sMater | Dr Glenn Gardener | Part 1 - Twin to Twin Transfusion Syndrome

The first of a three-part series featuring maternal fetal medicine specialist, Dr Glenn Gardener, this episode explores diagnosis and treatment of Twin to Twin Transfusion Syndrome.

TTTS affects identical twins who share a placenta and carries a high risk of fetal death if left untreated.

Dr Gardener, Director of the Mater Centre for Maternal Fetal Medicine, discusses diagnosis, treatments and patient outcomes, as well as the role of GPs in providing shared care of mothers.

GP Education activity log:

• Podcast title - sMater: Twin to Twin Transfusion Syndrome
• Provider - Mater Misericordiae Ltd Date published - February 7, 2025
• Certificate of completion - click here

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00:00 - Introduction

01:35 - Diagnosis of TTTS

3:30 - Dangers of TTTS

06:08 - Treatment of TTTS

09:20 - Questions from GPs

14:43 - The future of TTTS

15:40 - The Check Up

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#TTTS #twinpregnancy #pregnancyhealth #healtheducation #smater #mater

To learn more about Mater, visit https://www.mater.org.au/

Transcript

Hello and welcome to this episode of sMater. A podcast by clinicians for clinicians brought to you by Mater, an Australian leader in healthcare for more than a century. My name is Jillian Whiting and we're coming to you from Meanjin the land on which this podcast is being recorded.

In this three-part miniseries we're talking about in-utero surgery with Dr Glenn Gardner a Maternal Fetal Medicine specialist and Director of the Mater Center for Maternal Fetal Medicine at Mater Mother's Hospitals.
This episode is about Twin to Twin Transfusion Syndrome. A condition that affects about 1 in 10 identical twins that share a single placenta.

We are Mater. We are Mater. We are Mater. This is sMater.

Hi Glenn. Welcome to sMater. Thanks for having me. Glenn, first of all what is Twin to Twin transfusion Syndrome? So Twin to Twin Transfusion Syndrome which is quite a mouthful or TTTS as we like to call it is a condition that only affects twins that share a placenta and the underlying problem is that they have blood vessels that connect between the umbilical cords where one baby is pumping blood into the other baby and that those connections are unbalanced so one baby has a lot lot more urine output gets excess fluid the other baby has less urine output and has less fluid and that really describes the kind of the condition as it presents to us clinically. It's associated with a high risk of the baby's dying if it's not treated.

Okay how is Twin to Twin Transfusion Syndrome diagnosed and what are the signs that primary carers should keep an eye out for?

So Twin to Twin transfusion Syndrome and I might just shorten that to TTTS because it's a bit easier so TTTS is usually diagnosed by ultrasound but actually women may present before the ultrasound with symptoms and the most common symptom would be that their tummy getting big rapidly over a short period of time. Well first of all they've got twins now it' be nice to to think that all women know they have twins at an early stage in pregnancy but that's you know across you know rural and remote regions that's not always the case so anyone who presents with a positive pregnancy test and their tummy is getting big, one of the first things I'd want to know is do they have twins and could this be TTTS and so that excess fluid is one of the key symptoms and how are you testing well screening to the excess fluid so if we go back a step if we know someone has twins from an early stage. A lot of people have an early dating scan and we diagnose twins and the type of twins is really important so the two commonest groups of twins that we like to categorize are monochorionic twins that share a placenta but are in separate sacks and dichorionic twins that have two separate placentas and two separate sacks. Now dichorionic twins behave generally like singletons they're at increased risk of pre-term birth but monochorionic twins have all these other complications that are possible not in every case but they're much higher risk because they share a placenta and so from an early stage if we know someone has monochorionic 

twins they should have fortnightly scans and those two weekly scans can give us an early heads up that one of those complications of a shared placenta is actually happening and then they would get referred to us.

Which twin is TTTS
more dangerous for, the donor twin or the recipient twin and why?

So it's a very good question. It could be either it could be both or it could be either. Generally TTTS can sometimes get mixed up with twins of a different size and that's a different problem so twins that share a placenta don't always share the placenta equally so one might be bigger or normal size the other one might be really small because it's not evenly shared. Now that's not TTTS and we get a lot of referrals because of the size difference saying could this be TTTS it's actually about placental share so in those cases there isn't really a donor and a recipient but if we go back to the scenario of TTTS where a recipient receiving blood from the donor is pouring out much more urine and has a lot more fluid and the other one has less fluid they're both at risk so the recipient at risk of heart failure from overload being having too much fluid and the donor is at risk from having too little fluid and renal kind of impairment.

If one of the twins does die what is the impact for the surviving twin?

That's really important because they share a placenta and invariably these twins will have connections on blood vessel connections on the surface of the placenta. If one twin dies then the blood pressure in that twin drops dramatically and blood from the surviving twin can flow unvetted

across the placenta to the point where that twin that might might have been able to survive could either die also or suffer lack of oxygen to the brain and then have permanent brain injury. That occurs about 30% of the time if one twin dies so that's death or disability and about 2/3 or 70% the surviving twin will be okay so and we can do some tests to find out if the surviving twin is going to fair okay.

Can TTTS also occur in 
multiple pregnancies like triplets and quadruple?

Yeah so it does relate to whether there's a shared placenta. Now we looked after triplets where all three fetuses share one placenta and there can be this three-way sharing of blood vessels on the surface of the placenta and they can get it's you know Triplet to Triplet Transfusion Syndrome.

It's very rare. Most triplets that we see will have a monochronic pair plus a singleton as the set. The singleton is not connected but the other two that sharing a placenta can get Twin to Twin transfusion syndrome and it's important I guess at this point to talk about the treatment options then for TTTS so over the years the treatment options were largely driven by the excess fluid in the recipient sack to reduce that because then you're going to reduce the risk of ruptured membranes and pre-term birth. Later on an important discovery in the US was that if you introduced an instrument that could laser the blood vessels between the twins on the surface of the placenta you could really stop the underlying cause of the of the condition and um and we adopted that approach back in 2002 we did the first laser in Australia and since then we've been the busiest unit in the country. We do about 20 to 24 lasers a year for TTTS and our counterpart's interstate would do somewhere between kind of you know 8 to 15 just to give you an example of our 
I guess exposure to the condition and they're not always straightforward sometimes they're very straightforward where we would expect survival to be in the order of you know 3/4 of baby surviving after the laser if you compare that if you don't treat the rate of loss is somewhere in the order of 80 to 90% of babies won't survive without treatment so if you can convert that to overall 75% survival it's pretty dramatic like in terms of you know the effect of laser surgery. You talked about some of the complications  can you explain a little bit more? Unfortunately we can't get away without some risk when we put an instrument in through the wall of the uterus and operate in utero on the placenta the biggest risks are ruptured membranes and pre-term birth. On average we would get 10 weeks after a lasered before delivery and when I say on average you know some patients will go near to term and others will go even earlier so that's always discussed very carefully with with parents before we undertake um the procedure but you know when you balance like what the alternative is of not treating it's a pretty it's it's a no-brainer about kind of what the approach should be.

Can you also step us through that laser surgery and the time, what happens during that procedure?

So once we've made the diagnosis and we've done the counseling and parents have chosen to proceed we would do the procedure the laser surgery in theater but they don't have a general anesthetic they just have some sedation and so they're awake and they can actually even watch the procedure if they want to and they're comfortable local anesthetic on the skin it's a single 3.5 3.8 mm little instrument that goes in through the wall of the uterus and through that we can do everything we can I can visualize the placenta that's projected onto a big screen and I can introduce a laser fiber and laser vessels that I carefully select that are the vessels in that are causing the problem. I don't want to kind of laser any vessel because I want to leave obviously the rest of the vessels for the babies to grow and thrive on after the laser.

There's so much interest in the work that you're doing so we've asked a number of GPs to submit some specific questions to you. Okay Glenn can you please explain the difference between DCDA, MCDA and MCMA twins and how that influences the risk of Twin to Twin transfusion syndrome? Is monitoring different depending on the type of multiple pregnancy? Yeah great question and yes it is very different.  So we'll start with DCDA twins which is about accounts for two thirds of twin pregnancies the most common type and a lot of people will think DCDA twins are the non-identical twins and mostly they are but there can sometimes be identical twins amongst those DCDA twins. The important thing is they don't share a placenta so they're not really going to harm each other in utero and hence we don't need the same level of surveillance so it's more about growth and well-being every four to six weeks. Generally for DCDA twins. Monochorionic or MCDA twins where they share a placenta are the ones at risk of Twin to Twin transfusion syndrome although they share a placenta they actually still have their own sack. That's the diamniotic bit they're monochorionic but diamniotic and that's the bit that the monochorionic bit is the bit that says they have mono one placenta. Now monochorionic mono amniotic is different again and much rarer that's where both twins are in the same sack and share the same placenta. Interestingly whilst you might say well they they also are at risk of Twin to Twin Transfusion Syndrome they hardly ever get it and that's why we believe that's because their cord insertions into that placenta are very close together and they have a lot of connections that are balanced so they tend to sort it out. They're at risk of cord entanglement though which is a different problem the others are not at risk of that and we monitor them very carefully because if they get entangled they can die suddenly without our ability to intervene so we monitor them monitor them at least fortnightly and then we tend to deliver them early because because we won't tolerate when they could survive the the tragic loss due to cord entanglement.

Another question from one of our GPs when a patient is referred to MFM what is the process like? If my patient is coming to um MFM for the first time for example after an abnormality is found on a scan in the community what can she expect to happen who will she see on the day and will she have counseling and are those results communicated back to me and the rest of the team? Lots in there.
Yeah it's a great question because really some people don't know what we do and we we're a multi disciplinary service and the point of that is that we want patients that are referred to us to try and have everything covered not have to go to see different people and so we have expert Maternal Fetal Medicine sonographers so they're just operating at a obstetric ultrasound level that is different to a general sonographer. They're  technical people doing the Imaging we have Maternal Fetal Medicine Specialists like myself that actually are then interpreting the images and counseling the patients and doing procedures. We have midwives that special trained in maternal fetal medicine that provides support and ongoing support through the rest of the pregnancy and of course our admin staff that kind of pull it all together to make sure that patients are informed of their appointments and when they need to be there. We also have social work neonatal that that come in as needed but there are our four core specialties so when a patient comes to see us they will have an ultrasound they will see a Maternal Fetal Medicine specialist they will then often have uh contact with one of our midwives and as required that report would be fed back to the referring doctor and we always make sure the patient also gets a copy and sometimes it requires a second visit because there's a lot of information in a single visit that often requires you know within a short time frame to get them back to just go over things it's a lot to take in it's we of course work very hard to describe everything in terms that they can understand it's not a lot of there has to be some medical terms but we don't want to overload them with information that is 

really you know at a medical it has to be really explained in a way that they can understand it.

It would be a lot for a patient a woman to digest which goes to the next question as a GP well how do I best support my patients who have those complex fetal issues diagnosed in pregnancy? Yeah I mean some parents feel that you know why wasn't this picked up and and so we we explained very carefully that this is a very specialized area we would have no expectations of diagnosis or treatment options being provided at a GP level so the support that we have an expectation on from a general practice is that they know the woman better than we do they've they've sometimes cared for these patients for years and so that that kind of level of support that is ongoing once they've left our care is very important and they can still have great concerns about that outcome of the pregnancy um and so regular ongoing support touching base with the patient making sure that all the other things of pregnancy care are attended to is very important.

What do you see ahead in the future for research in TTTS so there's been certainly you know a lot of change over the last 20 years we've modified the procedure to make it safer. The likelihood that that that we'd have to do it again is reduced to less than 1%  whereas previously it was as high as 10% so there been remarkable gains already the future probably is in miniaturization of the equipment. We're a little bit shackled by the ability to project an image from a very very small you know tube because you have to get a lot of information out of that so fiber optics is is constantly improving and the ability to miniaturize means you're making a smaller hole in the membranes and and and so for us as we get our instruments smaller we hope that we're reducing the risk of the procedure. And finally Glenn three quick questions and this is to give everyone listening an insight into to Glenn when he's not at work. Okay how do you relax away from work?  I love tinkering I'm a bit of a I mean I kind of like pulling things apart and tinkering around. With things electrical equipment or anything that moves? Anything. Kind of grew up you know restored an old kind of car once when I was younger and now I have an old boat that I like to tinker with. Goes to my next question which you may have just answered is do you have a secret talent?
Actually I think yeah it's kind of how my career has evolved into doing kind of fetal therapy within Maternal Fetal Medicine I think has been based around the fact that even before I did this specialty I was interested in in how things worked and how things can be fixed so I think that has kind of really helped my career and I think you know having good hand eye coordination it helps as well so it would. Finally what words of wisdom would you have for a junior med student just starting out? I would say look don't expect that you're going to know exactly what you want to do from the get-go you can find your path and you know a lot of people want to know where they're going to be very early and it feels very competitive but it'll come to you know your passion will be lit by some of those jobs that you do and follow that path and that will lead you to a career that kind of you know the old saying that coming to work is actually not like work. Glenn thanks so much for your time. My pleasure. 
For our listeners at home or in the car or having a well-deserved break between patients, thanks for tuning in and see you next time on sMater.