Topics in Perinatal Genitourinary System Evaluation - HD

Introduction to Fetal Genitourinary Tract Evaluation

Hi, this is Harris Cohen.

I'm chairman of radiology at University of Tennessee and radiologists in chief at Lab Bon Children's Hospital.

And we'll be talking about topics in fetal genital urinary tract evaluation.

We'll be discussing some topics in the perinatal assessment of the genital urinary system, predominantly looking at ultrasound, the fetal kidney, knowing the abnormal allows diagnosis of abnormality.

This is in a sense of philosophy for all areas of evaluation in radiology.

Normal Imaging of the Fetal Kidney

It's said that the fetal kidney is routinely imaged by 17 weeks.

It obviously can be seen earlier than that.

Certainly transvaginal ultrasound can see it earlier than that, but modern equipment using a transabdominal approach can do the same.

A number of years ago, they said that the fetal kidney was more easily seen in the third trimester, perhaps because of increased perren fat.

I don't believe that's necessarily true on transverse view.

There's a classic hypo coic mass on each side of the spine and soft tissues of the back that are noted.

Gran and early pioneer in ultrasound said that the kidney circumference over abdominal circumference ratio maintained a 0.3 or so ratio throughout fetal life.

Here's just an image of a kidney and a kidney on both sides of the vertebral column, which shadows toward the anterior portion of the fetus.

The posterior portion is seen posteriorly, which is superiorly on this image.

Fetal renal pyramids are found in anterior and posterior rose.

Distinguishing Renal Pyramids from Cysts

At one point in my life, a number of patients were being sent to me for fear that they had fetuses with cysts within their kidneys.

But if one sees these echoic areas and they're not purely echos areas and they're both in anterior and or posterior rose, one can state that their renal pyramids, their normal structures and the child does not have cystic kidney disease.

They are not cysts.

This is an example of pediatric renal pyramids found again similarly in anterior and posterior rows with arrows showing some superiorly within the image and some inferiorly within the image do not confuse them for cysts.

Fetal Kidney Size: Historical and Updated Measurements

So what is normal, at least with regard to fetal kidney size, what is considered normal has changed over time, with work from us helping this.

A couple of decades ago in 1983 and in the late 1980s, people were using lias fetal kidney measurements.

Essentially, they said that for a given week of gestational life, the mean length of the kidney was about the number of millimeters for weeks of gestational age, and there was a range and the two standard deviation range is seen in the third column.

So again, the accepted standard was about a millimeter per gestational age week.

We found that a number of patients were therefore considered having larger kidneys than normal, and because larger kidneys than normal are sometimes associated with cystic renal disease and infantile polycystic kidney disease or recessive, polycystic kidney disease may not have evidence cyst, but be seen as an echogenic kidney that sometimes families were made to fear that the child's kidneys were too large and they might have a terrible cystic disease of the kidneys.

So we ended up doing a study that was published in the A JR in 1991.

It noted that the greatest it was, it tried to evaluate the greatest length of 498 kidneys imaged in 398, consecutive 18 to 41 gestational age weak fetuses.

The reason why there are not that many cases in which we saw two kidneys in each patient was because we did not accept any kidney that was not seen readily in three planes.

We excluded anyone who was an abnormal fetus.

We excluded twins.

We excluded the offspring of a diabetic mother who might have a larger than normal kidney, and we excluded anyone with renal pelvic diameter measurements of greater than four millimeters despite the fact that up to 10 millimeters can be physiologic.

We didn't want to falsely enlarged renal length based upon dilation of the renal pelvis, despite the fact that it may be physiologic.

In this study, we found that mean mean length and ranges of kidneys were greater than once thought that there was no significant difference between the length of the right kidney or the left kidney, and that there was a strong correlation between renal length and gestational age.

There was, however, no correlation between parental height and weight and fetal kidney length or measurements the mean length.

And the ranges are noted on the table here and one can see that, for example, at 30 weeks, the mean length is much greater than 3.0.

It's 3.8 centimeters, and the range of normal is 2.9 to 4.6 centimeter, allowing for mean lengths, which were more than a millimeter per gestational age week.

In addition, the ranges of normal measurements were far greater than previously reported.

This just is a table of some of the measurements between 18 and 24 weeks.

This is a graph that shows dotted lines showing the mean and the two standard deviation of normal of Burton Nolis numbers, which we were using in the early to late 1980s compared to our measurements which show a mean that's much larger and two standard deviations greater than that mean even larger than that.

So again, our studies show that we're different means as well as different standard deviations for normal renal length.

When one says something that's quite different than what has been used in the literature, one has to prove it.

And we were fortunate that not only was there a Holloway study and a Rosenbaum study that showed measurements of full term neonates, but there was also a fit Simon study that showed the measurements of premature neonates.

Those measurements placed against our measurements and fetuses showed them to be similar and allowed us to know that our measurements were more correct than the measurements used in the past, past than the measurements used in the past, which is seen in the lower line.

Renal Agenesis and Ectopic Kidneys

The fetal kidney may not always be in the renal bed.

It's seen in the renal bed here, the right kidney and the left kidney.

If it is not seen, it may be because there's renal agenesis and the kidney is absent or the kidney may be in an ectopic location.

Knowing whether a kidney is absent or ectopic is important information Suggesting the fact that a kidney is not present in its location may be thought about.

If the adrenal shape is unusual, the adrenal tends to be v or y shaped.

But if it is linear as in the lying down adrenal sign, it's often in the indication that the kidney never rose from its embryologic position in the pelvis up to the area of the adrenal.

The adrenal is formed embryologically in a superior position, and the kidney normally rises as the meta nephros rises to meet the adrenal gland once you look for the kidney in either the pelvis.

And one may be fortunate if there's fluid in the bladder to evaluate this because if it's just collapsed small bowel in a given zone, one may not be able to see the kidney.

The kidney may be obscured and one should look if the kidney is not in normal position.

One of the ways of handling that is to look for the position of the renal arteries, whether it's aided by power doppler or color doppler.

This is just an example of adrenal glands in three normal fetuses.

This is a y shaped adrenal, which can look small.

Adrenals can also look big in relationship to the kidney, And this is just a coronal image of a triangular adrenal gland seen above the kidney.

The lying down adrenal gland again is a sign of renal agenesis or utopia Hoffman et al.

Discussed this in Journal of Ultrasound and medicine in 1992 stating that the shape of the adrenal gland is affected by its relationship to the ipsi lateral kidney.

With the kidney absent the adrenal no longer caps it but becomes flattened and on the left side appears to be lying down on the aorta.

This can be seen both in fetuses or neonates, although I have seen exceptions to the rule on both sides of the life barrier, meaning I've seen it in fetuses, I've seen it in neonates.

This is an example of a lying down adrenal gland.

This is the cruise of the diaphragm, but this is the adrenal gland and it is linear.

There's no kidney seen in that renal bed, and again, that's in relationship to this normal Y or V-shaped adrenal gland.

This is an example of a fetus in which the chest is seen at this site.

The bladder is seen at this site.

I mark off where the heart is and the left kidney seen over here is not in the renal bed, but rather is closer to the bladder.

So this would be renal utopia rather than renal agenesis.

This is a case in which kidney and kidney are seen on both sides of the vertebral column, the vertebral body.

It's possible that this could have been one fused kidney as in a horseshoe kidney, but this wasn't, and we saw a bowel between it, between the two areas of kidney proving that they, it was just bilateral ectopic kidneys.

So this is an example of a black and white image in which kidney is marked off.

And then another image in which color Doppler shows renal arteries extending horizontally.

They can sometimes be somewhat oblique from the aorta proving that there is kidney at the side if one could not see the kidney that well.

This is another example of a renal artery seen on the side where a kidney was noted, but a green arrow pointing to a side in which no kidney is seen in a patient with renal agenesis, And again, a normal aorta with its bifurcation here and with renal arteries extending on both sides of the aorta.

Another sign for utopia that I've seen is when one sees a prone fetus, as in this case, this is the vertebral body.

This is in a, this is a kidney in which rib is seen near it, but on the other side the kidney is seen here and there's a distance between the posterior aspect of the kidney and where one would see rib or paravertebral muscles.

When I see this where one is more anterior than the other, I have to rule addict topia, which was proven in this case.

Fetal Hydronephrosis and Ectasia

Fetal hydronephrosis and ectasis.

The goal for the examiner is to make an early diagnosis by imaging, by imaging renal pelvic diameter so that appropriate therapy can occur for cases of genital urinary system obstruction, either a UPJ ureter, pelvic junction obstruction, A-U-V-J-A ureter, ve a ureteral vesical junction obstruction or posterior urethral valves, or vesco ureteral reflux, which is the reflux of material from bladder up to the kidneys, which can lead to renal scarring, atrophy and destruction.

And it's good for this diagnosis to be made as early in life as possible.

Importance of Early Diagnosis

Why is an early diagnosis important?

Because obstructive nephropathy places future renal function at risk and in a very old study by major in pediatrics in 1975, looking at 10 year follow ups of reconstructive surgeries for significant obstructive nephropathy, they found that function improved or normalized only if the surgery occurred in the first year of life.

While if surgery was performed in the second year of life, that was progressive deterioration of function.

What exactly the current clinical thought is may be debated by clinicians, but certainly the earlier the treatment the better.

So again, fetal hydronephrosis and ectasis after 24 weeks gestational age, there may be some image dilation of the OC CAE system.

Again, a transverse image in which the pelvis is seen as somewhat dilated on both sides.

This being one kidney and this being the other kidney in the O-B-A-G-Y-N text by Berman Cohen, it was noted that 41% of normal fetuses have at least two millimeters of dilation and 18% of normal fetuses may have three to 11 millimeters of renal pelvic dilation.

Whether this is on the basis of maternal hormone stimulation or if it's on the basis of fetal bladder filling, similar to adults in which if a bladder is filled, it may press on the ureters and allow the renal pelvis to appear more dilated and that can be seen, for example, in late term pregnancy.

One is unsure, but we have done work that has shown that fetal bladder filling may affect dilation of the renal pelvis.

In 1986, Gral talked about 70 fetuses and 90 kidneys in which there was renal pelvic dilation.

There've been many articles since I like it because this article discusses the number of patients they had for each of a series of abnormalities causing renal pelvic dilation.

If there was an abnormality, 29 of their patients had UPJ obstructions.

Six of their patients had UVJ obstructions, four of their patients had posterior urethral valves.

Three patients had prune belly syndrome, which is really due to a mesodermal defect and dilation that may not be obstructive.

It isn't obstructive.

And then there is distal ureteral stenosis was, which was the diagnosis for two of their cases.

But you see that the vast majority of cases were normal.

45 of these 90 kidneys were normal despite the fact that there was renal pelvic dilation.

In their article, they talked about grading the various kidneys saying that grade one was up to 10 millimeters of dilation and stating that none of those patients ever went to surgery.

That grade two was 10 to 15 millimeters of dilation and 39% of their patients went to surgery for some reason or another.

Grade three patients, 62% went to surgery.

Those were those greater than 15 millimeters of dilation with slight dilatation of the caly disease.

But the group that one has to really fear are people with 15 greater than 15 millimeters of dilation, either with moderate or severe dilatation of the caly disease or with cortical atrophy.

And in their study, a hundred percent of those patients went to surgery, whatever the surgery may have been.

Grading Systems for Hydronephrosis

The Society for Fetal Urology in 1993 graded things according to what's seen on this chart, no dilation was grade zero and then they had grades 1, 2, 3, and four with the worst being grade four in which there was renal pelvic dilation, dilated caly and thin cortex.

This is just an example of a kidney with six millimeters of dilatation, another kidney with six millimeters of dilatation or dilation at 29 weeks gestational age, and this is probably physiologic, this is an example of renal pelvic dilation of 10 millimeters, which would be labeled grade two.

This is seen on the right side with nothing seen as dilated on the left side.

Peter Auger said a number of years ago that he would worry when the AP pelvis was greater than 50% of the AP measurement of the kidney.

So Grignon study their grade twos were those with one to 1.5 centimeters of AP pelvic diameter in normal CAEs.

Their grade threes we discussed, this is just an example of a grade four in which is a very dilated pelvis and at least moderate dilation of the CAEs.

And a hundred percent of this group in their study for many years ago went to surgery.

Measurements and Follow-Up for Abnormal Pelvic Dilation

Should one count the measurements for abnormal pelvic dilation.

The same throughout pregnancy has been a question answered by many, many, many different groups and studies of thousands of pregnancies.

But court fill as well as others say that one should not use the same number and that perhaps if the child is less than 20 weeks, one should follow with a lesser dilation.

In the case of Mandel in 1991, they followed five millimeter dilation at less than 20 weeks, an eight millimeter dilation at 20 weeks and beyond, and we've used a similar methodology.

Court fill said that there was a difference in sensitivity and false positive numbers based upon whether they called abnormal at four millimeters or abnormal at seven millimeters, and one can read the sensitivities and false positive numbers on this chart.

Langer as one of many, many articles on the subject.

In 1996 study 2,170 pregnancies, 89 of them, 4.4% had dilated renal pelvis.

They considered dilated renal pelvis, those greater than 10 millimeters on less, less than 28 weeks, and then they considered it abnormal at five millimeters.

And what was the result of all these cases of dilated pelvis?

They found 13.7% of them to have obstruction or significant vesco ureter reflux or a mega ureter.

30.5% of them had no obstruction, just pelvic dilation, but 55.8% had no abnormality.

And it's been shown in multiple studies that you may be dilated before delivery and then in neonatal life not be dilated.

But you could also as a fetus, not have dilatation and then have dilatation as a neonate.

The general rule is do not consider abnormality if dilation is less than 10 millimeters beyond 28 weeks gestational age, particularly if there's no associated bladder or ureteral dilation.

And if five to 10 millimeters of dilation is seen in the second trimester, they stated that they would repeat the exam in the third trimester.

One of the key things to know, however, is that when these children are born, this is not an emergency.

One has to evaluate immediately, but rather one should avoid the relative hypovolemia of the first 24 hours of life and know that a static exam may be harmful because it may underscore or underestimate dilation.

Best thing, according to our work is to perform an examination at 48 to 72 hours of age to assess what pelvic dilation is.

Different people have different opinions.

I would prefer the information be known during the time that the patient's in the hospital.

But if you have a patient that'll come back as an outpatient, then you can make a decision with your urologist.

Renal Duplication Anomalies

Renal duplication anomalies have a Wgar Meyer rule.

They can be seen in fetal life in them.

Typically there's an upper moiety and a lower moty with most typically the upper moty obstructing its ureter travels medially and inferiorly to that of the lower moty.

Its ureter has an ectopic entry, whether in bladder or another place, often associated with the ureteral, which is cystic dilation of the submucosal segment of the intravesical ureter.

The lower ity often refluxes.

So this is an example of a longitudinal image of a kidney.

Lower pole of the kidney is seen here.

There is dilation of the renal pelvis with some caleal dilatation due to reflux, but the larger cystic area in the upper portion of the kidney is the obstructed upper poly moiety.

If a VCU was performed, one might see filling of a ureter and filling of lyes, but not a complete group of CAEs.

So we're missing some CAEs in the superior portion of this kidney because that portion is obstructed and we're only filling the lower moiety.

And this has often been likened to a drooping lily.

So the classic VCU image of a duplication anomaly is seen to your left and a drooping lily is due to filling of only the reflux portion, the lower moty of the kidney.

This is an example of another patient superior seen to your left inferior is seen to your right.

Ureter is dilated, the pelvis is dilated, the caly are dilated, but it's not the complete kidney because a portion of it extends to the upper moty, which in this case very unusually was echogenic due to dysplastic parenchyma.

This is a transverse view of a bladder in which you see a ure seal on the left and a ureter seal on the right, Despite the fact that urac seals may be extra vesicular, which they can be.

One should call it only after proving that it's not just a dilated distal ureter, which tends to look tubular in shape.

And this is just an example of a tubular dilated ureter and not a urease seal.

Bladder Evaluation

The bladder, its presence suggests that there's at least one functioning kidney.

Some fetal urine production begins at week 12, but it's not significant until weeks 18 to 20.

People have talked about keratinization of the skin at some point preventing amniotic fluid volume and composition from being modified except by swallowing and urination.

This is an example of a bladder. Stomach is seen here.

These are the ribs and the chest, I'm pointing to the bladder.

And if one looks at the umbilical vessels, one can follow them as they enter the pelvis and surround either side of the bladder.

And this is a bladder. This happened to be a unique case in which there was also dilation of a structure superior to the bladder.

This is a coronal image and that was because there was obstruction and that was filling of the UCUs.

Bladder dilation has been suggested as a cause of renal pelvic dilation.

A thick bladder wall when the bladder is filled suggests obstruction if it's underfilled thickness doesn't indicate abnormality.

Early bladder obstruction has been linked least in sheep experiments to the cause for cystic renal dysplasia.

This is a coronal image of a bladder who, which is thick walled.

The bladder looks a little less round than usual and more tubular and longer differential considerations include posterior urethral valves with their redundant membrane as falls leading to a dilated posterior urethral.

Vesco Ureteral reflux which can occur with valves or other reasons, may lead to fore rupture within the kidney and the visualization of urinary ascites, which in most instances will be e eChoice.

Urethral atresia can cause bladder outlet obstruction, but it's less common than posterior urethral valves.

And cordal regression syndrome is a rare abnormality of variable severity, which also involves the sacrum, the gastrointestinal, as well as the genital urinary tract.

All of these and anything that causes decreased amniotic fluid can result in potter syndrome and Potter fas, this is a prone fetus.

The fetus has renal pelvic dilation bilaterally, but in extending inferiorly toward the bladder, one was able to see dilated tortuous ureters.

In my opinion, tortuous ureters indicate long-term problems, either long-term reflux or long-term obstruction.

In that case, we were able to follow the patient to a distended bladder.

I show this average image in particular because there's an echogenic structure here and that echogenic structure was in the posterior urethra, which we believe was valve tissue and improved to be a case of posterior urethral valves.

Dilated in thick wall bladder here seen in a neonate can sometimes be further evaluated by taking the transducer, pointing it inferiorly and one may see a dilated urethra as well as the dilated bladder.

This is a VCU that shows a classic post urethral valve study, a Christmas tree type of thick wall bladder with a very dilated posterior urethra and radiolucency within the contrast from this VCU representing valve tissue.

We have shown both in that last case in which we showed a fetal valve, but we've also been able using a trans peroneal approach and neonates be able to see valve tissue in a dilated posterior urethra.

So this is dilated posterior urethra and this is valve tissue.

We wrote this up in radiology in 1994 and we'll one can see an image that we have a drawing of using an older transducer showing thick wall bladder.

Here you can see the bladder wall thickness here and posterior urethra that was dilated in a patient with posterior urethral valves.

Cystic Renal Diseases

As a change in topic, cystic renal disease has a potter classification that some people do not like because it mixes up genetic disease with other disease.

But historically, type one disease is recessive or formerly known as infantile polycystic kidney disease.

Type two is multicystic dysplastic kidney.

Type three is dominant polycystic kidney.

And type four is cystic renal dysplasia thought due to any early urinary tract obstruction.

Again, many dislike the classification 'cause it mixes up genetic disorders with dysplastic disorders.

There are some new concepts of renal cystic disease.

A acne and 2010 discusses genetic mutations and ciliary diseases as the cause Problems of primary clia as the origin of many renal cystic diseases as well as associated HEPA orreal fibrocystic diseases are discussed by them in that article.

Which one could look at primary C microtubules cellular organelles extending from the renal epithelium.

Primary C rich in receptors ion channels signaling, ProLon signaling proteins, proteins involved in regulation of cell proliferation and differentiation in developing a mature kidneys.

Defects and structure and function of primary CLIA are thought to lead to various cystic renal phenotypes and there are a whole group of diseases one could see on this list.

Despite the causes, fetal kidney abnormalities can be searched for by morphologic findings.

Five key points are there are needed to be assessed.

Five key points should be assessed renal echogenicity, comparing it to liver and spleen, renal length and size, cortico medullary differentiation cyst, the number of cyst, the size of cyst, location of cysts and amniotic fluid level or can the child produce adequate amniotic fluid.

Important points to know are family history.

This is an example of a transverse image of the abdomen in which the entire abdomen is filled with these two echogenic, somewhat heterogeneous structures which were due to cystic renal disease and a patient with recessive infantile polycystic kidney disease, recessive, infantile, polycystic kidney disease.

This is another example of very large kidneys in which you see no individual cysts.

This is someone who had recessive polycystic kidney disease and this is an R showing again how large the kidneys are and how much they represent the contents of the upper abdomen.

This is an example of multicystic plastic kidney in which the largest cyst is not the central cyst as one would see in hydro nephrosis, but rather there are multiple cysts of variable sizes.

The kidneys can be larger than normal, smaller than normal or normal.

There's usually adequate amniotic fluid because this is usually a unilateral disease.

It can be bilateral, but that is not compatible with life.

And this is again, multicystic dysplastic kidney largest cyst, again, is not the central cyst.

Atypical hydro nephrotic form does exist.

Most will wane in size over time, so after the child's born they will disappear, but up to 50% of cases have contralateral abnormalities, which can represent reflux or UPJ obstruction.

This is a neonate with several cysts of various sizes and an area of abnormal parenchyma indicating multicystic plastic kidney Work by glaze Brooke in 93 on 29 unilateral MCDK patients and their contralateral kidney and four unilateral re renal agenesis patients and 27 age match controls indicated that 92% of controls had a contralateral kidney of the fifth to 95th percentile, but 84% of abnormals had a solitary kidney greater than 50% greater than the 50th percentile, and 36% of abnormals had their solitary kidney or their solitary normal kidney at greater than 95th percentile.

This information indicates that there is compensatory renal growth even in prenatal life.

We know about it in the young who when losing a kidney, the other kidney will compensate.

This article proved prenatal compensatory renal growth.

Testicular Abnormalities

This is another fetus. This is a scrotum.

It was diagnosed as having bilateral hydro seals.

There is some hydros eal here, but this testicle looks abnormal.

This testicle looks abnormal and there was something tremendously wrong.

So I'm showing you a, a normal two normal testes and a large hydros seal.

That's what a hydros seal looks like.

There's a smaller hydro seal on the opposite side.

They're usually ecos and the testes is homogeneous.

In this case, there's a white central area consistent with the mediastinum testes, but in the case of the abnormal images I just showed you, they weren't bilateral hydros seals.

There was a partially infarcted teal on one side and another testicle that became much smaller than normal after infarction.

Along with small hydros seals, testicular torsion, the extra vaginal type in particular can occur in fetal life.

The cord is poorly fixed in the inguinal canal.

Torsion of the cord occurs outside the tunica.

Often it occurs in utero and it can occur in newborn, although I've mostly seen it in in utero cases.

There's a red swollen scrotum after the child's born and it's firm and painless.

This is an example of a neonate born with what is an echoic testicle with an echogenic border and a not as abnormal looking testicle on the opposite side, but both of them were painless to urologist pressure and for example, the one with that was echoic centrally with an echogenic rind had torsion and the one that looked more normal had torsion probably of a less lesser age.

Testes sometimes are a little more difficult to evaluate if there's limited scrotal size, but if one keeps attention to getting adequate scrotal imaging, one will.

Summary of Key Topics

So we've discussed several topics in fetal genital urinary analysis.

We know that fetal kidneys are bigger than once thought, and they can be normal in length, yet greater than one millimeter per week of gestational age.

We learned that the adrenal shape may indicate renal utopia, but indicated to be where the adrenal shape may indicate renal utopia.

Beware of the lying down adrenal sign.

A linear adrenal AP measurements of a dilated fetal renal pelvis and caly c may help predict chances for postnatal surgery, especially if the dilation is greater than 15 millimeters.

Predictions for smaller measurements, particularly those less than 10 millimeters dilated when we're talking about renal pelvis are more limited.

They can certainly be normal, one may have reflux and yet have normal fetal renal pelvis, images and measurements.

Ultrasound may allow the actual imaging of a posterior urethral valve and a transperineal approach may aid, which is placing a transducer between scrotum and anus.

It can be seen in neonatal life and it can be seen in fetal life.

Multicystic dysplastic kidney is a unilateral abnormality in those who have it and survive.

Testicular torsion can occur in fetuses and neonates.

Central vascular flow suggests just like with teenagers, salvageability, the end.