Fetal GI and GU Anomalies - HD

Introduction to Fetal GI and GU Anomalies in Pregnancy

My name is Dr. Roya Sohi and today we're gonna talk about fetal GI and GU anomalies in pregnancy.

First I'm gonna go over some of the standard views through the abdomen and pelvis and then talk about some GI scenarios and GU cases.

Standard Views in the Abdomen and Pelvis

One of the most important measurements that we take in pregnancy is the abdominal circumference. It is the most heavily weighted measurement for predicting fetal weight. And the AC image is also an opportunity to look at the stomach.

So the AC should be round, the stomach should be reliably seen after 14 weeks as a fluid filled structure on the left side of the abdomen. And if you take side by side axial views of the four chamber heart and the AC and note the fetal position or what side is up and what side is down, you can show a nice normal situs relationship.

Another standard view is visualizing the diaphragm. The diaphragm is a hypoechoic muscle. We don't wanna confuse it with ascites and we wanna show that it is intact from front to back and really from side to side. It is yet another chance to look at situs and to look for cardiac shift. And therefore it is recommended as part of the detailed exam of the fetus.

Having said that, it's just worth knowing that it's really difficult to evaluate the full diaphragm and when there is really a question about it, MRI is probably better in showing the diaphragm.

The abdominal cord insertion site is yet another standard view we want to see. It's an axial view showing the cord coming in an intact skin on both sides of the umbilical cord insertion site. We would wanna use the sagittal view when necessary if there's any concern about something being wrong at this site. And remember, physiologic gut herniation is normal before 12 weeks.

So at the cord insertion site in a 10 week embryo or fetus, early fetus, we can see that there is herniation of bowel at the base of the cord. And that is a normal finding.

Gastrointestinal Scenarios

So now that we've looked at some of the routine views, what about some GI scenarios where something might be wrong? We'll start with the example of an abnormality in which the stomach is large.

Now this could be a transient finding and the fluid is usually normal in the cases where the stomach is large, but then on close follow up of stomach is normal. However, having a large stomach could imply that there is obstruction and it could be obstruction from any cause. Duodenal obstruction is the most common reason that the stomach would be large. Gastric obstruction is actually rare. And then second most common would be jejunal or proximal ileal obstruction. In all the scenarios, polyhydramnios may be a later finding.

So first thing that once we catches our eye is the fact that the stomach is larger than expected at the mid gestation. So in this case, initially the stomach looks large at 25 weeks we have a fluid filled gastric fundus and a second fluid filled structure. And when we turn, we can get these two areas to connect. So we have a dilated duodenum dilated stomach. So this is of course duodenal atresia.

Duodenal Atresia

Duodenal atresia occurs because of a lack of normal duodenal canalization, which can lead to partial or complete obstruction. So when it's partial, it may be duodenal web or stenosis or complete would be a true atresia.

The ultrasound findings is that there's persistent fluid in the duodenum, which is always an abnormal finding. And by getting oblique images you can show the connection to the stomach. One can often in real time see hyper peristalsis of the stomach or you can see these folds on two dimensional imaging as well. Polyhydramnios is a later finding.

It's important to remember that a third of fetuses with duodenal atresia will have a chromosome problem most commonly trisomy 21 and about half to 70% will have other anomalies, often cardiac and other GI abnormalities. So these patients, once a diagnosis is made, behoove to have some genetic counseling and very careful look at the rest of the fetus.

And remember the duodenal obstruction is not always atresia. It could be from a duodenal web stenosis, annular pancreas malrotation with secondary obstruction from Ladd bands.

This is a case where 3D multiplanar imaging shows a dilated stomach and duodenum. This is our coronal views on follow up. The duodenum was even more dilated than the stomach. And at surgery after the baby was born, there was an annular pancreas that was causing the duodenal obstruction.

Here's another case that presented initially with a large stomach on follow up the stomach. The duodenum was also dilated and some proximal small bowel was seen that also was dilated and a very astute sonographer. And sonologist noticed in this case that the superior mesenteric vein was on the left and the superior mesenteric artery was on the right and there appeared to be this twist of the vascularity. So the diagnosis was made of malrotation with volvulus in this case. And the key to the diagnosis was the swirled mesentery and the SMV to the left of the SMA.

So remember that normal mesentery lies just so, but if there's malrotation, the cecum is pulled medially and you may have these fibrous bands called Ladd bands that can cause duodenal distension. And then if there's further volvulus, one can get obstruction of several different GI structures.

Jejunal and Ileal Atresia

Okay, let's move on to other atresias jejunal ileal atresia dilated bowels defined by bowel that measures more than seven millimeters. Sometimes the first clue that there may be an atresia is echogenic bowel. And we're gonna talk about that a little bit later.

With jejunal atresia we might see what's called the triple bubble sign. And remember, duodenal atresia gives you the double bubble sign. Again, polyhydramnios is more likely if the small bowel atresia is proximal, but it's usually not seen before 26 weeks. These cases are at risk for perforation and they have associations, like I said, malrotation, cystic fibrosis syndromes and meconium ileus.

Even without cystic fibrosis there's different surgical classifications of atresia, but in reality we can't tell the difference between these different types of atresias. I just show this to make it clear that it can be quite complicated.

So here's an example of a case of proximal jejunal atresia. Initially there are three fluid filled structures. This is the triple bubble sign, but with some oblique imaging we see that this part is the stomach hooks up to the duodenum, swings around to the jejunum. After the baby is born, you can see a dilated stomach connecting to a very dilated jejunum. Surgical specimen shows atresia very dilated jejunum.

Here, in addition, dilated bowel from atresia is at risk for perforation. So here's a case of multiple loops of dilated bowels seen by ultrasound and by fetal MR. But there's this additional fluid collection that looks different. There was no peristalsis seen in here. It has this thick echogenic wall, it has a different signal intensity on T two weighted MR from the fluid in the small bowel. And after the baby was born, this was shown to be a pseudocyst. So we could see rim like calcification on the x-ray of the newborn. And ultrasound shows this echogenic calcified wall and fluid within. So pseudocyst and ascites is a complication of these atresias.

Echogenic Bowel

Another scenario is echogenic bowel. And the key facts are that to make the diagnosis of echogenic bowel, we wanna make sure that we watch our technique. We wanna use the standard transabdominal probes and not the high resolution probes because those probes make all bowel look echogenic. The bowel should be as echogenic or more echogenic than adjacent bone. And focal echogenic bowel is more worrisome than diffuse.

Most commonly this is a very prevalent finding and most commonly the fetus is normal. However, there are associations with Trisomy 21 cystic fibrosis infection, meconium peritonitis, which I think of as a mimic. It has a different pattern. Fetal growth restriction is an association as is bowel ischemia, including situations that are complications of twin twin transfusion and bowel atresia.

Here's a case of focal echogenic bowel. You could see that at least part of this echogenicity is as bright as bone, but this fetus also had increased nuchal fold and the cardiac defect we could see AV canal and VSD as part of the AV canals. And of course this fetus has trisomy 21.

Here's a case of echogenic bowel, but in addition there's ascites, there's increased nuchal fold, which in this case was because of edema. So the baby has hydrops and increased peak systolic velocity in the middle cerebral artery. And this baby has parvovirus.

Here's a case of meconium peritonitis and we notice that there are echogenicities in the abdomen. They tend to be more linear and plaque like and surrounding the bowel. However, this is often put into the same category of echogenic bowel and the same workup is performed.

Small or Absent Stomach

Shifting gears, I'm now going to talk about the scenario of a small or absent stomach. So we talked about bowel dilatation, but what about when the stomach is small or absent? A fluid filled stomach should be consistently seen after 14 weeks. If it's not seen, it's worth getting one short term follow up after which one should really start talking about a differential of this finding and do further testing.

Differential diagnosis for the true small or absent stomach includes esophageal atresia, neurologic abnormalities leading to abnormal swallowing MSK abnormality leading to abnormal musculature and the abnormal location of a stomach. For example, if you can't see a stomach in the abdomen, perhaps it's in the chest in a case of diaphragmatic hernia.

So here's a case in which the stomach was exceedingly small even at 24 weeks the patient had the fetus, had polyhydramnios. So we go on and look up in the neck and here we see a nice fluid-filled normal airway. In addition, however, there is a fluid-filled pouch in the neck, which is this extending slightly beneath the level of the clavicles. So this is a diagnosis of esophageal atresia and this baby did have a TE fistula. We could see the feeding tube after the baby is born is in the esophageal pouch.

MR can be helpful. This is another case where nice fluid filled airway. This is filling of the piriform sinus and the trachea is seen here. And this is the airway. You could see the MR showing this in the same case, a nice fluid filled airway. However, in addition, this is an esophageal pouch leading into the upper chest. Here you can see the esophageal pouch and it's important not to call the normal airway the esophageal pouch.

So there's different types of esophageal atresia. By far the most common is type C where there is also a TE fistula, which means the stomach may be small in these cases or even normal because fluid is getting from the trachea into the stomach. The pouch sign, pouch sign may or may not be seen. Polyhydramnios is uncommon at 20 weeks. But a small stomach is not uncommon in these cases at 20 weeks, growth restriction happens in about 40% of the cases. More than half will have other anomalies, most commonly cardiac anomaly. And in particular tetralogy of Fallot, the associations include VACTERL and aneuploidy in five to 44%.

So genetic counseling is recommended for cases in which a small stomach is seen.

Abdominal Wall Defects

Okay, shifting gears once again, we are now gonna talk about abdominal wall defects. The common types are gastroschisis and omphalocele and less common include pentalogy of Cantrell body stalk anomaly and exstrophy especially in the GU system.

So suffice it to say that the embryology of bowel is difficult. The small bowel herniates into the base of the cord and turns and comes back in and turns again as the abdominal cavity makes room for bowel. Which raises the question, can an early diagnosis of abdominal wall defect be made? And I would argue that it can, if one remembers three key points. Number one point is that the bowel has to be back in the abdomen by 12 weeks. Number two is that the liver is never out. And number three is that the cord insertion can be seen and can be evaluated in the first trimester.

So using the cord insertion site, maybe we can make some of these diagnoses early. Here's an example of a low risk patient who comes in for nuchal translucency imaging at 12 weeks, three days. And we notice that there is a significant amount of extra corporeal bowel. The cord insertion is normal and the bowel herniation is to the right. So this is a case of gastroschisis which can be made with confidence at 12 weeks, three days.

Here is a case of an abdominal wall defect at 11 weeks, three days. But we notice that there is this bulge at the base of the cord and it contains liver. This is hypoechoic and actually with color doppler not shown here, we saw hepatic veins in this structure. So the liver should never be out. So this is a case of omphalocele with liver. You can actually see a little bit of the echogenic bowel also involved in the omphalocele.

Gastroschisis

So let's talk about gastroschisis. This is a full thickness right paramedian abdominal wall defect. There are really two types. Most cases are simple gastroschisis, meaning all that. The only anomaly is the extra corporeal bowel. No additional anomalies, no significant bowel dilatation and survival in these cases is near a hundred percent complex. Gastroschisis occurs when there's other organs that are also outside of the abdomen such as the liver or there are other anomalies in addition to the gastroschisis. In addition, if there is significant bowel dilatation, then that is considered a complex gastroschisis.

Intra corporeal bowel dilatation is more highly associated with bowel pathology than extra corporeal. And any bowel that's dilated more than 14 millimeters is associated with atresia thick echogenic. Matted bowel also has a worse prognosis.

So complications of gastroschisis include growth restriction, fetal death, bowel, atresia, short gut syndrome. The good news is it is not associated with aneuploidy. It is associated with younger moms. And the mean age is approximately 25 years old.

So here are some cases of complex gastroschisis now, whereas transient stomach and bladder involvement in the gastroschisis is typical in the third trimester. These exemplified two cases in which that it was, it's not normal to have the stomach out and distended consistently as we see in this ultrasound where the stomach is out and there's more dilated bowel. And in this newborn where the stomach is out and distended, same for the bladder. The bladder might be seen in and out. But in this case the bladder was consistently out and the fetus had hydronephrosis. These are considered complex cases.

Here's a case of complex gastroschisis because of intra corporeal bowel dilatation, you notice there's extra corporeal bowel decompression. And here's a case showing the extra corporeal matted bowel with a pseudo membrane. And this is because of a fibrotic membrane that forms because of exposure to amniotic fluid. And these both of these scenarios are more highly associated with bowel pathology.

Here's a case of complex gastroschisis sent as an omphalocele, however, we see that there is no covering membrane and the cord insertion is although it's to the side, of the abdominal wall defect, it, it is inserting normally into the abdominal wall. However, we do see there's this extra corporeal small bowel, stomach and liver in this case 3D ultrasound shows the extra corporeal liver, stomach, and small bowel as does MRI. MRI in addition, showed a clubfoot. And this is the gross specimen of the child who died in utero. And we could see that there's this extra corporeal liver, stomach and small bowel matching the 3D image beautifully.

Omphalocele

Okay, moving on to the second most common abdominal wall defect. Omphalocele, the key facts are that this is a membrane covered midline abdominal wall defect and the membrane is amnion and peritoneum. The umbilical cord inserts on the membrane not always centrally but still on the membrane. Liver plus small bowel involvement is the most common. So we see liver, small bowel on this diagram and on this MRI ascites is common. We could see a small amount of ascites in this case the bowel only on omphalocele, they can be smaller. However, interestingly, they are more likely to have aneuploidy than the larger ones with liver. Aneuploidy is seen in 30 to 40% of cases including trisomy 18. Trisomy 13. In addition omphaloceles are associated with several syndromes and other associated defects survival is 80 to 90%. If the finding is isolated, it's not unusual to see cystic membrane change. Remember the membrane is both amnion and peritoneum and often cysts occur between the two. It's also not unusual to have umbilical cord cysts when there is an omphalocele because of degeneration of Wharton's jelly on omphalocele plus other anomalies carry a worse prognosis.

Here's a case in which the right lobe of the liver is out. The left lobe is in the chest. The stomach is in the chest and this baby therefore has pentalogy and left-sided CDH. The prognosis is much worse for cases like this.

Here's a case in which there is an omphalocele. So the liver is extra corporeal here, but the baby also has a large, spina bifida defect and in addition had bladder exstrophy and imperforate anus. So this fetus has OEIS association.

Another case of omphalocele and AVSD and a case where there was an omphalocele. Here's the liver, but the tip of the heart was also out and there was a sternal defect. And so this is a case of pentalogy of Cantrell that survived because the significant amount of the heart was inside the chest. But it is important to notice this extra corporeal liver at the time of ultrasound ascites is common. I'm showing you a couple cases of a large amount of ascites in this case on fetal MR where we could see the extra corporeal and intra corporeal ascites. One has to look for other signs of hydrops, but this was pure ascites. And here's a case of a newborn that did quite well but had a large amount of ascites. And notice the eccentric cord insertion ruptured omphalocele membrane is exceedingly rare. And here's an example of when you can think of the diagnosis 'cause this baby had a lot of ascites, but then on follow up there was no ascites. However that doesn't, the, the prognosis is still guarded because that means there's no longer a covered, membrane protecting the liver in this case.

Genitourinary Cases

Okay, so now we're going to leave the world of gastrointestinal cases and move into GU cases. A brief review of the UTD classification system is in order.

It's, I think it's important to remember the numbers for hydronephrosis. Basically if the AP diameter of the renal pelvis is four millimeters or more, then one has to worry about hydronephrosis between 16 weeks and 27 weeks, six days. So the normal number is less than four millimeters for this gestational age. After 28 weeks, the normal renal pelvis measures less than seven millimeters and after babies are born, the normal renal pelvis measures less than 10 millimeters.

There are six other ultrasound features we want to look at. We want to look at calyceal dilatation beyond the central. And in a normal case, there's no peripheral calyceal distension, parenchymal thickness, parenchymal appearance, appearance of the ureter, the bladder and amniotic fluid should also be noticed in evaluating the GU tract.

So patients are placed into UTD A1 low risk category. If there's only mild renal pelvis distension, which is between four and seven millimeters, between 16 and 27 weeks, six days and between seven and 10 millimeters, between 28 weeks in term those are UTD A1 and everything else otherwise looks normal with those fetuses. If that is seen early, you wanna get a prenatal ultrasound at 32 weeks to see if it has progressed. And then after the baby's born, two additional ultrasounds are performed around two to three days of age up to one month and then around six months of age. And remember that mild renal pelvis distension can be associated with aneuploidy, but rarely does a low risk patient become high risk because of this finding.

All the other cases need more follow up and further workup after the babies are born. And there should be consideration of consultation with nephrology or urology while the patient is still pregnant.

So here are some examples. Here's a case example of a patient with UTD A1 meaning just renal pelvis distension and nothing else wrong with the kidneys and mom is low risk. So the next time we wanna see this patient is at 32 weeks. And in this case there is marked distension of the right renal pelvis and we could see peripheral calyceal distension. So further follow up was performed and every time this fetus was seen and then the newborn was seen, the renal pelvis became larger and larger as did the peripheral calyceal distension. So this is an example of UPJ obstruction.

UPJ Obstruction

Obstruction at the UPJ is the most common cause of obstructive hydronephrosis. 20% of all hydronephrotic cases are because of UPJ obstruction. It affects males more often than females. It's not associated with aneuploidy or genetic syndrome. So making an accurate diagnosis is helpful because we know that it, there's no association imaging pearls are that the renal pelvis and calyces are the only things that are dilated. The pelvis gets rather large can extend into the pelvis. The renal pelvis can extend into the fetal pelvis and can end abruptly in a bullet shape. That's one of the classic morphologic findings. Partial obstruction is more common than complete. 10% are bilateral and a quarter may have a contralateral anomaly.

Here's an example of two cases with severe UPJ and a complication that I think we need to talk about. So in this case, in mid gestation you could see bilateral renal pelvis distension and on follow up there's still pelvis distension and peripheral distension on the right side. On the left side there's decompression and fluid around the kidney. Here's another case with pretty significant early renal pelvis and calyceal distension early hydronephrosis. On follow up, there is a unilocular fluid collection in the flank and notice it doesn't have the bullet shape. It is simply an extrarenal fluid collection pushing the kidney medially as was seen with fetal MRI. So both of these fetuses have developed urinoma secondary to obstruction.

Urinoma is often misdiagnosed. You wanna consider the diagnosis when a fluid collection is seen that touches the lateral lumbar spine, especially if previously in that same case you have seen hydronephrosis on that side. So here's another case of a large urinoma and the kidney, the left kidney has been pushed medially. The prior theory was that if there's hydronephrosis and then the urinoma occurs that possibly that's protective because maybe the kidney has decompressed. But recent studies have shown that that's not true at all and most of these kidneys do not work well. And the, what the urinoma is telling you is that it was proof of pretty severe obstruction as in this case after this baby was born, you can see the urinoma lateral to this otherwise echogenic obstructed kidney and on the renal scan this kidney does not work at all.

Duplicated Collecting System

Okay, here's a new diagnosis. This patient comes in with a diagnosis of hydronephrosis and we notice that on the right side in the upper pole of the kidney, there's these cystic structures that did connect. So this is hydronephrosis of the upper pole. However, there's a significant amount of normal kidney present that we can see in the lower moiety. In addition, in the bladder there's this fluid filled structure right there. So what is going on here is that this is a duplicated kidney with ureterocele. After the baby's born VCUG was performed and we see the filling defect from the ureterocele. In addition, there is reflux into the lower pole moiety causing what's been called the drooping lily sign because it's being pushed down by that obstructed upper pole moiety.

So we wanna remember that with renal duplication. There is upper pole hydronephrosis because of ectopic and obstructed ureteral and lower pole reflux, which in utero often does not show up as hydronephrosis. And this is the Weigert Meyer rule of renal duplication.

Posterior Urethral Valves

Okay, let's look at another case in which the fetus is presenting with bilateral significant renal pelvis distension. There's hydronephrosis bilaterally and we look at the, the, morphology of the bladder. The fluid is low in this case and you notice that the bladder has a dilated posterior urethra and is thick walled consistent with posterior urethral valves as a cause for bilateral hydronephrosis. Follow up three weeks later in this case, once again you can see the bladder wall trabeculation dilated posterior urethra, markedly obstructed kidney on the right. And look at the kidney on the left, it is surrounded by fluid because again this case has developed a urinoma.

So what do we wanna know about lower urinary tract obstruction? Posterior urethral valves are the most common cause You have a variable amount of renal findings. The key feature is the dilated thick walled bladder. And you may or may not see a dilated posterior urethra. It may look like a keyhole. That's the classic finding. But it could look like a funnel or you may not really see it. There is a variable amount of amniotic fluid abnormality. There's two main concerns for these cases. One is renal injury. About a third of these patients will have end stage renal disease, need dialysis and transplant. However, the most single important prognosticator is the presence or absence of pulmonary hypoplasia. And this leads to about 45 to 55% mortality and then has to do with the compressive force of lack of amniotic fluid on the chest and the lack of growth of the lungs.

So the question comes, should we bypass the urethra? And there you potentially could put in a shunt if the kidneys are working to help alleviate some of the risk for pulmonary hypoplasia.

Here is a case that shows that not all dilated bladders are posterior urethral valves. So we see a markedly distended bladder. But notice it is not thick wall markedly distended renal, ureters and renal pelvis. And after this bladder was tapped, we noticed a redundant abdominal wall and there was the fluid leaked from the bladder around the fetus as well, even without putting a shunt in. So this is a case of prune belly syndrome prune belly syndrome has three components to the diagnosis. One is dramatic collecting system distension. Number two is deficiency of abdominal musculature, which may be difficult to see in utero. And number three is cryptorchidism findings will overlap with posterior urethral valves. You're less likely to have a keyhole sign. You the ureter might be dilated all the way to the tip of the penis. And we can look for that. The, not the ureter, I'm sorry, the urethra. The ureter is more likely to be overly dilated as well. Oligohydramnios is common but may not be as severe as with PUV. And then the small chest and pulmonary hypoplasia is also an issue.

Here are three different cases with prune belly and we can see the dilated urethra all the way through the shaft and then markedly dilated in this case. So this essentially rules out posterior urethral valve. And you can also see in the third trimester cases there is cryptorchidism. Here's a baby with prune belly and you can see that appearance, the classic appearance of the abdomen as well as the cryptorchidism. And then when the VCUG is done, this is a markedly dilated ureter.

So prune belly is more rare than PUV. It affects males much, much, much more commonly than females. It's associated with aneuploidy and other genetic defects and has similar neonatal issues of pulmonary hypoplasia and renal dysfunction and additional, problems with GI malrotation and anal rectal anomalies.

Cloaca

Here's a case that was sent to us as referral for bladder outlet obstruction, but this was not a classic bladder outlet obstruction at all. First of all, one of the most important differentiating factors is that this was a female fetus. Here's the fluid filled structure that was initially thought to be a bladder, but we know we noticed these wall, linear echogenicity. And in addition, when scanning this baby for a while, we noticed that there was a separate fluid filled collection which appeared to be the bladder. So this is not the bladder at all. This is a fluid filled large structure. In the middle of the pelvis, the kidneys were abnormal. There was post obstructive cystic dysplasia of one kidney and significant hydronephrosis of the other kidney. There was a two vessel cord. And when we looked in the perineum, we did not notice a rectum. We only noticed one perineal opening. She had an MRI. And interestingly on the MR, we couldn't see the separate fluid-filled bladder, but the morphology of the pelvic structure was very reminiscent of a very dilated vagina. And what we see here is the, fundus of the uterus also filled with fluid. Here are the kidney findings and the perineum showing labia, but otherwise, no orifice here.

So this is a diagnosis of cloaca. Cloaca occurs because of a failure of early cloacal division and there's a spectrum of abnormal anatomy which is related to the time of arrest. The classic cloaca is a coalescence of the urethra, the vagina, and the hind gut. And the structure that gets the most dilated in this case is the vagina because it has more capacity. So that is what we see with ultrasound. And to make things even more complicated, 60% of the time there will be duplication of the vagina and possibly duplication of the uterus. So these, this midline fluid filled structure can look quite odd.

So lining up the imaging again in our case, because cloaca is often misdiagnosed as dilated cyst or dilated bladder. It's worth taking another few minutes to look at the anatomy here. So large fluid filled structure. This was bladder. This was urine in the vagina. This is urine in the bladder. This is after the baby's born. And you could see the urine in the vagina and the uterus. And this is what it looked like in utero. This is how it looks on fetal MR. And on the VCUG, there's only one orifice that is cannulated filling the vagina and the bladder.

For those who like flow charts. If we take all cases of urinary tract dilation and talk about whether it affects the kidneys only or kidneys plus if it's only the kidneys and it's symmetric, a lot of these cases are mild, they're idiopathic, maybe they're associated with aneuploidy. So we have to do risk assessment of the patient. If it's moderate and severe and affecting only the kidney, it's most likely a UPJ obstruction. What if it's affecting the upper pole more than the lower pole? Remember that this could be a duplication anomaly. The key is to find the ureterocele. What if it's affecting more than the kidney? Then I think it's important for the next step is to look to see if it's a male or female. Male fetuses will have posterior urethral valves more commonly than prune belly, but that's the big differential. Female fetuses are more likely to have cloaca than urethral atresia. So the fluid filled structure in the female is less likely to be a dilated bladder and more likely to be a dilated vagina and a cloaca.

Bladder Exstrophy

Okay, the final case that I'm gonna talk about is a situation that we can often make the diagnosis by referral, of by, by the phone call referral alone. And usually the phone call goes something like this. I have a case, there's no bladder, there's never been a bladder, but the fluid is normal and I can't tell the sex of the baby. So no bladder, normal fluid disorder of sexual development. What is the diagnosis?

Let's look at some of the cases. So patient comes in, here's the cord insertion, umbilical arteries and there is no bladder. Slightly above that level. We can see this tissue which looks like possibly labia, but it's hard to identify what is going on with this tissue. And then slightly lower than this area of that tissue is what looks like a scrotum with two testicles. So does sagittal imaging help? Here's the cord insertion and here is that amorphous tissue. A little bit lower down. We could see what looks like a scrotum and a very small penis, but it is confusing.

Here are several other cases with the same diagnosis. Sagittal view of the cord insertion and this amorphous tissue, no bladder, that's a key finding. Again, cord insertion, amorphous tissue in another case with what looks like a scrotum and no bladder. 3D ultrasound cord insertion, very smooth amorphous tissue and scrotum.

So this is a diagnosis of bladder exstrophy. I end with this diagnosis 'cause it's a combination of abdominal wall defect and GU anomaly. Bladder exstrophy is from an inferior abdominal wall defect. So the defect is inferior to the cord insertion site and is basically a filet open bladder. So this is an exposed bladder which will have a variable appearance. It can be quite smooth or it can have these, nodularities because of exposure to amniotic fluid, always there's going to be a disorder of sexual differentiation. This, for example, is a male and this is epispadias. This is female, this is a female and the labia have been splayed associations include, epispadias, GU, pelvic abdominal wall, spine and rectal anomalies. And there is an, overlap with cloacal exstrophy, which often has omphalocele and spinal anomalies.

So it's a diagnosis to keep in mind when the bladder is not seen, the fluid is normal and there is abnormality of the genitalia.

Conclusion

Well, that's the end of my talk. Thank you for your attention. And scan away.