TAPS and Twins. What is it? How is it Diagnosed? What are the Effects of TAPS and Twins?

twins and TAPS

Author: Stephanie Ernst 

What is TAPS?

TAPS is a rare disease affecting twins sharing a placenta. There’s a lot of myths and misconceptions out there about it, which is something I want to try and “bust” for Twinfo readers!

As a TAPS mum myself, I know how scary and confusing this diagnosis can be. So I wanted to help you understand our disease and what is and isn’t true about it.

TAPS is Rare

Twin Anemia Polycythemia Sequence is a rare disease affecting twins who share a placenta.  (Note:  We say twins who share a placenta because TAPS *has* been recorded in non-identical twins. It’s rare, but it has happened in some cases of fused placentas – which is why it’s important to say a shared placenta).

There are 2 forms of TAPS – the “more” common form is spontaneous TAPS, which happens in around 3-5% of monochorionic twin pregnancies.  The second type happens after laser surgery for twin-to-twin transfusion syndrome, where connections in the placenta are not sealed properly or are missed on the edges of the placenta.

It’s caused by tiny connections in the placenta, less than a millimetre thick.  Unlike TTTS, which can be rapid and happen in hours and days, TAPS is a long, slow transfer of red blood cells from the donor twin to the recipient.  This causes the donor twin to become anemic with blood like a rosé wine, and the recipient twin with blood as thick as tomato sauce. 

The anemia can cause some problems with the donor twin, like heart failure, and contribute to them not growing as well as their sibling.  For recipient twins, their blood is so thick that it can cause problems for their hearts pumping it around. It can also lead to blood clots, causing severe problems like in-utero strokes and loss of limbs.

TAPS and Twins placenta

How is TAPS Diagnosed?

TAPS is diagnosed 2 ways.

TAPS and Twins – Diagnosis before Birth

Before birth, this is using doppler readings on the mid-cerebral artery in the brain. It’s like a speeding test on the brain – soundwaves are bounced off the blood as it moves through the brain. If it’s moving too fast, this can be a sign of anemia and too slow, a sign of polycythemia. 

These measurements are checked carefully (they should be checking them 3 times and taking the middle reading) and compared to each other. TAPS is diagnosed on the difference between the readings. If one is moving too fast and the other too slow, this can indicate that TAPS is developing.  Remember that just like a speeding camera, the readings depend on the operator’s skill and getting the right angle. If you have one lousy reading, it’s a good idea to go back and get checked in 2-3 days to confirm the diagnosis.  

It’s important to remember that there are other signs of TAPS on ultrasound as well.  Your team should also be looking for these.  Things like a bright appearance (echogenic) to the donor’s side of the placenta or an enlarged heart in the donor indicate TAPS.  Recipients can also have something called a “starry sky” liver. 

Even though there are other TAPS signs, you do need to have MCA dopplers done every 2 weeks, starting no later than 20 weeks.  These are still the most reliable way to detect TAPS in utero.

TAPS and Twins – Diagnosis after Birth

After birth, TAPS is diagnosed through blood testing, where they check the number of reticulocytes (or young, mature red blood cells). TAPS donors have high numbers of these, as their bone marrow is constantly creating red blood cells to compensate for all the ones they’re sending to their sibling. They’re also going to have low haemoglobin, meaning they may need some transfusions to kickstart their own red cell production.

Recipient twins might also need to have a procedure done called a partial exchange transfusion, where they will thin out the baby’s blood with saline, and take some out. 

twins and TAPS

Short And Long Term Effects of TAPS

One of the important things to remember is that both forms of TAPS have different outcomes, but that’s why it’s so important to screen for it. 

Post-laser TAPS has a higher rate of mortality for donor twins before, and just after birth.  However, long term effects are very similar to TTTS cases, with donors and recipients equally impacted. 

But spontaneous TAPS is very different.  The long-term effects of spontaneous TAPS are quite shocking, with donors at risk of a specific type of deafness (around a 15% chance) and are 4 times more likely than recipients to have some form of cognitive delay.

This is why we advocate so hard for routine screening for TAPS and twins.  Early intervention is vital, and there are treatment options available for TAPS patients.

The TAPS Support Foundation

So now, why is there a foundation for TAPS? Back in 2013, when I was diagnosed with TAPS, there wasn’t a lot of information out there about it.  A couple of journal articles, and a Wikipedia page, and really that was it.

Over the years it’s been hard to find a community that understood our TAPS diagnosis, and many doctors failed to recognise it as a different disease to TTTS.  There’s still a myth out there that it’s a form of TTTS, (it’s not!) and this means that some doctors will not take it seriously or do followup testing.

twins and taps
The TAPS Support Foundation

The TAPS Support Foundation

We started the TAPS Support Foundation to help raise awareness of TAPS, but also to help fund research into it.  In 2021, we’ve taken on our biggest project yet and are trying to raise the money to help put a part time TAPS researcher on at a university for 12 months. 

Because of our close association with researchers, we also have access to the latest research as it happens, and we even do some writing ourselves to raise awareness of the complications of twins!

We also provide open access resources on our website TAPSSupport.com.  And we do have a Facebook group, which is open to researchers, doctors, families and caregivers who either had, or think they may have had a TAPS diagnosis.  We call it our family, because it’s a place where you can go where everyone had been down a similar path, and understands the frustration of the diagnosis.

If you’re facing a TAPS diagnosis, or you want to learn more – get in touch with us! We’re here to help you navigate that diagnosis, and advocate for care before and after birth. 


stephanie Ernst TAPS twins

Stephanie Ernst is a freelance writer and self-proclaimed TAPS Nerd. She’s the TAPS Support Foundation‘s founder and spends her free time raising awareness of the issues facing parents of twins.  Her own experience with Twin Anemia Polycythemia Sequence (TAPS) and feeling the isolation of this diagnosis drives her determination to change screening protocols worldwide, support twin research, and raise the profile of multiples’ rights.

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