Welcome to Monoamniotic.Org, the web site for expectant and experienced parents of monoamniotic twins! While the Introduction Letter gave you an introduction to our group, it's my job to welcome you to our site and tell you a little more about what monoamniotic twins (multiples) are. First of all, we're glad you came. This group was formed by experienced and expectant parents reaching out to each other to help support each other through the difficult times. We come from all over the US, as well as abroad (Canada, Australia, Japan, and Germany to name a few). For some, these are our first children, for others, they are two extra bundles of joy to add to the others. We are here to help.
Just what are "Monoamniotic Twins"?
In order to understand what "monoamniotic twins" are, let's first look at twins in general. There are two types: fraternal and identical. Fraternal twins are created when two separate eggs are fertilized by two separate sperm. While some fraternal twins look stunningly alike, they are nevertheless the product of two separate fertilizations. Generally speaking, fraternal twins are said, on average, to share about 50% of their genes - the same as any other two siblings. Identical twins, however, are created when one egg is fertilized by one sperm, and some time after fertilization, this single egg miraculously splits, forming two distinct embryos with the exact same genes. Identical twins always share 100% of their genes, and while most look very much alike, it is not uncommon for them to have somewhat different appearances, and occasionally very different appearance. Therefore, appearance alone cannot differentiate between fraternal and identical twins. Identical twins are also always the same sex. Since they share 100% of their genes, they would have to be! No one knows exactly what makes the egg split. It appears to be random, occurring approximately 1 in every 250 pregnancies. This statistic has held true across cultural boundaries and time (unlike fraternal twins, which are on a steep rise). Monoamniotic twins are always identical. So now let me tell you more about why...
When the egg splits is an important fact. To understand why, you'll need to understand a little about the biology of the forming embryo. One of the first things to form is the yolk sac. To my surprise, when I looked this up, it seems that no one is completely sure what it's for. The current assumption is that it exists to nourish the forming embryo. The one important thing to know about the yolk sac, though, is whether there are two yolk sacs or only one. I'll get back to this in a minute. The placenta and chorionic sac begin to form probably about the same time. After that, the amniotic sac forms. Imagine these three sacs as three balloons surrounding the baby. (To be technically correct, the placenta isn't really a "balloon" - but for the purposes of this example, we'll think of it that way.) Now, if the egg splits before the placenta has formed, each baby will have their own placenta, chorionic sac, and amniotic sac. This is uncommon, but it is possible, and it is why having two placentas doesn’t necessarily mean the babies are fraternal twins. If the egg splits after the placenta has formed (within a few days after conception), then the two babies will share a placenta and chorion, but will have their very own amniotic sac. But if they split after the amniotic sac has begun to form (estimates range between 7 to 9 days after conception), then both babies will have to share an amniotic sac. This is what we mean when we say "Monoamniotic Twins". Again, no one knows why the egg splits exactly when it splits anymore than they understand why they split in the first place. Obstetricians and Perinatologists will also sometimes refer to this in shorthand as "MoMo twins" for Monochorionic and Monoamniotic. Another acceptable term is Monoamnionic (with an "n" instead of a "t"). All are correct, but the most common term is Monoamniotic (and is also the namesake for our site). Other terms that we have heard used related to this type of pregnancy are "mono amniotic twins", "One sack twins", "One sac twins", "Twins in the same sac", "no membrane", "monoamniotic membrane", “mono twins”, "one septum". These are only a few of the phrases that my be tossed around by the medical (and not so medical) communities. Please note that monoamniotic triplets may form as well. We have had one couple with monoamniotic triplets with us, and have had a handful of triplet pregnancies with a momo pair.
Back to that yolk sac... First of all, you have to have an ultrasound at a very early time to be able to see a yolk sac. It disappears gradually as the babies develop. But more importantly, there is some research that states that the number of yolk sacs corresponds directly with the number of amniotic sacs. 2 Yolk sacs = 2 amniotic sacs. There is a physical reason behind this – it’s not just a coincidence. So if you have had an ultrasound early enough to be able to see yolk sacs, ask your doctor how many there were. Most likely, if you saw two yolk sacs, you have been misdiagnosed. This is not always true; however. Sometimes, a misdiagnosis can result because the ultrasound machine being used is not of sufficient resolution to be able to see both yolk sacs, even though they are really there. And in the case of one member here, although they saw two yolk sacs, she was later confirmed to be truly monoamniotic. Her doctors couldn't explain how or why that happened, but it did. So it is not an absolute rule; however, it is very likely that if you were able to see 2 yolk sacs, you do have two amniotic sacs. It is at least reason to continue looking for a membrane until and unless you have separate confirmation of the diagnosis. (See the section below "Are they sure they're in the same sac?")
What does it
mean when they say I'm carrying Monoamniotic twins?
This means that both babies share the same living space. They don't just share their house, they share a bedroom, bathroom, and playroom. While it is still possible even for a singleton to become tangled in his or her own cord, monoamniotic twins have to worry about becoming tangled in their sibling's cord, too. Cord entanglement (also called "Cord Accidents") are the number one risk in this type of pregnancy. However - to put this danger in perspective - virtually all cases of monoamniotic twins will have tangled cords. (There are a few very, very rare cases where it is found after birth that there was no entanglement at all. But for the purposes of pregnancy management, it should be assumed that they all will become tangled to some degree.) It appears impossible for two babies to exist in the same sac without at least twisting their cords. So simple entanglement is *not* a death sentence! In order for entanglement to become dangerous, there must be cord compression. It is very possible to have entanglement apparent as early as 10 weeks (and probably even earlier), and still have both babies delivered safely at 34 weeks with no complications. We have had several parents here who saw entanglement at their initial diagnosis ultrasound. It is very likely that the majority of tangles begin during the first trimester when there is so much extra room to move around in. So even if you see tangles from the very start, that does not necessarily mean that you will have serious or fatal cord compression before you can safely deliver them. Nevertheless, as cord entanglement is the first sign of possible problems, that is what Obstetricians and Perinatologists will give the most amount of attention to. The weapons they have at their disposal in this fight are ultrasound, doppler imaging (a way of seeing actual blood flow through the cords), and fetal monitoring. With these tools, it becomes easier to detect problems early, before they become insurmountable.
We wish we could tell you that there was some kind of procedure that could be done to "fix" this condition, but there's not. There is one medication (called Sulindac) that reduces amniotic fluid volume in hopes that reduced fluid will also reduce movements of the babies. However, it is very experimental. Preliminary studies have shown good results; however, there are no long term studies on the side effects of Sulindac on either the mother or the babies. If you would like to consider this treatment, we urge you to discuss it with your perinatologist to get a better idea of the potential risks and benefits. Other than Sulindac, there are no "treatments" that actually try to prevent entanglement or compression. The only "treatment" doctors can offer is delivery. If they discover serious problems before 24-26 weeks (the point of viability outside the womb), there's nothing that can be done. After that point, if they discover life-threatening problems, they can deliver. However, the earlier delivery occurs, the higher chance that they may suffer from the complications of extreme prematurity.
While some cord accidents are sudden, it appears that the majority of fatal cord accidents are gradual. And the majority of those will show symptoms that can be detected via high resolution ultrasound and/or fetal monitoring (i.e. Non Stress Tests or NST's). That means if you are watching often enough, you will probably see the signs of compression in enough time to do an emergency delivery before it is too late. So as you can see, the key to management of a monoamniotic pregnancy is monitoring. How much and how often is a question that you will have to address with your perinatologist. Unfortunately, there is no consensus of a "best" treatment plan in terms of the frequency of monitoring. Generally speaking, more is better, up to and including 24/7 continuous monitoring. There has been a recent push to use continuous monitoring, as some recent studies have shown not only higher success rates with 24/7 monitoring, but also later deliveries than those monitored less frequently. Nevertheless, there are a lot of details that must be considered when making this decision, such as financial concerns, caring for other children, or the sheer inconvenience of either traveling to the hospital repeatedly for NST's, or the inconvenience of being hospitalized for an extended period of time. So that decision is best made between you and your perinatologist, weighing all the concerns.
One other thing that having monoamniotic twins means is that you will deliver via c-section, prematurely. How early is also a debatable matter. Some doctors advocate 32 weeks, others 34, and yet others 36. The idea is to balance the risks outside vs. the risks inside. Once you get to 32 weeks, the scariest of the preemie problems are usually past. At 34, all but minor preemie problems should be past. And at 36, they are almost considered full term. However, there is evidence that carrying past 36 weeks increases the risk of fetal death. So, given the fact that there are almost no prematurity risks at 36 weeks, there are very few reasons to carry beyond that point, and a LOT of reasons not to. Nevertheless, you have to weigh the risks of prematurity at each of these milestones with the risks of staying in utero - which are considerable. The longer they stay in, the more chances there are for fatal cord accidents.
As for delivering by c-section, that is very important. If there is entanglement, there is the possibility that neither baby could be born vaginally because they are "tied" together so closely. Even if there is only minimal tangling, the risks of cord prolapse (where the cord of the second baby is "born" at the same time as the first baby, thus compressing the cord and possibly causing irreparable damage to the second baby) are too high to dismiss. Admittedly, there have been monoamniotic twins born vaginally and at term who were completely healthy. There have even been a few cases reported in the literature of safely delivered monoamniotic twins, encouraging others to attempt it themselves. We've also had a handful of parents find us years after the birth of their children, who were shocked when they realized all the risks they had faced without knowing. After all, this condition was impossible to even diagnose before ultrasound came along, and yet there were still healthy babies born. However, the risks of both carrying to term, and of attempting a vaginal delivery are so high that few doctors are willing to risk their patients on them. And anyone whose doctor encourages an attempted vaginal delivery should think very carefully about the risks and whether they are willing to take them for the minimal benefit of a potential vaginal delivery, which could easily end up being an emergency cesarean delivery.
Another thing that you should expect from this type of pregnancy is a referral to a perinatologist. That word has been tossed around several times on this page, but what it means is a specialist in high-risk pregnancies. The newer name is "Maternal-Fetal Medicine Specialists” or MFM’s. No matter what you call them, they have more experience and knowledge of how to deal with this type of high-risk pregnancy. Even if your obstetrician or family physician is comfortable taking care of you, you will still want at least a consult from a specialist. After all, this condition is so rare, it would be unrealistic to expect every OB to have studied it and to know off-hand what a proper management protocol is. Most OB's will give you this referral immediately, but others may need to be "prompted" by a request. Some OB's will willingly do research on their own to learn more about it; however, as long as there is a specialist available, one should be involved. Some perinatologists will take over complete care of your pregnancy, while others will simply consult with your OB through the pregnancy, advising of what to do at each stage. Either way, you will have the benefit of more experience and knowledge, and you deserve that.
So lastly, you'll want to mentally prepare yourself for not only a complicated high-risk pregnancy, but also a premature c-section delivery, and very probably a NICU stay as well. We know what an enormous burden that is, emotionally. Losing the hopes for a "normal" pregnancy and delivery is a true loss. All of us have been in the same place you are, and we know how hard it is. That's one of the reasons we're here to help!
Are they sure
they're in the same sac?
What may be the best news of all is that the amniotic membrane can be very thin. So thin, that's it's extremely hard to see on an ultrasound. So misdiagnoses are common. If the diagnosis was made before 8 weeks, it is definitely not certain. It is simply not possible to get a reliable determination of whether a membrane is present or not before 8 weeks. After that point, there appears to be a window around 10 to 12 weeks where the membrane is easier to see. Others note a window at 16 to 20 weeks. So if you are diagnosed before that time, you may want to ask for a repeat ultrasound during one or both of these timeframes. However, what appears to be far more important in accurately determining whether a membrane is present is the use of a high resolution ultrasound machine. Many times, and OB will refer a patient to a specialist, convinced the babies are monoamniotic. But often with the aid of a higher resolution machine, and years of high-risk obstetric experience, the specialist is able to find a membrane.
Some doctors are reluctant to make a referral to a perinatologist so early in a pregnancy, thinking that there is nothing the specialist can do that the regular doctor cannot. And with the exception of a more accurate diagnosis, that is mostly correct. However, waiting until 20 weeks before a referral means that you may have missed your best chance at finding a membrane. It is worthwhile to press your doctor for an early referral if for no other reason than to get a more accurate confirmation ultrasound.
Many of us do not find out that there are even twins, much less whether there's a membrane or not until much later. In those cases, there is still a good chance that the membrane was just hidden. Several people in our group found out at fairly late ages (28 weeks in some cases) that they were misdiagnosed. So unless you've had a definitive absolute diagnosis (see below for some of the ways that can be done), there still may be hope for a misdiagnosis.
Some of the tests they use to determine if the babies are truly in one sac are done through amniocentesis. If the doctor will be doing an amnio (for any reason), it is likely that during the amnio they will perform another test to try to find a membrane. One is called "the bubble test", the other "the dye test." During a "bubble test", they will insert a small bubble of air into the amniotic cavity next to one baby. Then they will roll the mother over while still doing an ultrasound and see if the bubble travels to the other side (next to the other baby) unhindered. If it does, they will assume there is no membrane. The "dye test" involves injecting dye into the amniotic fluid next to one baby, then withdrawing fluid next to the other baby. If the fluid next to the second baby is also dyed, then they probably share a sac. Probably? In rare instances a membrane may be so thin that the babies have punctured it thus the dye (or bubble) can still get across. One member had the equivalent of a "volleyball" net membrane - poked full of holes. Sometimes these "volleyball nets" are sufficient to keep the babies from becoming entangled; however, it is best to assume that it will not and act accordingly.
One other diagnostic criteria they use to determine if the babies are truly in one sac is the presence of tangles. If they can clearly see tangles in their cords, then that pretty much conclusively determines that there is only one sac. Even if there is a "volleyball net" membrane, that's irrelevant - obviously it didn't keep them from becoming entangled, so it is safest to consider them monoamniotic and proceed with managing the pregnancy as that way.
What about TTTS?
Twin to Twin Transfusion Syndrome is possible with monoamniotic twins. Until recently, it was thought that it was less common with monoamniotic twins than with monochorionic, diamniotic twins. However, some recent research states that the incidence of TTTS is virtually the same in both groups. Nevertheless, it may be more difficult to diagnose when the babies share a sac. One of the key indicators they use in diagnosing TTTS is the amount of fluid in the two sacs - if one has a whole lot, and the other has very little, that suggests TTTS. However, with only one sac, that is impossible to determine. So the main technique they will use to diagnose TTTS in a monoamniotic pregnancy is size discrepancy. Basically - whether one baby is of drastically different size than the other. Another important diagnostic clue is the condition of the bladder. In TTTS, one twin will have a very large bladder, but the other will have an almost invisible bladder. More information is available about TTTS from such groups as the TTTS Foundation and Twinhope. You will find information regarding what TTTS is, how it is diagnosed, and how it can be treated there. Links to these groups are on our Home Page.
Where do I go
I hope that you will find a lot of useful information on this site, but I think the most helpful part of this group is its members. We have Bulletin Board Forums here that you can access easily. Don't hesitate to "jump in" and ask questions. We even have a "Story Board" where you can read "real life" stories from other parents who have been, or are still going through a monoamniotic pregnancy. Please feel free to contact us or to explore our site further. We try to focus on the positive, and the things that you actively can do to help manage your pregnancy. While there is a lot that you can't do, we think it helps to focus on those things that you can. We have been accused of offering "false hope" to parents because even after doing everything right, they still lost their babies. Sadly, we have to admit that that does happen a lot more often than anyone likes to admit. We don't want to minimize the risks. However, that does not mean there is not still reason to hope. At the worst, there is at least a 50% chance of survival, and most likely it's much higher than that when the pregnancy is managed well. And while no one can quantify the benefits of positive thinking, it's easy to see that negative thinking doesn't help either. So please, don't take our positive attitude as one of dismissing the risks. It is simply a decision to focus on the positives rather than the negatives, and to give hope to parents when they may think there is no hope left. We hope you will join our group and share your experiences with us, and help other parents worldwide to deal with this complicated and heart-wrenching pregnancy.
Keep the Faith,
Monoamniotic Support Group Volunteer