We learn about the etiologies of prenatal hydronephrosis, and postnatal evaluation and management of these newborns. We are joined by Irina Stanasel, MD, Assistant Professor of Pediatric Urology at the University of Texas Southwestern Medical Center.
Dr. Neeta Goli:
Welcome to Newborn News, a podcast where we discuss educational topics from medical professionals who care for newborns. I'm your host, Dr. Neeta Goli, a pediatrician in the UT Southwestern Newborn Nursery. Welcome back to the podcast. In today's episode, we will be discussing congenital urinary tract dilation. We are recording remotely due to the ongoing COVID pandemic. We are joined today by Dr. Irina Stanasel, Assistant Professor of Pediatric Urology at UT Southwestern.
Dr. Irina Stanasel:
Hello?
Dr. Neeta Goli:
Hi, Dr. Stanasel. Thanks for joining us today.
Dr. Irina Stanasel:
Good morning. Thank you for having me.
Dr. Neeta Goli:
Urinary tract dilation or UTD, also referred to as hydronephrosis, may sometimes be noted on prenatal ultrasound. In today's episode, we'll learn how to evaluate and manage these infants with this history. To start off with, how common is this finding on prenatal ultrasound?
Dr. Irina Stanasel:
So it's actually quite common. It is the most common abnormality that can be seen on a prenatal ultrasound. The percentage of pregnancies that are found to have renal dilation can sort of vary depending on how exactly you define it, but overall, I think probably about 1% is a good estimate of how often we see prenatal hydronephrosis.
Dr. Neeta Goli:
What are some of the potential etiologies?
Dr. Irina Stanasel:
So when you talk about hydronephrosis or dilation within the collecting system of the kidney, we talk about urine being in the kidney that basically is not transmitted down into the bladder quite as fast as you'd expect. That can just be completely physiologic. It's just the way that I explain it is the funnel that catches the urine as it's made from the kidney and the ureter that sends it back down into the bladder, that can just be a little bit bigger or a little more dilated, but there's actually no pathological cause. That can just be perfectly normal. That's actually probably the most common thing that can cause the dilation, just absolutely no etiology. It's just a dilated system without any actual problem, but the things that we do have to be concerned about and think about and rule out or check for are things like obstruction.
Dr. Irina Stanasel:
If there is urine that is in the kidney or in the ureter that should be draining faster, that could be because of an obstruction or a blockage. That can be at the ureteropelvic junction area or at the ureterovesical junction area or even further down than that, down in the urethra especially in boys. In boys, we have to always be concerned about a urethral blockage and even if the dilation is just in one kidney, it's always in the back of my mind because that's one of the most important things to rule out and address quickly after a baby is born. It can also be because of reflux. So if you have urine in the bladder that is refluxing back up into the kidney and into the ureter, that can cause stretching out of the system and cause dilation with kind of pooling of the urine in the system. It's a kind of opposite problem of obstruction. Things are flowing backwards more than you'd like. So those are the main things: physiologic, obstruction, or reflux.
Dr. Neeta Goli:
Then when urinary tract dilation is reported, what other prenatal ultrasound findings should we really look at carefully?
Dr. Irina Stanasel:
So hydronephrosis is also often identified in conjunction with other abnormalities. So of course a thorough assessment of the fetus is important, but other things specifically urological that are of interest are things like oligohydramnios. If there is obstruction and especially if the baby has obstruction of both kidneys, one very important thing to consider is whether or not there is enough urine being produced to maintain good fluid levels. That has a lot of implications for prognostic reasons and even for prenatal management reasons. The indications for any kind of prenatal intervention because of hydronephrosis and urinary tract dilation are actually very few, but one really important thing to consider when talking about, well, is this something that would have to be addressed even before the baby is born, is if there is a good fluid level.
Dr. Irina Stanasel:
If you're talking about urinary tract dilation in the setting of oligohydramnios, that's a time when you may want to consider prenatal urological counseling or maternal-fetal medicine consultation. That's kind of a different situation than when you're talking about good fluid levels, maybe one kidney dilated. Even if it's severe, there's really not much to do until the baby gets here. So again, the times when you would actually consider doing something like having the baby be delivered sooner than you would want or having some kind of a shunt placed to divert the urine from the bladder to the amniotic space, it's very, very rare, but those are just things to think about and consider and times when you may want to consider a consultation.
Dr. Neeta Goli:
Then when these babies are born, what should we pay attention to on their physical exam?
Dr. Irina Stanasel:
So of course just the full genitourinary exam and honestly, it will be very rare that you would identify anything that would be abnormal on physical exam. You're more likely to find a normal exam, but certainly identifying a patent meatus, a patent urethra, and a full GU exam in a boy, the position of the testicles, is the phallus fully formed, is the anus properly positioned, is the abdomen distended, does the abdomen have a normal appearance, is there a wrinkly or prune-belly type appearance, are all very important. And similar in a girl, is there a well-placed urethral meatus and vaginal opening? Is there any sign of a urogenital sinus or a persistent cloaca or are all orifices where they should be? Is the abdomen distended, those kinds of things?
Dr. Irina Stanasel:
Another thing to kind of pay attention to, but almost be very careful not to be too comfortable if you see it is: is the baby voiding. Of course when you're talking about a urinary tract problem like dilation or really anything where you're suspecting obstruction, you're paying attention to all of the urinary tract issues that are going on with the child. So you want to take note of when the baby is voiding. If you are able to see a stream especially in a boy, that would be good to note, but the one thing that I would caution is actually those things, regardless of what's going on, those things are actually likely to be there.
Dr. Irina Stanasel:
When you think about it, the fetus has gotten through the pregnancy. The amniotic fluid levels have been maintained to some degree at least up until the birth. So the baby has been able to void. The baby will most likely continue to void, but that does not rule out significant pathology and we cannot get too comfortable just saying, "The baby's voiding. Things must be okay." So it's actually kind of opposite of what you would think. You're not looking for a good exam and voiding and all that and you're checking off those boxes to feel comfortable. It's important to check them off, but it's important not to get too hung up on that ruling out significant issues.
Dr. Neeta Goli:
So assuming, like you mentioned, that we do have a baby with a normal exam and a baby who is voiding, what else should we do for these babies?
Dr. Irina Stanasel:
A renal ultrasound is very important in the first couple days of life in a baby who has had prenatal hydronephrosis, and that tells us a lot. It doesn't tell us everything. Sometimes things progress in the first few weeks or few months of life. So certainly if the imaging is at all abnormal, I recommend repeat imaging usually at about six weeks of life, but it does tell us a lot in the first couple of days. That is very important to get. Depending on what the ultrasound shows, we can make determinations about whether or not other studies should be done after that.
Dr. Irina Stanasel:
Most people say the first postnatal ultrasound should be done at about 24 to 48 hours of life, and I think that that's really a reasonable goal. I don't think we need to be so, so strict about it. The babies tend to be a little bit dehydrated in the first 24 to 48 hours of life and we think that may underestimate the hydronephrosis a little bit. So that's why most people say to wait and get the ultrasound after a couple of days, but to be honest, we also can kind of use common sense a little bit. If a baby had really abnormal prenatal findings, especially if these babies have bilateral significant hydronephrosis, a dilated bladder, and we're already concerned for some valves or urethral pathology, there's no need to wait. They had those findings prenatally; they will have it postnatally even in the first 24 hours. So it's not such a strict cutoff, but if there's no significant concern, I think waiting and getting it closer to the time that you'd be discharging the baby from a hospital is a little more reasonable.
Dr. Neeta Goli:
You mentioned severe hydronephrosis. What is the classification scheme for urinary tract dilation severity?
Dr. Irina Stanasel:
Sure. So it depends a little bit on exactly when you were looking at the dilation. So if you're talking about having measured the dilation in the second trimester, for example, what I would classify as severe is more than ... In the classification system, is more than 10 millimeters of dilation at the level of the pelvis. So the anterior to posterior diameter of the pelvis more than 10 millimeters in the second trimester would be considered severe. In the third, it would be more than 15 millimeters. So that's sort of as much as we can try to standardize when we talk about these things to give it some number, some objective measure, and we look at the anterior to posterior diameter of the pelvis.
Dr. Irina Stanasel:
But overall, really there are multiple things that can be taken into consideration when you're thinking about the severity of the situation. So for example, in boys with bilateral hydronephrosis, I'm a lot more concerned than in girls with bilateral hydronephrosis because I'm always worried about urethral pathology. That is something that would have to be addressed right away after birth. You really cannot discharge a baby home with urethral pathology. That's something that we have to rule out. If we at all suspect it, the baby needs not just a renal ultrasound but a VCUG before leaving the hospital. So I'm more worried about hydronephrosis in boys than in girls. I'm more worried in bilateral hydronephrosis than I am in unilateral, and I'm more worried if the ureter is dilated than if it's just the kidney.
Dr. Irina Stanasel:
So although the classification system for severity really only takes into consideration the anterior to posterior diameter when you're talking about the severity of the prenatal hydronephrosis, taking all of these things into consideration is important. So hydroureteronephrosis in a boy especially if it's bilateral is very suggestive of urethral pathology, which is about the most important thing to rule out at birth, but other things can cause it also especially if it's unilateral, such as the ureterovesical junction obstruction or reflux. They're frankly more common and it's the most likely cause of hydroureteronephrosis, but kind of always thinking of the worst case scenario, we want to make sure that we rule out the things that need to be surgically addressed right away and the most common one would be urethral obstruction such as valves in baby boys.
Dr. Neeta Goli:
When do you all recommend that babies be discharged home on prophylactic antibiotics?
Dr. Irina Stanasel:
So that's a little bit more of a controversial topic. So the idea with prophylactic antibiotic would be really to minimize the risk of infection if the babies have or we think they may have reflux. For example in babies who have mild hydronephrosis without dilated ureters, the chance of them having reflux and have this not just be the physiologic hydronephrosis that we were talking about is actually fairly low. So it used to be that all these babies with hydronephrosis were put on prophylactic antibiotics and had a VCUG and if the VCUG ruled out reflux, then you could stop the prophylactic antibiotic. That's still a fairly conservative thing to do and it's certainly not wrong, but recently the data is really suggesting that that may be overkill.
Dr. Irina Stanasel:
So if the babies have mild hydronephrosis that is just in the kidney without dilated ureters, it is probably reasonable to go ahead and discharge them without antibiotic and without a VCUG and just have them follow up in four to six weeks with a renal ultrasound to assess the degree of dilation and proceed accordingly. Now if the babies have hydronephrosis that is a little more severe like moderate to severe hydronephrosis at birth and if they have ureteral dilation or if the bladder looks abnormal, then certainly prophylactic antibiotics would be reasonable at that time and if possible, it is best to just go ahead and get a VCUG before they even leave the hospital. That could kind of tell you if you really are needing the antibiotics or not, but sometimes the feasibility of getting a VCUG right at birth is just not there.
Dr. Irina Stanasel:
The babies can be born somewhere where they're not offering VCUGs or where they don't do them frequently and it makes it a little bit tough to get. So it's just discharging the baby on a low-dose amoxicillin dose of prophylactic antibiotic and having them come to clinic to determine whether or not we should proceed with a VCUG or just go ahead and stop the antibiotic is also a reasonable thing to do. I think it's very important of course to caution the family about return precautions for any signs or symptoms of urinary tract infection regardless of whether or not we're starting the prophylactic antibiotic. The prophylactic antibiotic lowers the risk of urinary tract infection, but it does not bring it down to zero, so that's always a concern.
Dr. Irina Stanasel:
But babies who have just mild hydronephrosis without dilated ureters with normal bladders are unlikely to be at any higher risk of getting a UTI compared to really any other babies. So should we be starting all those babies on prophylaxis? Probably not. The ureteral dilation certainly does suggest that there is a little bit of a higher risk of having reflux and even if the underlying pathology is ureterovesical junction obstruction, a little bit higher risk of UTI there too. So putting those kids on prophylaxis is reasonable. I think that calling the urologist on-call and kind of running the ultrasound findings by us and having us help guide whether or not we really think a VCUG is necessary while the baby is in the hospital or exactly what the timeline of follow-up should be. For some babies I'm probably a little more comfortable with a longer first follow-up with urology like three months, and some babies I'm just a little bit more concerned about and I push that six week even a little closer and I say, "Let me just see them in two to three weeks and let's make sure this isn't rapidly progressing or anything like that." So we're always here and always happy to help guide that follow-up plan.
Dr. Neeta Goli:
Then what is a typical prognosis for babies with urinary tract dilation assuming it's not part of a larger syndrome?
Dr. Irina Stanasel:
So it's very varied. Over the years, we've become less interventional with a lot of these conditions. So again, the most common things being obstruction of some sort, the ureteropelvic junction, the ureterovesical junction, or reflux. A lot of these conditions used to prompt surgical intervention decades ago, and now we've realized that actually even if they do have some degree of ureteropelvic or ureterovesical junction obstruction, that a lot of these babies actually tend to open these up by themselves in the first few months to few years of life. So a lot of them we just monitor them with ultrasound and ensure that they're progressing in the right direction and get other studies if indicated like renal function studies, MAG-3 renal function studies to assess the degree of obstruction or DMSA scans to assess the very specific function of the kidney.
Dr. Irina Stanasel:
Sometimes that's all it takes is monitoring, and that's really, at least for ureteropelvic junction obstruction for example, whereas most of these used to have surgical intervention now about 80% of them ... It depends on what study you're reading, but overall about 80% will tend to resolve by themselves. This hydronephrosis just improves by itself or does not seem to cause a cause for concern, does not seem to be damaging the kidney and does not need surgery. So surgery certainly may be in the future for these kids, but a lot of it is just monitoring. Similarly with the reflux, a lot of reflux we used to think of it as a very surgical disease and now, we monitor these kids sometimes on prophylactic antibiotics, sometimes off of prophylactic antibiotics and watch the kids for a few years and a lot of the reflux does tend to go away depending on the grade and they don't end up needing surgery. So surgical intervention is certainly an option and it may be necessary for some of these kids, but a lot of them won't need surgery and the prognosis is actually really quite good.
Dr. Neeta Goli:
That's really encouraging.
Dr. Irina Stanasel:
Yes, it is. I think that the most important part about urinary tract dilation is proper monitoring and response to each individual child and each individual family really. It's one of these things where if the family is comfortable with a particular course of action, you just have different options for managing different things. If it's a family who lives near a hospital and they're able to bring the child in frequently if necessary if there's any sign of infection, then certainly a lot of things like reflux and dilation I am happy to monitor longer than if a family says, "The child is not taking antibiotics. I have a hard time getting the child to a healthcare provider if there is an urgency such as a febrile UTI." Then sometimes surgical management is actually the more conservative route to go. So I think as long as we are appropriately catching these patients early, especially prenatally, and responding to the needs of each individual child, the prognosis can really be quite good in a lot of these kids.
Dr. Neeta Goli:
How should we counsel these families before they see you all in urology?
Dr. Irina Stanasel:
I think the most important thing is bringing them to the emergency room or to the pediatrician seeking help early if they seem sick and counseling them to the signs of urinary tract infection. Certainly a fever in a baby of less than a couple months of age should prompt an immediate evaluation, but blood in the urine, urine that has a strong odor or looks purulent, kind of anything different, if the baby's acting lethargic or anything like that can be a sign of underlying urinary tract problems. So counseling them about those things I think is very important.
Dr. Irina Stanasel:
Another thing is if we have made a decision in conjunction with urology or without urology that the baby should stay on a prophylactic antibiotic, I think ensuring that the baby has a prescription that is lengthy enough to get them through their follow-up with urology is really important. So I'd make sure that the prescription for their prophylactic amoxicillin has adequate refills. Especially right now, it may be harder for people to get around with COVID and everything, harder to get into healthcare provider's office or for them to get out of the house or whatever. So they may not get to their follow-up exactly when we're hoping they'll get to their follow-up. So we want to make sure that they're adequately supplied with their preventative antibiotic if that decision has been made. I think that would be very helpful and yeah, just ensure that they do follow up with the urologist.
Dr. Irina Stanasel:
I think that sometimes parents and healthcare providers get a little excited when we see some imaging postnatally that looks fairly reassuring, but if there's been a cause for concern such as fairly significant hydronephrosis prenatally and we get a postnatal ultrasound that shows mild hydronephrosis, well we know that the problem is not that bad, right? Because otherwise it would show itself even at 24 hours like I said, but sometimes that's just an underestimate. So it's still super important to keep that follow-up that they've been given with a urologist. So counseling them about that is really important.
Dr. Neeta Goli:
To end the episode today, do you have any advice for our listeners while they take care of newborns?
Dr. Irina Stanasel:
I think that my biggest advice would be: don't be afraid to reach out to urology. We're here. We take phone calls all the time about newborn babies who have had prenatal findings and now they have an ultrasound or they don't have an ultrasound or they have a VCUG and they want some guidance. We are absolutely here. This is what we do all the time. So taking a quick phone call and helping guide this follow-up plan, if that relieves stress for the provider and makes the family feel more comfortable, don't ever be afraid to reach out to us.
Dr. Neeta Goli:
Dr. Stanasel, thank you so much for joining us today.
Dr. Irina Stanasel:
Thank you so much for having me. This has been a pleasure and yes, please feel free to always reach out to me if you have any questions or if there's anything I can do to help.
Dr. Neeta Goli:
Thank you. Thanks for listening to Newborn News. We hope you join us next time. If you like what you hear, make sure to subscribe and leave us a review. If you have questions, comments, feedback, or suggestions for future episodes, please email me at NewbornNews@utsouthwestern.edu. As a reminder, this content is educational and is not meant to be used as medical advice. Views or opinions expressed in this podcast are those of myself and my guests, and do not necessarily reflect the views of the university.