Twin to Twin Transfusion Syndrome (TTTS)

Twin to twin transfusion syndrome, or TTTS, is a serious condition that can occur in babies that share a placenta in the womb (identical twins or higher order multiples). TTTS occurs when the shared placenta contains abnormal blood vessels that connect the umbilical cords and circulation of the fetuses. The placenta may also be shared unequally (for example, one twin has access to ¾ of the placenta and the other only ¼) and one twin may not receive the necessary nutrients to grow normally.

When the blood vessels become abnormally connected, one baby (the recipient) may receive too much blood flow, while the other (the donor twin) does not receive enough. The donor twin may experience slower than normal growth, have poor urinary output and little to know amniotic fluid. Too much blood flow to the recipient can put strain on the heart, potentially causing heart failure. The recipient might have a more active bladder causing greater amounts of amniotic fluid.

TTTS can occur at any time during pregnancy, but is considered more serious between 12-26 weeks gestation because the babies are too young to be delivered safely. However, thanks to advances in science there are some treatments available to help twins with TTTS.

TTTS1bl

First of all, mothers of twins with a shared placenta should be monitored heavily by a Maternal Fetal Medicine (MFM) clinic. Ultrasounds should be performed biweekly to check on things such as amniotic fluid levels, blood flow in the placenta, visible bladders, size differences, etc. All of these can be indicators of TTTS.

If TTTS is detected, there are now treatment options (before, TTTS usually claimed the lives of both babies).

  1. Delivery of the babies – this will obviously need to be later in gestation, at a date when the babies are viable and their lungs have matured enough.
  2. Amniocentesis to drain excess amniotic fluid. This can improve the blood flow in the placenta and reduce the risk of preterm labor.
  3. Laser surgery to seal off the connection between the blood vessels. Laser surgery is often preferred to amniocentesis because it only needs to be done once. Amniocentesis may need to be done repeatedly to maintain proper blood flow. Laser surgery has an 80-65% survival rate of at least one twin, 65-70% overall twin survival, and 5% or less significant handicap rates in survivors.

Below is a video to help you better understand TTTS.

http://www.nbcnews.com/video/doctor-explains-ttts-twin-to-twin-transfusion-syndrome-581592643543

 

What type of twins are you having?

This is a question I get a lot lately from those familiar with carrying multiples. Had you asked me this question 4 months ago, I would have assumed the only answer was fraternal vs. identical twins. While those are the two major classifications for twins, there are actually various “types of twins” dependent upon if the pregnancy is a result of two embryos implanting, or one embryo splitting and implanting. Bear in mind, I am by no means an expert in this area and most of this information I have collected through my MFM visits and twins forums/boards.

Identical vs. Fraternal Twins

Identical vs. fraternal twins refers to zygosity, or one egg/one sperm vs. two eggs/two sperm.

Identical twins come from a single egg that has been fertilized by one sperm, and then splits into two separate embryos early in development. Both of those embryos implant and develop into a positive pregnancy test. They will have the same DNA, and look exactly alike, because they came from ONE embryo. Identical twins will always be the same sex – either boy/boy or girl/girl.

Fraternal twins develop when two eggs are fertilized by two separate sperms, and both implant. Fraternal twins can look a lot alike, but will often be easier to tell apart than identical twins. Their DNA is different. There can be boy/boy, girl/girl, or boy/girl sets.

 

Di/di, mo/di, mo/mo, & conjoined twins

Zygosity  (identical vs. fraternal twins), really has little impact on the treatment and prognosis of the twin pregnancy. What needs to be considered is chorionicity and amnionicity, or the number of placentas and the number of amniotic sacs that are present.

Chorionic = Placenta

Amniotic = Amniotic Sac

The image below can be helpful along with the following explanations of “types” of twins.

typesoftwins

Dichorionic/Diamniotic (di/di) Twins

Two separate placentas and two separate amniotic sacs (one for each baby). These are the most common type of twins and have the lowest associated risk. Fraternal twins are di/di. Some identical twins can be di/di if the embryo splits VERY early.

 

Monochorionic/Diamniotic (mo/di) Twins – what we are having!

Mo/di twins are identical and share a placenta but each baby has their own amniotic sac. These twins are more risky than di/di because of the shared placenta. A shared placenta is just that – shared. Sharing does not translate to equal. Mo/di twins are at risk for twin-to-twin transfusion syndrome (TTTS).This occurs when the blood vessels in the shared placenta are connected. This can result in one baby receiving more blood flow (the recipient) and the other receives too little blood (the donor). In the past, TTTS often had devastating results, but with proper monitoring and medical intervention, twins with TTTS now have a better chance of survival. TTTS occurs in approximately 15% of identical twins. More about TTTS will be covered in my next blog!

 

Monochorionic/Monoamniotic (mo/mo) Twins)

The least common and most risky, mo/mo twins share a placenta AND an amniotic sac. They are always identical. Mo/mo twins are at risk for TTTS and are also at risk for issues resulting from sharing the same amniotic sac. Because both babies are in the same sac, there is a chance their umbilical cords may become entangles or compressed, which can lead to one or both babies not receiving enough nutrients. Moms of mo/mo twins often end up in the hospital during the later second half of their pregnancy for bed rest and inpatient monitoring (multiple ultrasounds a week) to ensure the cords are not becoming tangled. At our first ultrasound we thought we were having mo/mo twins, but it was later confirmed that there was a thin membrane separating the amniotic sac into two.

 

Conjoined Twins

Conjoined twins are also identical, and occur when the egg does not completely separate into two embryos in the womb. They can share organs, tissue and/or limbs. Conjoined twins also share a placenta and an amniotic sac. I am not sure what their risks are for TTTS or cord entanglement.

 

I am currently carrying, identical, mo/di twin girls. Because of the risks associated with mo/di twins, I see a Maternal Fetal Medicine (MFM) specialist for regular ultrasounds, along with my OB. Having twins is scary, and having mo/di twins is even scarier. We are trying to take things one day at a time and continue to pray for a healthy pregnancy and delivery.

Bump envy

Come ON baby bump, where the heck are you?! Just this past week I have started to notice a small little bump in my abdomen. And none of my pants button anymore. Sounds normal for a woman almost 16 weeks pregnant, right? But what about a woman pregnant with twins? I feel like I should be so much bigger by now!
To the average street walker, I would just look like I had recently stuffed my face (which I probably did) and am letting myself go a bit. Unless I have on a tight top, there really isn’t much to see. Every time I see another pregnant woman with a belly bigger than mine I get jealous. Especially because the past week I have started to feel normal again. I want to LOOK pregnant. I want people to come up to me at the grocery store and ask me when I am due. I want to eat all of the bag French fries before we get home without looking like a hog (I know my husband knows I’m pregnant, but what about the person next to us at the stoplight?). I want my belly button to pop out.

  
I am a member of several Moms of Multiples/Twins forums, boards and Facebook group. Everyone, and I mean EVERYONE, looks bigger than me at this stage. On top of the not looking very pregnant, it also makes me worry that my babies aren’t growing! I haven’t had an ultrasound in almost three weeks, so I really have no idea what is going on in there.
I just want a bump. A big round bump to rub lotion on, to rest my ice cream bowl on, and to dress really cute. Is that too much to ask?