TTTS: How a first-trimester ultrasound can save babies’ lives

It was my second pregnancy. We didn’t want to find out the gender, we were sure of the conception date (give or take a few days), and we weren’t interested in terminating the pregnancy if there were signs of special needs. These were the reasons I felt people went for ultrasounds in their first trimester. My doctor may have suggested other reasons, but certainly not in a way that I felt I needed to make an appointment.

I wish I had.

On Monday of my 19th week, I went for my first ultrasound. It was twins! On Tuesday, I got called into the maternal fetal unit. I thought this was something that happened to all women carrying multiples. It’s not. We were told our identical twin boys had developed Twin to Twin Transfusion Syndrome. One boy was given a 60-per-cent chance of survival without intervention. The other was given a 10-per-cent chance of being born.

TTTS is a disease of the placenta affecting twins. Mostly, it happens with identical twins, though not all identicals will develop it. It can also affect triplets and higher-order multiples. Generally, any babies sharing one placenta are at risk, though in rare cases it can also occur with two placentas. Abnormal blood vessels in the placenta allow the umbilical cords to connect, resulting in one twin taking blood and nutrients from the other. One twin suffers decreased blood flow and bladder activity, while the other twin’s heart is strained by the excess he consumes.

There are five stages of TTTS. Stage One – which can occur at various times within a pregnancy, not just in the early weeks – is often noticed when one twin develops a larger sac of amniotic fluid than the other. Although TTTS doesn’t always present within the first trimester, knowing you’re carrying multiples and whether or not they share a placenta will allow you and your medical team to make important decisions about ongoing monitoring. Early intervention can mean the difference between life and death.

If TTTS is present, treatment at Stage One might be non-invasive. The pregnancy is tracked, with specialist appointments likely every two weeks. Modified bed rest or a protein-specific diet might also be introduced.

Stages Two through Four are where things get complicated – and those complications and stages can change quickly.

We were Stage Three. Our donor twin had almost no amniotic fluid and almost no bladder function, at 19 weeks. He was measuring about two weeks behind his brother in growth. Our recipient had dangerously high amounts of amniotic fluid, though thankfully was not showing any signs of cardiac complications. We were told to book a flight to Toronto; the surgeons at Mount Sinai hospital were ready for us.

In Canada, roughly 250 sets of twins each year develop TTTS, or about 15% of multiple pregnancies. Those who need intervention almost exclusively end up meeting the team at the Special Pregnancy Program at Mount Sinai Hospital. For just over 15 years, Dr. Greg Ryan and his team have been performing in-utero laser surgeries that can cauterize the connections made by the umbilical cords.

Before this surgery was available, treatment options involved drawing fluid from the amniotic sac multiple times; amnioreductions are still sometimes part of TTTS treatment, but it does not address the underlying issue of unbalanced blood flow between babies.

The survival rate for TTTS babies increased to 80 per cent from 10 per cent with the introduction of laser surgeries.

We’re among the many families who owe their children’s lives to the work done by Dr. Ryan and his team. We arrived in Toronto on Wednesday and were assessed that afternoon. On Thursday morning, my husband and I watched on an overhead screen as Dr. Rory Windrim and Dr. Ryan made a small incision through my abdomen and uterus and cauterized 17 places where the twins’ cords were connecting. On Friday, our donor baby was already showing signs of improvement – his bladder was once again visible! – and we were discharged.

Dr. Windrim told us that the average delivery for “laser twins” was 32 weeks. We made it to 32 weeks, 2 days. Alasdair and Rory arrived, kicking and screaming, and spent a few weeks growing in the NNICU before coming home. We were one of the lucky families.

Many TTTS cases reach Stage Five: the death of one or both babies. Researchers believe that many more TTTS pregnancies end in miscarriage, but because there wasn’t an early ultrasound, it’s unproven that this was the cause. Some TTTS pregnancies are terminated because of the condition; selective reduction may also offered as a treatment option when one twin is severely compromised. Sacrificing one twin can stop the syndrome, prolong the pregnancy, and improve the outcomes for the surviving twin.

As things stand today, there’s no way to prevent TTTS. No one has a crystal ball that can predict when an umbilical cord twinning event will occur, at how many points the cords will connect, or why one set of identical twins will suffer with it and another won’t. It’s not hereditary or genetic, it’s not caused by anything parents did or did not do.

But if more people knew about it, if more pregnant women were screened during their first trimester, perhaps more babies could be saved by intervention. My twins were lucky; if I’d missed that ultrasound at 19 weeks, even by another day or two, I’m not sure they’d be here today.

I didn’t know to ask for my boys. Please, make sure you and the women in your life know. Accept – or request – an early ultrasound. If there are multiples, ask how many placentas. If there’s one, get referred to a specialist familiar enough with TTTS to know the warning signs. It could save lives.

December 7: World TTTS Awareness Day


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