their life and now they're pregnant. You probably assume their risk is a little higher than the average. Are there different recommendations or do we stick to our basics of making sure you're drinking enough, a low oxalate diet, low salt, or are there specific pregnancy tailored recommendations out there?
[Dr. Alana Desai]
You mean for patients who are already pregnant with a known, they have a known stone burden or a known history of?
[Dr. Suzette Sutherland]
They have a known history of stones and we want to make sure they don't develop a stone while pregnant or maybe have it move during pregnancy.
[Dr. Alana Desai]
Got you. Now I think just the general recommendation of plenty of fluids, trying to produce two and a half to three liters of urine per day, following a low sodium diet, avoiding sugary drinks, sodas, things like that, potentially a low oxalate diet. I think taking calcium in with their meals in case they have a high oxalate load, but not any different than the general population.
There is a question of should, sort of a more esoteric question, should women of childbearing age with known stones, if they're considering pregnancy, should they clear their stones prior to trying to conceive? I think we would all like that option, actually. Yes, you're probably just a patient electively treating their stones before becoming pregnant, but that is a question for another day.
[Dr. Suzette Sutherland]
Truly, is that done that often? I know that there are women who want that done, but there are lots of reasons why someone wants electively to have a stone removed. They've had a stone for a long time and now they're going to go on this big worldwide tour and they're like, dang it, I don't want to lose that stone or have it get stuck when I'm in Morocco. Can we just take care of it now, right? I imagine, yes, if you have women who do have known stones, yes. Is that done that often now?
[Dr. Alana Desai]
Oh, definitely. I think if there were a patient who, similar to a patient who is going to Morocco, wanted to have their stones re-electively saved, they wouldn't have to deal with it during an opportune time. I think we would definitely consider that. It's currently not, I don't want to say, not standard of care, but if a patient comes in, we don't necessarily have to have their stones removed electively prior to pregnancy.
Depending on the size, we may say it's a good idea, but currently there are no guidelines that say we have to treat these stones prior to pregnancy. I do think it would be ideal to do so that the patient and provider and developing fetus do not have to deal with an acute stone episode during pregnancy. I think that would be a reasonable way to counsel patients considering pregnancy that have known stones. I do think that'd be completely reasonable.
[Dr. Suzette Sutherland]
The last thing we want is a worrying fetus.
[Dr. Alana Desai]
Correct.
[Dr. Suzette Sutherland]
Great. That's been a lot of helpful information. I think, a big take home from this is really the wide use of ureteroscopy and immediate stone intervention and removal when possible, if it can be done rather expediently by someone who has good training in ureteroscopy, right? That just because the woman is pregnant, it doesn't mean that you can't take care of her stone definitively, and I think that's really a huge piece of information. I know that's been done for a while, but there's still a lot of controversy out there among general urologists, I think, that still shy away from the pregnant patient.
[Dr. Alana Desai]
I think that is reasonable. That's one other important key because the AUA guidelines are clear that ureteroscopy in the pregnant patient should only be performed if the surgeon is comfortable with this and adept with the procedure and has adequate perinatal and obstetric support available, and that's not always the case. If the patient needs to be transferred for definitive care, that transferring is a reasonable option.
[Dr. Suzette Sutherland]
Yes. You brought up a good last point, is that certainly involving OB in this is just of utmost importance, right? Having OB there, somebody to monitor the fetal heart rate during the procedure is just, I'm sure that's a recommendation there on guidelines somewhere too, I'm sure. That's really important so that you're in constant communication so that we're all ready should something go awry, right?
[Dr. Alana Desai]
Correct. Not only between the urologist and obstetric team, radiology and aesthetic teams as well, so.
[Dr. Suzette Sutherland]
Yes, very good. Good. That was wonderful. Any other parting words? Are there any other topics about this that you wanted to address that I didn't ask you about?
[Dr. Alana Desai]
I think we covered most of it. I guess having a clear local pathway, including service to be admitted to, OB versus urology, imaging, treatment plan, whether the facility is indeed capable of managing that patient and whether transfer is necessary. I think all of that needs to be having a protocol up front, a clear protocol for each institution or hospital to avoid unwanted delays in delivery of care.
[Dr. Suzette Sutherland]
We always find that when we have all of our ducks in a row, we don't need them.
[Dr. Alana Desai]
Correct.
[Dr. Suzette Sutherland]
It's when the ducks aren't ready that we suddenly find ourselves wishing we were a little more prepared, right?
[Dr. Alana Desai]
That's right.
[Dr. Suzette Sutherland]
In this situation, you really need to make sure your ducks are in a row because there's more than just the patient, the fetus at stake too here, so good. Thank you so much. Thanks for sharing your expertise and your firsthand experience with us. That was really wonderful.
[Dr. Alana Desai]
Thank you again for the opportunity. Nice to see you as always.
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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