Umbilical cord dopplers: AEDF and REDF! How is the BABY affected?

Imagine that you're called to a delivery of a 28-weeker, and before the delivery you're told IUGR and AEDF. What does that actually mean? Well, that is what we're going to be talking about today. But before I start, I want you to consider two questions. The first one is, what is worse, absent or reverse end diastolic flow? And the second one is, what do these abnormal dopplers actually tell us about the baby? Stick around to the end and you'll be able to answer these so easily. Hi, I'm Dr. Tala, a board-certified neonatologist. So, a neonatologist, not an OB. So the emphasis of this video is not going to be on actually obtaining the ultrasound pictures, but rather what we need to know about what all these acronyms mean if we're taking care of the baby. In this video, we're going to go over, one, the placental structure and physiology generally. Two, blood flow during pregnancy and what happens when it goes wrong. Three, how abnormal Dopplers actually affect the baby. And four, recommendations on monitoring and delivery of these babies with abnormal Dopplers. Let's start with one, the placenta. As you all know, the placenta is a temporary fetal maternal organ that is responsible for connecting the fetus and the mother and for providing the oxygen and nutrients that the fetus needs and getting rid of the waste products that the fetus doesn't need anymore. And it's also responsible for producing hormones during the pregnancy. It truly is a remarkable organ. The placenta itself is mostly formed by the embryo, but obviously we need some sort of maternal blood supply to be able to feed into the placenta. This is done with the maternal spiral arteries. I know we're getting into the weeds a bit, but hear me out here. I promise this is going to be relevant. In the non-pregnant state, the spiral arteries are narrow, high-resistant muscular vessels that will constrict and dilate to kind of regulate the maternal flow. In the placental bed, during a healthy pregnancy, these spiral arteries undergo a complete transformation. During pregnancy, fetal cells called extravillous trophoblast We'll basically invade these spiral arteries and in this way these spiral arteries get transformed from these really skinny pulsatile vessels into these wide low resistant dilated vessels that are capable of allowing large quantities of maternal blood. So this blood can go into this intervillous spaces and completely bathe the fetal chorionic villi. What if this remodeling remodeling actually goes wrong though. So, sometimes, in many cases of placental insufficiency, these spiral arteries, instead of becoming nice and large and dilated and low resistance, will stay on the skinnier side and stay more muscular. So, obviously, in this situation, not as much blood can be poured into that space. So, these fetuses will end up with some relative hypoxia, and there's going to be more resistance to blood flow. Eventually, this ends up with just increased pressures in the placenta. Two, flow of blood during pregnancy. So let's just remind ourselves of basic placental physiology. Remember that deoxygenated blood leaves the fetus through the two umbilical arteries. The deoxygenated blood travels through the umbilical arteries until it reaches the capillaries in the chorionic villi. Like we said, the mother's blood is all in the intervillous space and we get oxygen and nutrient transfer from the intervillous space into the capillaries of the chorionic villi. After that blood has the oxygen now, it then travels back to the fetus in the umbilical vein. So just to emphasize, the umbilical arteries are carrying the deoxygenated blood to the placenta, and the umbilical vein is carrying the oxygenated blood from the placenta back to the fetus. Usually, blood is flowing continuously through the umbilical artery. So all the way through systole, when the fetal heart is actually contracting, As well as through diastole, when the fetal heart is actually relaxing. But like we said, if the resistance to blood flow and the pressures increase in the placenta, then now the umbilical artery is seeing a higher pressure that it has to flow against. So systole is rarely affected until the very end because the heart is generating high pressures. But during diastole, the pressures are much lower in the umbilical artery. So as the resistance and the pressure increases in the placenta, we can sometimes see worsening of the diastolic blood flow through the umbilical artery. So what the OBs and ultrasonographers are actually measuring is the presence, the direction, As well as the velocity of the flow through the umbilical arteries. Again, the umbilical arteries are going from the fetus to the placenta. Initially, if the pressures are normal in the placenta, then there is normal diastolic flow. But, as the pressures slowly go up, we have worsening of that diastolic flow. Initially, the OBs might just call it decreased diastolic flow. So, there's still flow during diastole going in a forward motion, but that flow is slower and it decreases. Sometimes we're also told there is an elevated SD ratio, or systolic-diastolic ratio. This is also indicative. of placental insufficiency or increased pressures in the placenta because if the systolic flow is normal, like we said, it takes a lot more to affect systole than diastole. If the systolic flow is normal and the diastolic flow is going down, then the ratio of SD is going to be higher. So an elevated SD ratio is also indicative of increased placental resistance. If the pressures in the placenta continue to go up, Then not only do we have decreased end diastolic flow, we could have absent end diastolic flow. So that blood flow is no longer going forward at all. And then if it's really bad, really high resistance to flow, really high pressures in the placenta, then we may end up with reversal of end diastolic flow. So instead of the blood continuing from the fetus to the placenta, it actually goes backwards. So reverse end diastolic flow is at the end of diastole. The blood is actually going from the placenta back up the umbilical artery towards the fetus. So the gradations of increasing pressure in the placenta is normal, so no issues with the placenta, decreased end diastolic flow, absent end diastolic flow, and then reversed end diastolic flow. Another equation that you might hear that the OBs are using is the pulsatility index or the PI. Basically, the higher the PI, again, The more resistance to flow, the higher the pressures in the placenta. And the actual equation for the PI is the peak systolic velocity minus the end diastolic velocity divided by the mean velocity. So logically, again, as that diastolic velocity goes down, then you are going to end up with a higher PI. So also indicative of increased placental resistance. Number three. How does this affect the baby or the fetus? Well, as people that always take care of these babies, obviously we're very aware of the effects of placental insufficiency on the babies. And we know that what lacking oxygen and nutrients can actually do to these fetuses and nutrients. We also know that what the fetus initially tries to do is compensate for this lack, relative lack of oxygen. So as we've talked about multiple times on this channel, If a baby lacks oxygen, then what they're going to try to do is divert the oxygen and the nutrients that they do have to essential organs. In the fetus, this is the brain as well as the heart. So that is why that babies that went through placental insufficiency in utero can often be born asymmetric SGA. So their bodies, their weight, might be less than the 10th percentile, but because the baby was trying to send all the oxygen and nutrients that it could to the brain, the brain and therefore the head size might be AGA or appropriate for gestational age. So you end up with these scrawny little babies with relatively larger heads because the baby was appropriately distributing the oxygen and nutrients to the most necessary organs. Obviously, as the condition worsens, as we've got Bad reversed end diastolic flow, then eventually the brain and the heart will be affected and eventually the fetus will literally not be getting enough oxygen and nutrients even to survive. So it is important to catch this before it becomes too late. Often changes in the ductus venosus flow will indicate that the fetus heart is in trouble. So, this is another Doppler that the OBs might sometimes tell us about. So, remember that the ductus venosus is one of the fetal shortcuts from the umbilical vein. It kind of goes through the liver and then it meets the inferior vena cava just outside the heart. So, logically, if the heart is failing and we have increased pressures in the heart, Then that, then the ductus venosus. is not going to flow as well towards the heart so basically if you're getting abnormalities in the ductus venosus flow so for example an absent or reverse a wave not going to go over those now then we are now not just worried by increased placental resistance but by actually having issues with a failing heart this is a very poor sign again remember that the umbilical artery dopplers tell us more about the placental resistance Whereas the ductus venosus flow tells us more about the fetal cardiac status. As you all know these babies that do suffer from placental insufficiency in utero are often delivered early deliberately. So whether the mothers are induced or more often they're delivered by c-section just to get the babies out. Because at some point the risk of staying in utero and getting less and less oxygen and nutrients becomes a higher risk than being delivered prematurely with the effects of placental insufficiency so probably prematurely as well as IUGR as well. So unfortunately these babies not only have the increased risk of being born pre-term but often just being SGA or IUGR they have increased morbidities for that gestational age so increased risk of IVH, of NEC, of BPD, even of neurodevelopmental abnormalities. Even if they are delivered later, these babies are also at increased risk for respiratory distress syndrome, temperature instability, hypoglycemia, as well as just a longer hospital stay. So being born small, having experienced placental insufficiency is not without its risks. They also have common blood abnormalities like leukopenia, neutropenia, thrombocytopenia. Polycythemia or higher hematocrit as well as like we keep saying hypoglycemia. I do just want to say that these are slightly increased risks. It doesn't mean that if a baby has some level of placental insufficiency they're definitely destined for a worse outcome. But we all have to be aware of these risks so that we can intervene accordingly. Four, recommendations on monitoring and delivery. And here we're kind of going into OB territory. But I figured I should include this as well. Obviously, as soon as any decrease is seen in the end diastolic flow, these babies should be monitored very carefully. They should be monitored for their overall weight gain because, again, we keep saying that that's a sign that the baby isn't getting enough oxygen and nutrients. So a lot of these babies do end up being IUGR. And they should also be following serial umbilical artery dopplers on these babies. Sometimes, often actually. The fetuses are found to be IUGR or just very small, but initially the umbilical arteries might be okay. Obviously, if at this point they're just seeing a small baby, then other workups should be done as well. For example, a full TORCH investigation should be done. Sometimes the size of the baby being small can precede actually having abnormal dopplers. Obviously, the decision to deliver the baby is the balance between what is going to be worse, the baby staying inside the mother and getting less oxygen and nutrients, or the baby being born early and suffering the consequences of prematurity and also being SGA. Obviously, that's going to depend on the severity of the disease, as well as the gestational age of the baby. For example, if a mother presents at 34 weeks and is found to have reverse end diastolic flow on the Doppler's? That's a pretty easy decision to actually deliver that baby at 34 weeks. Obviously, this is a harder decision to make at 22 weeks. Various national and international organizations have written out protocols recommending how these mothers should be monitored and when they should be delivered. Obviously, the fact that they are even a little bit different means that there is no exact science to this. And I think a lot of the times the OBs are taking each patient individually and following the overall picture, as well as incorporating these guidelines. So, for example, the Society for Fetal and Maternal Medicine has different gradations based on how bad the placental resistance is. So if there is an elevated PI, pulsatility index, but there still is forward flow during end diastole, then they're like, it's okay if the baby's delivered at 37 weeks, but these mothers should be monitored a lot more closely with the umbilical arteries, probably weekly as well as non-stress tests. With any concerns, then obviously more intervention should be done. For absent end diastolic flow, the... Society for Perinatal and Maternal Medicine says that these babies should be delivered between 33 and 34 weeks, but they should be getting umbilical arterial dopplers two to three times a week, and they can consider inpatient admission depending on how everything looks. Obviously, delivery should be done earlier if there are any other abnormalities. And for the worst indicator of placental insufficiency, the reverse end diastolic flow, they recommend that these mothers are admitted to the hospital. They receive the prenatal steroids, and the testing is done one to two times a day. These babies should be delivered between 30 and 32 weeks. FIGO, or the International Federation of Obstetrics and Gynecology, is even a little bit more conservative about when to deliver these mummies. So if there is absent end diastolic flow, delivery should be between 30 to 34 weeks, but they also recommend doing monitoring a lot more frequently than two or three times a week. If it's reverse end diastolic flow, then again, babies should be delivered between 30 and 32 weeks. If there is an abnormal ductus venosus flow, which we said, this is starting to indicate cardiac compromise, then obviously, as everything else, these cases should be individualized, but these babies should probably be delivered as early as 26 weeks. Obviously, as all these protocols go through, if there's any chance that these babies are going to be delivered early, then the mothers should be given prenatal steroids, and if delivery is more imminent, then the mothers should also be given magnesium. for neuroprotection. I have listed these references below so you can look at them in more detail. Well I hope that you learned something. I feel like we hear those words so often and I think they can be quite confusing to a lot of us. If you reach this far then please like this video and if you're interested in more neonatal education then please subscribe Subscribe to our channel. Thank you so much for being here.