Pregnancy and pregnancy complications
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- [Voiceover] Okay, ladies. I'm gonna ask you to recall what's probably a really painful memory. And guys, use your best imagination with this one. You know when you're wearing fake nails? They're glued on really well to your actual nail. And when it comes time to remove them, you're supposed to soak them in some solution that dissolves the glue. But when you're super impatient, sometimes you rip the nail off. And sometimes, your actual nail very tragically comes off with the fake nail. And what's left is a nail bed that's bleeding profusely because the nail bed is a really vascular place, so it has lots of blood vessels running through it. So with that picture sort of in the back of your head, let's talk about the placenta. You have the uterus before there's any embryo, and the wall of the uterus is made up of three layers. On the inside, there's the endometrium, the endometrium, all the way on the inside. And then, the myometrium, that's myo, "myo" meaning muscle, because this layer is composed mostly of smooth muscle, myometrium, or the muscular layer in the middle. And that leaves the perimetrium, peri, "peri" for periphery, on the periphery of the uterus. Perimetrium, all the way on the outside of the wall. And it's the endometrium that's all the way on the inside that changes, that actually changes to prepare for the implantation of the embryo. And that process of change that the endometrium undergoes is called decidualization. It's a process where blood vessels grow profusely and glands in the endometrium become filled with nutrients, like glycogen. And at the end of this process, at the end of the decidualization, the endometrium is called the decidua. So it goes from being called the endometrium to being called the decidua. Now, looking at the embryo side of things, the outside of the embryo has these cells. The cells are called trophoblasts. Trophoblasts, that's what I'm putting in green over here, those cells called trophoblasts. And these trophblasts actually interact with the decidua. They're actually responsible for the embryo implanting into, or burrowing into, the decidua, to eventually form the placenta. Now, the reason why I'm going into such a detail about this process, about how the trophoblasts dig into the decidua, which, by the way, the part of the decidua that the trophoblasts interact with is called the decidua basalis. That's its specific name. It's called the decidua basalis. The reason why I'm going into detail about this is because of a set of disorders called placenta accreta, increta, and percreta. I know it sounds like the name of Cinderella's evil stepsisters. So in these disorders, the placenta is too firmly attached to the uterus. So instead of the placenta attaching to the decidua basalis, or attaching just to the decidua basalis, it attaches too deeply to the myometrium. And that's usually because a decidua basalis is defective, it's not thick enough. And a trophoblast needs more to grab onto. So they have to dig deeper into the myometrium. And, before I go into what causes defective decidua, let's lease apart the three evil stepsisters. So placenta accreta is when the placenta attaches to the myometrium. So it kind of attaches through the decidua basalis and attaches onto the myometrium. And that's called placenta accreta. Accreta. Right? Now, placenta increta is when the placenta actually penetrates into the myometrium. So it goes all the way through and really digs deeply into the myometrium. And that's called placenta increta. And finally, placenta percreta is when the placenta digs all the way through the myometrium and the perimetrium and sometimes will even invade into the adjacent bladder wall. And going all the way through those layers is called placenta percreta. All right. So why does this happen? How do you get a defective decidua basalis? A lot of times, it's the result of some prior surgery in the uterus. So, for example, a history of a C-section, a history of a uterine curretage, a uterine curretage, which is a type of procedure in which the lining of the uterus is scraped away, for a variety of different reasons, or a myomectomy, a myomectomy, which is another type of procedure that's used for the removal of fibroids in the uterus. So any one of these procedures can lead to a thin or scarred endometrium that doesn't form a juicy, healthy decidua. Another thing that can sometimes happen is that the placenta implants in a lower segment of the uterus, rather than at the top, like it's supposed to, which is a condition that's called placenta, it's called placenta previa. And the problem is that the lower parts of the uterus generally have thinner walls and they don't form as thick of a decidua. So these are a few of the things that can lead to a defective, or a thin and inadequate, decidua. And these risk factors are pretty significant, so much so that if a woman has has had three or more C-sections in the past and she has a placenta previa, she has a 50% chance, or one in two chance, of having a placenta accreta. So that's a type of situation in which you would probably be on the lookout for a placenta accreta. So you might wanna do some imaging on the uterus, such as an ultrasound or an MRI, because that becomes important in these cases. Now, I also wanna mention that there's some thought that sometimes, you can just have trophoblasts that are too aggressive in their implantation or in their digging. And that can contribute to the formation of this disease. Okay. So a lot of times, the way that the placenta accreta is discovered is at the time of delivery, when it's found that the placenta is really hard to remove. And when the practitioner sort of inserts their hand to manually extract the placenta, they find that it's really firmly attached to the uterus. Or someone might pull too hardly on the umbilical cord trying to pull the placenta out, and that rips apart the placenta from the uterus and leads to a lot of bleeding, kind of like when you rip away a fake nail, like we were talking about earlier. And really, because of that, because of the risk of bleeding, the best way to manage this disorder is with a hysterectomy, or a removal of the uterus right after the baby is delivered. And I know that sounds a bit dramatic. You might say, "Well, why can't we just "remove the placenta carefully, bit by bit? "Or leave it in there to come out on its own?" And the answer is that trying to remove it even very carefully puts the mom at risk for hemorrhage and even death. And leaving the placenta intact places a significant risk for infection. So really, the only option is hysterectomy. Only very, very rarely, in a very young woman who expresses a very strong desire to have children in the future, perhaps then an approach to conserve the uterus can be undertaken. If only there were a glue dissolver of sorts that could allow the placenta to gently peel away from the uterus, then perhaps in the future, we may have a way to avoid hysterectomies. But unfortunately not for now. So all in all, those are some details about placenta accreta, increta and percreta.