Prenatal Hydronephrosis is the most common condition identified in babies during prenatal ultrasounds.
Learn more about Prenatal Hydronephrosis, including the available treatments, from a specialist in pediatric urology at UVA Children's Hospital.
Selected Podcast
Understanding a Common Prenatal Condition
Featured Speaker:
Organization: UVA Children's Hospital
Dr. C.D. Anthony Herndon
Dr. C.D. Anthony Herndon is a specialist in pediatric urology who serves as Director of the Division of Pediatric Urology at UVA Children's Hospital.Organization: UVA Children's Hospital
Transcription:
Understanding a Common Prenatal Condition
Melanie Cole (Host): Prenatal hydronephrosis is the most common condition identified in babies during prenatal ultrasounds. My guest is Dr. Tony Herndon. He's a specialist in pediatric urology, who serves as the Director of the Division of Pediatric Urology at UVA Children's Hospital. Welcome to the show, Dr. Herndon. Tell us a little bit about this prenatal condition that most people have not even heard of.
Dr. Tony Herndon (Guest): Thanks for having me on today. Prenatal hydronephrosis is the identification during the maternal fetal or the obstetrician ultrasound of the mother, where the baby inside of the mother has fluid on the kidney or dilation of the kidney. There are varying grades of this. The most common is grade one, which is very minimal fluid on the kidney, and the most severe is grade four, and that's less common. That's where the fluid causes tension to the point where it compresses the normal kidney tissue, and that can be seen fairly readily with an ultrasound because the fluid is actually urine. That's very easy to discern. That's one of the reasons it's the most common condition diagnosed. It's easy to pick up.
Melanie: What causes it, Dr. Herndon? If urine is putting pressure on his kidney, pregnant women have enough pressure going on in all sorts of places anyway. So you spot this on an ultrasound, what is the cause?
Dr. Herndon: Well, I have a discussion with the families directed at that. The most common cause is transient, actually. There's fluid that builds up on the kidney, and if you follow the kidneys throughout pregnancy, in about two-thirds to 70 percent, most of those kidneys normalize within the first six months postnatally. Almost all of these kids, as a whole, you can assure the families that everything's going to be okay. There's a subset of kids that have a specific diagnosis that puts them at a little bit higher risk of an infection, the need for surgery, or kidney damage. The issue though is you can't always sort those kids out prenatally, and that's done based on postnatal testing. We have a risk stratification that we use that puts them in kind of a low, medium or high risk, and depending on the risk, that prompts things such as the need for preventative antibiotics postnatally, invasive testing, where we would actually put a little tube in the bladder and inject dye to look at the bladder anatomy, or do further imaging of the kidneys to look at drainage and function.
Melanie: So this is what happens during pregnancy. How does it affect the newborn?
Dr. Herndon: Well, the newborn, during pregnancy, the mother is providing kidney functions. So in terms of the kidney functions, it's very uncommon for us to do anything or have the need to do anything prenatally because the mother is providing the kidney function. In a very select subset, the baby is not urinating, and the urine, during pregnancy, allows fluid to go around the baby and the lungs to develop. That's the only condition that we actually do something prenatally. That's the first thing that we tell the families. Then we check off the list that there's plenty of fluid, amniotic fluid, around the baby that we can safely follow the baby postnatally. When the baby is born, we need to do a kidney ultrasound of the baby, very similar to what the mom had, an ultrasound, and that's done before the baby leaves the hospital. That sets the tone for further testing. Some kids need to be followed very, very closely, and some kids, as I mentioned previously, might resolve or significantly downgrade their kidney dilation.
Melanie: After the baby is born, you do an ultrasound of the baby's bladder, kidneys, and then you kind of keep a watch on them. What could happen, Dr. Herndon? Could they reflex back up into the system? Could they sort of be toxic, a little bit?
Dr. Herndon: Well, the kids—and that's where this risk stratification comes into play—as a group, as a whole, pediatric urologists have tried to get away from using preventative antibiotics. It's developed this risk stratification [I have] to try and classify kids into groups that are at low risk of infection, and that's based on the degree of kidney dilation that we see prenatally. Kids who are at moderate risk and high risk, those kids, if they do have urine that backs up, which is one of the [ideologies], they're at high risk of having kidney infection and toxic, like you said. If they're at low risk of infection, even if they do have urine that backs up, they're probably not going to get infected, hence not become toxic. That's the tricky part is we don't study every child. If we did, we would pick up disease in kids that might not necessarily have an issue with it. They keep up with this disease. One of these conditions is reflux, where the urine backs up. Those kids are managed with long-term antibiotics. We're trying to get away from that.
The other ideology is kidney obstruction. But luckily, those kids predominantly have severe kidney dilation, grades three and four, so those kids, we kind of know based on that ultrasound. The kids that tend to get that trouble, we kind of have a lead on that, because of the severity of the kidney dilation in terms of the kidney blockage. Kids that have urine that back up to the system reflux, the ultrasound helps us classify the risk of infection, and that's what directs the intervention with the invasive testing to diagnose the urine that backs up to the kidney.
Melanie: For the most part, are they able to filter this out when you see? Of course, you can't study every baby, but are they able to filter this out? If they're not, is there surgery required? Are there other certain other interventions besides the long-term antibiotics?
Dr. Herndon: Sure. Going back to the ideologies, the most common is transient, meaning it does go away. That takes care of 70 percent. The urine that backs up the reflux, those kids typically do well that are picked up prenatally. If you look at that group, they get infected, but at a much lower rate than kids that present later in life with reflux and infections. Infections, when you're dealing with urine that backs up to the kidney, that drives surgical intervention, not necessarily the presence of urine backing up. Some of those kids will have surgery, probably about 20 percent because of infections, but a little bit depends on the severity of urine backing up. Kids that have the same volume that's in the bladder backing up to their kidneys, those kids are more likely to have surgery. Kids that have minimal urine backing up from bladder to the kidneys are less likely to have surgery. That group of refluxing patients, that's what we call that Vesicoureteral reflux. Those kids, they're a spectrum; most kids will not need surgery, but a subset will, and those are the same kids that are getting infected or have very high-grade reflux.
Melanie: Dr. Herndon, these babies in the prenatal NICU, are they, when they're born, they've got this condition?
Dr. Herndon: No. Most babies are not. Most babies are born on the regular ward, and a small subset will be delivered in the NICU, but that's very uncommon. Most of these babies are delivered at community hospitals, or they might be delivered at UVA. They have an ultrasound after the baby's born. Most of this work up is done as ambulatory, so in the clinic. They would come back and see me at one month, and we would repeat the ultrasound. If the patient is one of those moderate- to high-risk stratifications, then we would have the invasive testing, where we slip a little catheter in the bladder and use contrast to determine if urine backs up to the kidney, or if there's an abnormality with the urethra, the tube that leads from the bladder.
Melanie: Dr. Herndon, in the last 20 seconds or so, explain to the listeners why they should choose UVA Children's Hospital for care for this condition.
Dr. Herndon: One of the reasons is we offer a multi-specialty approach. I run a prenatal clinic with maternal-fetal specialist, Chris Chisolm and his group here at UVA. That gives us the opportunity to meet the families prenatally and to meet the mother and to explain to her what the risk stratification is for her baby. And then that allows one, for education; and two, for her to know what to expect postnatally.
Melanie: Thank you so much. You're listening to UVA Health System Radio. For more information, you can go to uvahealth.com. This is Melanie Cole. Thanks for listening.
Understanding a Common Prenatal Condition
Melanie Cole (Host): Prenatal hydronephrosis is the most common condition identified in babies during prenatal ultrasounds. My guest is Dr. Tony Herndon. He's a specialist in pediatric urology, who serves as the Director of the Division of Pediatric Urology at UVA Children's Hospital. Welcome to the show, Dr. Herndon. Tell us a little bit about this prenatal condition that most people have not even heard of.
Dr. Tony Herndon (Guest): Thanks for having me on today. Prenatal hydronephrosis is the identification during the maternal fetal or the obstetrician ultrasound of the mother, where the baby inside of the mother has fluid on the kidney or dilation of the kidney. There are varying grades of this. The most common is grade one, which is very minimal fluid on the kidney, and the most severe is grade four, and that's less common. That's where the fluid causes tension to the point where it compresses the normal kidney tissue, and that can be seen fairly readily with an ultrasound because the fluid is actually urine. That's very easy to discern. That's one of the reasons it's the most common condition diagnosed. It's easy to pick up.
Melanie: What causes it, Dr. Herndon? If urine is putting pressure on his kidney, pregnant women have enough pressure going on in all sorts of places anyway. So you spot this on an ultrasound, what is the cause?
Dr. Herndon: Well, I have a discussion with the families directed at that. The most common cause is transient, actually. There's fluid that builds up on the kidney, and if you follow the kidneys throughout pregnancy, in about two-thirds to 70 percent, most of those kidneys normalize within the first six months postnatally. Almost all of these kids, as a whole, you can assure the families that everything's going to be okay. There's a subset of kids that have a specific diagnosis that puts them at a little bit higher risk of an infection, the need for surgery, or kidney damage. The issue though is you can't always sort those kids out prenatally, and that's done based on postnatal testing. We have a risk stratification that we use that puts them in kind of a low, medium or high risk, and depending on the risk, that prompts things such as the need for preventative antibiotics postnatally, invasive testing, where we would actually put a little tube in the bladder and inject dye to look at the bladder anatomy, or do further imaging of the kidneys to look at drainage and function.
Melanie: So this is what happens during pregnancy. How does it affect the newborn?
Dr. Herndon: Well, the newborn, during pregnancy, the mother is providing kidney functions. So in terms of the kidney functions, it's very uncommon for us to do anything or have the need to do anything prenatally because the mother is providing the kidney function. In a very select subset, the baby is not urinating, and the urine, during pregnancy, allows fluid to go around the baby and the lungs to develop. That's the only condition that we actually do something prenatally. That's the first thing that we tell the families. Then we check off the list that there's plenty of fluid, amniotic fluid, around the baby that we can safely follow the baby postnatally. When the baby is born, we need to do a kidney ultrasound of the baby, very similar to what the mom had, an ultrasound, and that's done before the baby leaves the hospital. That sets the tone for further testing. Some kids need to be followed very, very closely, and some kids, as I mentioned previously, might resolve or significantly downgrade their kidney dilation.
Melanie: After the baby is born, you do an ultrasound of the baby's bladder, kidneys, and then you kind of keep a watch on them. What could happen, Dr. Herndon? Could they reflex back up into the system? Could they sort of be toxic, a little bit?
Dr. Herndon: Well, the kids—and that's where this risk stratification comes into play—as a group, as a whole, pediatric urologists have tried to get away from using preventative antibiotics. It's developed this risk stratification [I have] to try and classify kids into groups that are at low risk of infection, and that's based on the degree of kidney dilation that we see prenatally. Kids who are at moderate risk and high risk, those kids, if they do have urine that backs up, which is one of the [ideologies], they're at high risk of having kidney infection and toxic, like you said. If they're at low risk of infection, even if they do have urine that backs up, they're probably not going to get infected, hence not become toxic. That's the tricky part is we don't study every child. If we did, we would pick up disease in kids that might not necessarily have an issue with it. They keep up with this disease. One of these conditions is reflux, where the urine backs up. Those kids are managed with long-term antibiotics. We're trying to get away from that.
The other ideology is kidney obstruction. But luckily, those kids predominantly have severe kidney dilation, grades three and four, so those kids, we kind of know based on that ultrasound. The kids that tend to get that trouble, we kind of have a lead on that, because of the severity of the kidney dilation in terms of the kidney blockage. Kids that have urine that back up to the system reflux, the ultrasound helps us classify the risk of infection, and that's what directs the intervention with the invasive testing to diagnose the urine that backs up to the kidney.
Melanie: For the most part, are they able to filter this out when you see? Of course, you can't study every baby, but are they able to filter this out? If they're not, is there surgery required? Are there other certain other interventions besides the long-term antibiotics?
Dr. Herndon: Sure. Going back to the ideologies, the most common is transient, meaning it does go away. That takes care of 70 percent. The urine that backs up the reflux, those kids typically do well that are picked up prenatally. If you look at that group, they get infected, but at a much lower rate than kids that present later in life with reflux and infections. Infections, when you're dealing with urine that backs up to the kidney, that drives surgical intervention, not necessarily the presence of urine backing up. Some of those kids will have surgery, probably about 20 percent because of infections, but a little bit depends on the severity of urine backing up. Kids that have the same volume that's in the bladder backing up to their kidneys, those kids are more likely to have surgery. Kids that have minimal urine backing up from bladder to the kidneys are less likely to have surgery. That group of refluxing patients, that's what we call that Vesicoureteral reflux. Those kids, they're a spectrum; most kids will not need surgery, but a subset will, and those are the same kids that are getting infected or have very high-grade reflux.
Melanie: Dr. Herndon, these babies in the prenatal NICU, are they, when they're born, they've got this condition?
Dr. Herndon: No. Most babies are not. Most babies are born on the regular ward, and a small subset will be delivered in the NICU, but that's very uncommon. Most of these babies are delivered at community hospitals, or they might be delivered at UVA. They have an ultrasound after the baby's born. Most of this work up is done as ambulatory, so in the clinic. They would come back and see me at one month, and we would repeat the ultrasound. If the patient is one of those moderate- to high-risk stratifications, then we would have the invasive testing, where we slip a little catheter in the bladder and use contrast to determine if urine backs up to the kidney, or if there's an abnormality with the urethra, the tube that leads from the bladder.
Melanie: Dr. Herndon, in the last 20 seconds or so, explain to the listeners why they should choose UVA Children's Hospital for care for this condition.
Dr. Herndon: One of the reasons is we offer a multi-specialty approach. I run a prenatal clinic with maternal-fetal specialist, Chris Chisolm and his group here at UVA. That gives us the opportunity to meet the families prenatally and to meet the mother and to explain to her what the risk stratification is for her baby. And then that allows one, for education; and two, for her to know what to expect postnatally.
Melanie: Thank you so much. You're listening to UVA Health System Radio. For more information, you can go to uvahealth.com. This is Melanie Cole. Thanks for listening.