Dr. Chapa (7:17)
Fetal gastroschisis is a congenital abdominal wall defect that is different than omphalocele because omphalocele goes out through the umbilical ring. And with omphalocele, the intestines are still covered by a membrane. But in fetal gastroschisis, it's a defect of the abdominal wall. It literally is a true hernia where the intestines and at times, oh, it's rare. If it's big enough, it can include other issues in the right upper quadrant, like a little tip of the liver. But mainly, mainly it's isolated to the intestines, and they're freely floating loops when you do an ultrasound. And that's how it's diagnosed without a membrane. Okay, so this is why it's important. Even though we've got plenty of patients who come in with no prenatal care, they just show up like a week before they think they're going to deliver. Those patients need an ultrasound. I mean, they need an ultrasound. And I get it. It's too far to date. We're not going to date them with that. Unless something is overtly off, like you're six weeks off. Then you got to figure that out. But that's the extreme. But you really got to make sure that. So. Yes. So nothing catches you by surprise. I mean, you got to look at the intracranial structures, make sure it's not anencephalic. You know, you got to make sure the heart's okay and you don't have to call nicu. But it's like a two chamber heart. I mean, whatever. I'm just throwing stuff out there. And you got to take a look at the abdomen. Even though it's difficult to kind of appreciate this at term when things are all squished together, you're likely going to see this. Okay, so. So you got to get an idea. Even though it's not good for dating, unless you, again, are overtly off in the weeks, you just got to get an ultrasound to make sure that nothing sneaks up on you. Now, this patient that we're talking about here, that inspired this episode, you know, she had regular prenatal care, she has good dates. But during her, you know, routine ultrasound at 18 weeks, ish, this was seen. Okay? Now, you may not see this in the first trimester. I mean, it really depends on what's going on here, because first trimester is quite small. And, you know, defects may not be visible, of course, unless there's other things like a baccystic hygroma. But for the abdominal wall, it's very common to get. Hey, you got a good dating ultrasound. Looks like your little peanut. Little good crown, rump length. But then later on, as of course, things develop, you now see this big defect. Now, it's possible to, I mean, if it's a huge abdominal wall issue, to see that in the first trimester. But traditionally this is seen during fetal anatomy scans. Now, the good news, if you've got to find a good news in something, is that this is rarely associated with a chromosomal issue or a genetic syndrome. This is typically not syndromic, and that's been published many times over by large population based studies and registries that have found that, hey, it is possible that there could be a genetic issue in the background, but that seems to be a concomitant ride along versus a causative issue. Okay, now that's much different than an omphalocele, which is much more associated with possible chromosomal abnormalities like trisomy 18, 13. Those are, if you do see an omphalocele, it's an indication too. You can get cell free DNA, which is very good. But traditionally you want a good diagnostic test like an amnio, make sure nothing was misread. So while gastroschisis is considered typically an isolated defect just involving that ring to the right of the umbilical cord, the majority of cases to the right of the umbilicus of the umbilical cord insertion, this tends to be more isolated compared to omphalocele. Okay. The background prevalence, as we've said in the intro, basically around 2 to 4 or 5, based on who you read per 10,000 now, thankfully, and it's unclear why, but there seems to be since 2010, this kind of like slow decline from what it used to be at one time. It peaked earlier about 20 years ago. It was about 5 per 10,000. Now we're like 1.6 to 4.5. Again, 2 to 4 per 10,000. So it's kind of gone down a little bit. Some of that may be nutrition, some of that may be better diagnostic issues. But, but it, for whatever reason, I'll take it, it seems to be going down. Okay. And that also is seen in other parts of the world, not just in the U.S. but there are some, some small differences based on who you look at. For example, in Denmark it's been reported about 1.6 per 10,000. Canada 3.4 per 10,000. So basically in general, we're still talking about the general range. If somebody asks you how common in this and the answer is, well, it's not very common, but it's not rare either. I mean, it's kind of in the middle and depends on how you look at it. But in general, about 2 to 4 per 10,000 will be diagnosed with this. Now here's a good clinical pearl. Okay, for whatever reason, is it nutritional, is it stress, who knows. But gastroschisis is more common to younger women. In other words, those under the age of 20. This seems to exceed a rate or be around 10 per 10,000 live births. So it's kind of double, double that in other populations. So it's wild, it's not influenced by the sex of the Child. So a boy baby or a female baby is not more likely to change that. But again, there are some geographic, some socioeconomic factors that may play a role here with lower socioeconomic status having an increased risk. But one of the more accepted risks, and it's a good one, in case they ask you, is lower maternal age. Lower maternal age, like in the teenage years. All right, in terms of causation, I mean, it's not really known what does it. It may be a combination of genetic predisposition. Maybe it's an epigenetic issue. Definitely something intrauterine environmental. But the idea is as that umbilical wall is forming, of course there's some kind of defect. There's a vulnerable area of vascular disruption in the abdominal wall, which could be genetic, it could be maybe infectious, it could be a thrombus issue. Maybe there's a little clot and affects the closure of the abdominal wall. But something impairs abdominal wall development and you get this hernia. Okay, now you know semathod, is it related to part of the umbilical cord vessels as they through the abdominal wall? Maybe it's. But again, unclear. We just know that almost universally this is something that happens to the right of the umbilical cord insertion. So the right of the belly button. Okay, to the right of the belly button. Now, outside of young age, which we get, there are things that again make this more likely. Anything that affects vasculature, so amphetamines, anything that gives you basal constriction, that's a risk. Smoking, of course that's a risk. Lower bmi. Remember we said possibly some nutrition things, some environmental issues, it could be a nutritional deficiency. So lower BMIs tend to go with this. These have been linked epidemiologically or associated epidemiologically to this finding. All right, so lower age, smoking, lower bmi. Some have said maybe a pesticide exposure, but it's just so difficult to point this out. So the short answer is, I don't know. It's kind of random, kind of multifactorial. Definitely some epigenetic possibilities. There definitely some environmental issues. Most likely it's something called a two hit effect. All right, so there's hit into the abdominal wall. The abdominal wall is like, oh, I'm not digging this. I'm not coming together, I'm not forming correctly. And then as the organs put pressure on that defect, there's where you get the evisceration in utero. Right. So that's the two hit theory where the first hit is the Abdominal wall defect. The second hit is the actual protrusion of the bowel into the amniotic fluid. Okay? And so that's the issue here. It's not the defect itself that's bad. It's the effect of chronic exposure of the intestines to the amniotic fluid. You're thinking, well, what's wrong with the amniotic fluid? I mean, it's just fluid, right? Well, there's substances in the amniotic fluid, Remember? Especially over 20 weeks, a part of that is baby urine, and it's just that exposure the intestines, guys, let's just make it clear. Supposed to be inside the body. Surprise, surprise. So once they're outside, that constant bathing and potential trauma as a child moves can cause some issues here, and it depends on how much is coming out of the defect. I mean, they can strangulate, they can have a bowel necrosis, they can have a volvis. These are bad things. Okay, so gastroschisis, it's very dichotomous here, and that's why you got to follow these up, because we get into the potential adverse issues here neonatally in a minute. But you got to follow these up because. Just because it looks like a small defect when you see it at point, whatever, 22 weeks, more bowel may come out later on down the road. Plus, if that bowel starts looking edematous, swollen, strange echolucencies in that, that's a bad sign. And so you got to figure this out how things look by ultrasound. We'll get the classification here as either simple gastroschisis or, like, look, it's a little bit of a defect. Bowel seems to be okay. Yes, it's herniated through the abdominal wall, but it doesn't seem to have any kind of perforation or necrosis. There's no bulbolus. Looks otherwise healthy, so you got to follow that. And then there's complex gastroschisis, which is everything that. That is not right. So we're talking about bowel atresia. There's stenosis, there's dilation, there's visible volvolus. These are complicated cases that absolutely are associated with increased neonatal morbidity. They have longer hospital stays. They have delayed feeding. There's higher risk of surgical complications, and, of course, just overall adverse issues. All right, so the two main buckets for gastroschisis are simple and complex. Thankfully, right now for our patient. You know, though, things change. Right now, it seems to be a sympro Gastroschisis bowel looks otherwise healthy and no issues. But, man, does this have to be followed up. As we've already talked about, the diagnosis is almost universally by second trimester ultrasound, where you see the free floating loose in the amniotic fluid that's separate from the umbilical cord insertion. Now, old school. It was at elevated MSA of P. Remember we talked about this in the previous episode? Okay, so everybody links, of course, elevated maternal serum alpha fetal protein to a neural tube defect, which is the majority of cases, but it also is linked, as we covered in that episode, to abdominal body cavity defects like this. Sometimes you can do Doppler, you can see where the umbilical vessels enter. You can see where the defect is. That's how you can really see. That's to the right of the umbilical vessels. But in general, this is isolated. This is not related or associated with other anomalies. So that's a good sign. Doesn't mean you don't look for it. So you got to look for it. You got to. Do you recommend cell free DNA even though it's not typically associated with a genetic issue. You don't want to miss anything else. All right, so gastroschisis diagnosed by ultrasound Doppler can sometimes help. Old school. It was maternal serum alpha fetal protein. And as we covered in that. We covered in that episode. Do we check MSAFP, even though we always get a level 2 ultrasound fetal survey, the answer is yes. Yes. And we covered that in a previous episode. We're not going to go into that now, but if you're interested, go back and listen to that. Well, why would we do that if we can just see things? Because you're trusting humanity's eyeballs. And so as a double screen, it does make Sense to get MSAFP. Plus, even when MSAFP is elevated above 2.5 multiples of the median, without anomalies, there are increased risks of adverse issues. I'm not gonna tell you which ones they are, because you gotta go back and listen to that episode. All right, here's what we're gonna talk about next. Why don't we take a little break because I need more coffee. And then we're gonna come back, we're gonna talk about what does this mean for the pregnancy? Is this linked to any other issues? What about management options? Does this need a C section? And then we're gonna talk about potential repair. Even though I'm not a pediatric surgeon, you gotta have a good relationship with your pediatric surgeons. Here because they'll do this traditionally, either one way or based on whether it's simple or complex. Gastroschisis. And how that bowel looks at delivery. How that bowel looks at delivery. All right, so I think we'll take a little break. We'll come right back and we'll talk about the follow up of fetal gastroschisis. We'll be right back. You're listening to the OBGYN no Spin podcast. What can I get you? I'd like a large coffee. Okay. So hot coffee, hard coffee. Okay. Room for cream. Totally leave room for cream. Why are you talking like that? Why are you talking like that? Well, going to a coffee shop has become kind of an adventure and kind of an ordeal, hasn't it? I mean, from our beloved baristas who ask you if you want room for coffee. Room for cream. Like, I can do it to just the $10 cup of coffee, y'.
