2:02

So our objectives for this

2:06

session are to look at some real life cases and talk

2:09

about things that are frequently encountered.

2:11

We'll also discuss some rarities, but focus on the common,

2:15

and we're going to dip into embryology.

2:17

I know embryology is not always

2:18

everyone's favorite topic,

2:20

but it really helps a lot to understand what's

2:23

happening in the embryo and the fetus

2:25

in order to understand the genitourinary anomalies

2:29

that are frequently first identified in the

2:31

newborn period and even prenatally.

2:33

So antenatal hydronephrosis is the number

2:36

one indication for ultrasounds after birth.

2:41

And so, we will follow up on some of those embryology

2:46

questions and then I want to emphasize over and over.

2:49

During this lecture,

2:50

that urine is moving down a one-way street.

2:52

So almost all of our problems can be identified

2:55

when we see disruption of that one-way traffic of urine.

3:00

So moving along, we're going to look at cases

3:06

of antenatal hydronephrosis,

3:07

and we're going to look at some of those embryologic

3:10

anomalies and even some associated cases

3:13

that start out as ventral wall defects,

3:17

or failures of the ventral fold to close.

3:19

So this is a fetal MR image of a bladder outlet

3:23

obstruction, a lower urinary tract obstruction and you

3:26

can see this really expanded, bladder and posterior

3:31

urethra. This turned out to be a case

3:32

of posterior urethral valves,

3:34

but we're going to be looking at cases like that,

3:37

upper and lower areas of obstruction.

3:40

So just...

3:41

why is it important to be able

3:43

to identify these things early?

3:45

Well, it turns out that prenatal hydronephrosis

3:48

is something that's very common.

3:49

It's a very common cause of all prenatal abnormalities.

3:52

It's also a very common cause of,

3:55

you know,

3:56

the ultrasound imaging that we do after birth.

3:59

We can also with fetal MRI as well as prenatal

4:02

ultrasound, and there are cases now where

4:04

we're doing intrauterine intervention.

4:06

So if there's a bladder outlet obstruction,

4:07

for example,

4:08

you can place a shunt which will decompress some of

4:11

that fluid and there's been variable

4:13

success with that intervention.

4:15

There are also amnioinfusions. So if the fetus

4:18

doesn't void, then the amniotic fluid gets

4:21

swallowed and now there's no more amniotic fluid,

4:24

it's not coming back out and sometimes we can infuse a

4:28

supplemental amniotic fluid to help the fetus.

4:32

So, what we're going to be doing in most of these cases

4:35

prenatally is we're going to be looking at the dia-

4:38

the diameter of the renal pelvis. And these are some of

4:41

the numbers that people frequently cite as cut-offs.

4:45

And I as you can see, the number changes around

4:47

the thirty three week period. Interestingly,

4:50

the thirty three week period is also a really important

4:53

time in terms of whether the lungs are undergoing

4:57

net absorption of fluid or net secretion of fluid.

5:00

So we can see a lot of corollary

5:04

effects in the pulmonary,

5:05

the fetal pulmonary system with the urinary

5:09

abnormalities. And that ends up being a really

5:12

important determinant of outcomes.

5:14

So this is a two side-by-side images of

5:17

prenatal ultrasound. If you're disoriented,

5:20

you don't commonly look at these images,

5:22

always look for the shadowing from the fetal

5:24

spine and you can see the shadowing here

5:26

so you know where posterior is.

5:27

And then on either side of that spine, in the

5:30

retroperitoneum, of course,

5:31

are the fetal kidneys. And you can see measurements

5:34

taken of the renal pelvis here.

5:36

This is a fairly common thing to see a

5:38

little bit of fluid in the renal pelvis.

5:40

Sometimes our obstetrical colleagues will refer to

5:42

this as pyelectasis. Postnatally, we would say

5:46

pelviectasis. That's not a concerning finding.

5:49

Here, we can see a little more asymmetric dilatation.

5:52

This is kind of a traditional transverse or,

5:55

you know, we might say axial view,

5:57

where you can see that fluid in the renal pelvis

5:59

and in this more of a coronal view,

6:01

you can identify the splitting,

6:03

the bifurcation of the great vessel.

6:05

So that's too much fluid.

6:06

That's abnormal and asymmetric renal pelvic dilatation,

6:10

and that's something that's going to be followed up

6:12

after birth. Here's the corollary of the fetal MRI.

6:16

This is...

6:17

the maternal body is upright,

6:19

but the fetus is in cephalic presentation.

6:23

So that's why it's upside down. And you can see,

6:24

bilateral,

6:26

renal pelvic dilatation, but much more severe on

6:30

one side than the other. It can be

6:32

sometimes difficult to determine what side you're on.

6:34

But here's the stomach,

6:35

so we can be pretty confidence the left kidney.

6:38

We've got caliceal and pelvic dilatation there.

6:41

And then here's what it looks like on an axial

6:43

image of the fetal body on MRI. So here's the spine,

6:46

of course,

6:48

here's renal pelvic dilatation here,

6:50

some renal pelvic dilatation here,

6:52

and then this massively dilated ureter as well.

6:56

So we know there's some distal obstruction.