Saturday 1 December 2018

Women Expecting Monochorionic Twins Need to be Aware of TTTS

I'm happy to share a guest post with you today, written by Kate Phillipa Clark, the founder of, a wonderful resource website for those expecting and parenting twins. In this artcile Kate talks about Twin to Twin Transfusion Syndrome, which can be a serious complication of having twins, who share a placenta. Whilst it's really improtant to educate yourself about this, I want to make clear that it is only a concern to you if your twins share a placenta, and even then it only affects about 8-10% of monochorionic pregnacnies (source), so there is no need to get unduly scared, just speak to your sonographer and doctor at your next appointment. 

Women pregnant with twins need to know their twins chorionicity. It’s extremely important to know whether or not you expect twins who share a placenta to be on the lookout for conditions like Twin to Twin Transfusion Syndrome (TTTS).

It might not be the first thing you think about when you learn that you’re expecting twins. But knowing chorionicity in twins is extremely important. Chorionicity relates to whether or not your twins share a placenta. Twins who share a placenta are called monochorionic twins. A sonographer determines chorionicity by using ultrasound at the dating scan during your first trimester. If you learn that you are carrying monochorionic twins, you’ll need to be monitored more often than with dichorionic twins. Dichorionic twins have separate placentas and are not at risk of the same conditions as monochorionic twins.

Complications only related to monochorionic twins
There are several twin pregnancy complications that are only associated with monochorionic twins due to the shared placenta. One of those is Twin to Twin Transfusion Syndrome (TTTS). The condition is caused by a complication of disproportionate blood supply in the placenta. There are blood vessels within and on the surface of the shared placenta connecting both twins. Usually, these vessels allow blood to flow evenly between the babies, but, in rare cases, the blood flow becomes unbalanced. The twins share blood circulation and the blood is transferred disproportionately from one twin to the other.

Monochorionic twins need to be referred to a MFM specialist
In mild TTTS cases you may be able to get by with aggressive monitoring whereas other cases require treatment. There are several stages of TTTS. Severe, progressive TTTS is associated with close to 100 percent mortality if left untreated. The outlook for twins who get laser surgery for TTTS is much better. It’s very important that your doctor is aware of the risks associated with expecting monochorionic twins, and that he or she refers you to a Maternal Fetal Medicine (MFM) specialist if there’s any reason for concern. This should also be the case if your doctor isn’t able to detect your twins chorionicity. Your MFM specialist will do a Doppler ultrasound to estimate blood flow through blood vessels in the placenta and umbilical cords. This is the best way to monitor whether or not you show signs of TTTS.

4 other signs that might indicate a TTTS issue:

- Rapid growth of the womb and a uterus that measures large for dates
- Abdominal pain, tightness and contractions
- Sudden increase in your body weight
- Swelling in the hands and legs

It’s important that you contact your midwife/doctor immediately if you experience signs that worry you. Severe TTTS can progress really quickly and intervention is crucial in those cases.
Read about other mothers TTTS experiences and find out how they coped with the condition.

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About the Author: Kate Phillipa Clark
Kate is a journalist writing about twins and their parents on She’s written a great deal about twin pregnancy, twin pregnancy complications, twin birth and premature twins. Kate graduated with a bachelor's degree in journalism and an Executive Master in Corporate Communication. For some years, she worked in the private sector, before launching About Twins in 2016. She’s an identical twin and so is her father.