Why is it that trained OB/GYN's are so ignorant to the fact that 2 sacs does not always mean fraternal twins?

Question

I am 4 1/2 months pregnant with twin boys who have separate placentas and sacs. It's sad that I had to find out via the internet that I have a slight chance of having identical twin boys, when my Dr. and everyone else dealing with this pregnancy siad that they just HAD to be fraternal, that it is NO way that they could be identical. What is the problem? From my research on the subject, 33% of identical twins shared bothe the same sac and placenta. Don't you think that the Dr. should have know this? Are there any parants of twins that have gone through the same thing?

Adam Z, you are obviously ignorant to the fact. I am getting research from reputable MD websites! I am also talking to REAL people that have identical twins who did not share the same placenta or sac. So there, I'm no idiot, I'm a nurse and I'm not being to hard on the Dr's, but as a nurse we are encouraged to take refresher courses, but it's sad that most MD's think that they are above that!

Answer 1

You are indeed correct..although I have heard this before...my girls were in one chorion but had two amnion and one placenta...picture two balloons inside one big balloon..the tech who did my first sono said the same thing (fraternal)..when I went to the specialist, due to preterm labor..she said it was evident that they were identical because of the thin membrane that separated them...this all has to do with at what time after conception the egg separates...an early split will form two placentas, two chorion, and two amnion...a middle of the road split will cause one placenta, one chorion, and two amnion...a little later of a split will cause one placenta, one chorion, and one amnion (high risk occurence) and any later will cause conjoined twins....

Answer 2

They try not to tell you they are id unless they are mo-mo twins. and they also are not supposed to tell you they are fraternal because two placentas can fuse together to become one or the egg could have split early to have two placentas.

I had Mo-mo twins. But as a studying OB Its more then likely the two sacs to placentas means fraternal. you'll get a better idea when you find out the sex and then you have a much better idea at delivery. But your two can look alike and not be identical. The best way to know is by genetic testing and Mo-mo's. most identical twins share the placenta and have different sacs. Wither it be the different large sac and two small sacs or two sacs all together.

Never trust the Internet for your research. Your Dr is who you need to talk to and ask questions. Ask him his reasons for saying they are fat twins.. and ask him what the chance is that they are Id with different placentas. If you don't feel comfortable with your OB it's time to change. Even if your close to delivery you want an ob that will tell you what's happening the entire way and be able to trust them with split second decisions.

I hope that help a little bit

Answer 3

There is a common misunderstanding about this when it comes to identical twins. I'm a father of identical twins and they had separate sacs and separate placentas.

When it was discovered that we had twins with separate sacs, our first OB/GYN went into this long-winded explanation in front of the student doc about how this meant that there were definitely fraternal. He couldn't have been more wrong (as you note).

For those that aren't aware of the specifics, usually, with identical twins, an egg gets fertilized, attaches to the uterine wall, and THEN splits. So, there is a single attachment point to the uterus, single sac, single placenta, and so on.

That is not always the case, though. If the egg is fertilized, then splits PRIOR to attachment (within four days of development), then there will be two separate attachment points, two separate sacs, two placentas, etc.

There is also the possibility of one attachment point, one placenta, but two separate sacs.

We were clueless about this at first. Since it was a high-risk pregnancy, my wife had several ultrasounds prior to the delivery. We knew early on that there were two placentas and sacs. So, we assumed (with the help of her ob/gyn) that the girls were fraternal. One of the ultrasound doctors asked, "Did your amnio tell you if they were identical or not?" Which floored us. At first we thought maybe he wasn't paying attention to the clearly visible line between our girls, so we politely said, 'they're in two sacs'. He said, 'I know. I can see that. But that doesn't necessarily mean they are fraternal.' And he went on to explain the whole thing. In fact, up to a third of identical twins can have separate sacs.

It was too late to get the amnio tests redone, and we didn't care that much about it at the time since they could be safely tested later.

After they were born we had a DNA test done and it confirmed they are identical.

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Here's some of the technical jargon about identical twins, sacs, and placentas.

Identical twins can have the same or separate amniotic sacs. Depending on the stage at which the zygote divides, identical twins may share the same amnion (in which case they are known as monoamniotic) or not (diamniotic).

Identical twins can have the same or separate placentas. Diamniotic identical twins may share the same placenta (known as monochorionic) or not (dichorionic). All monoamniotic twins are monochorionic.

Therefore, there are three different types of identical (monozygotic) twins:

(same placenta, same sac) monochorionic-monoamniotic
(same placenta, separate sacs) monochorionic-diamniotic
(separate placentas, separate sacs) dichorionic-diamniotic

Answer 4

I think you are hung up on the term identical. Identical as in twins, means 1 sac, 2 or more babies in the case of multiples.

Identical as in looking alike, happens quite often. My godsons are fraternal twins that just happen to look identical, but that doesn't mean that they are. Not that it really matters, but even if you are having fraternal twins, as in a multiple birth with 1 baby for each sac, there is a very good chance that they may appear to be identical. After all, they are still brothers, sisters or brother and sister. There are even reported cases of one black twin and one white twin, in the cases of mixed race unions, that look identical with the only difference being their skin tone. There are also cases in which a mother has had sex with different races of men, and those twins looked quite similiar. Even in cases of singletons, the offspring can all look identical, even though born in different years! So don't blame the docter in this case.

Answer 5

I don't mean to sound rude, but why would you believe an internet site over so many professionals that have been educated for a decade in order to practice obstetrics?
Fraternal twins arise from two different eggs released during your cycle. Both happened to be fertilized and implanted---alas, two amniotic sacs and two placentas.
Identical twins arise from a single fertilized egg that splits into to individuals. Since they come from the same egg, they share the same amniotic sac and placenta. The only way identical twins could develop in separate sacs on different placentae would be if the egg split and half the cells migrated across the uterus to the opposite uterine wall. THAT IS AN IMPOSSIBILITY.

Answer 6

My answer is the same way that they siad that I wasn't due until July 04 and I had my baby in May, early May. And they same reason why they say my best friend is three months but yet her baby is moving in her stomach and anyone can see and feel it. THEY ARE HUMAN! They are bound to make mistake. However I have never heard of twins being in seperate sac's being identical but that may be something to do more research on or find a new Ob/Gyn for a second opinion.

Answer 7

Not necessarily... fraternal twins do always have their own sacs, but so do most identical twins. The fact that they are in seperate sacs is any no way a good indicator of whether or not they are identical or fraternal.

Answer 8

To my understanding... identical means one sac because it started as one egg and one sperm that split into two. Fraternal twins can still look alike, but at the genetic level there are differences. It may be the wording on the websites you've seen as well, trying to put things in laymens terms, but confusing someone who really understands what they are looking for....

Answer 9

Doctors were told information in medical school that is now outdated. Even using the terms identical and fraternal is now outdated. The field of medicine changes all the time and doctors don't always keep up. Don't make the doctors responsible for everything. As you can see you can do your own research. Cut them a break. They are not perfect. And yes, they should know.

Answer 10

I have a friend that had twin boys last year. They are so alike that no one can tell them apart. They look alike. At birth they were almost identical in size. But because they had seperate sacs, they were automatically fraternal. I think they had the babies DNA tested and it was discovered they were fraternal, but my lord those babies are identical!

Answer 11

If it's only 33% then you are definately more likely to have fraternal twins. Make sure that the website you are using is reputable. There is tons of information out there that seems good but is often misinformed. What is the big deal anyways? You're having twins either way.