Twin Anemia Polycythemia Sequence – A Rare Disease Affecting Twins

by | Sep 29, 2022 | Blog, Patient stories|Rare disease world

This week’s blog is written by Stephanie Ernst, Founder of TAPS Support. Stephanie shares her personal rare journey with her TAPS twins: Emilie (donor) and Mathilde (recipient), who were born in the Netherlands in 2013.

Emilie and Mathilde are the reason that TAPS Supports exists. Stephanie, Emilie and Mathilde’s story is just one of many TAPS stories out there. Theirs is one of the happy ones – and it’s all down to getting the right care and treatment.

Read their story now and share to spread Stephanie’s message of hope. Like Stephanie says:

“That’s why sharing our stories is important – we may all be rare – but we can shout loudly together.”

We all know how rare and unique twins can be – double trouble, a friend for life, a mini partner in crime – when we discovered that we were having identical twins, all these thoughts and more went through our heads.

(Of course, along with the shock and disbelief of Oh my god, we’re having twins! I mean, finding out you’re having twins can be a real shock to your system!)

Our twins were monochorionic, diamniotic – identical twins that share a placenta but have separate amniotic sacs. Because they shared a placenta, we were at increased risk of complications like Twin-Twin Transfusion Syndrome (TTTS).

Our local hospital was fantastic and explained the risks to us. They also explained that we would receive close monitoring, with appointments every 2 weeks, to ensure that our twins were growing well and there were no complications.

Things were progressing well, and I had a relatively complication-free pregnancy, even with some hiccups like severe morning sickness. At 20 weeks, we found out we were having girls and began preparing our lives as a future family of 4.

23 Weeks Pregnant

At 23 weeks, I began to feel like my belly was hard and really tight. I also had backache, which I put down to the fact that there were 2 babies in there, and they were growing. Of course, feeling a bit bigger and having a few aches and pains was normal with twins, right?

But this should have triggered my brain to go to the doctor.

At my 24-week checkup, there was a big difference between the amniotic fluid in my girls, and I was rushed to a specialist tertiary hospital to confirm a diagnosis of TTTS. While I was there, they also performed a second test. They saw signs of a second, newer, rarer diagnosis – Twin Anemia Polycythemia Sequence, or TAPS.

This was devastating, as both conditions are rare, and to be diagnosed with both in one day was terrifying. Treatment options were presented to us, but we were so overwhelmed with all the information that we opted to come back the following day to discuss our options.

It was honestly the most scared and vulnerable I’d ever felt. I found much information online about TTTS, but it conflicted with what my doctors told me. I could not find any info about TAPS that was easy to read – it was more of a subheading in some places, and all of it was either in medical journals or another language. This was confusing and scary.

The team I saw was reassuring, and I felt confident in their care. We opted to take the option of close monitoring every couple of days, and this saw things stay stable. Our TTTS diagnosis stabilised and eventually was dismissed as we were one of the rare cases where it resolved itself.

However, the suspicion of TAPS stayed and became our primary diagnosis.

What Is TAPS?

Twin Anemia Polycythemia Sequence is a rare disease affecting twins who share a placenta. (There are rare exceptions to this). It affects around 3-5% of these twins, but we don’t know how accurate this statistic is, as it is not routinely screened for worldwide.

TAPS is caused by tiny connections in the placenta, less than a millimetre thick. These connections go in one direction. The donor baby sends only red blood cells to their twin sibling, causing chronic anemia. The recipient baby’s blood becomes thick and difficult to pump around. This is called polycythemia.

Diagnosing TAPS is difficult. In TTTS, the fluid differences, as well as symptoms for the parent, such as feeling heavy, or big, or a tight feeling in the stomach, rapid weight gain, and a lack of movement from the babies. Ultrasound will show the significant differences between the fluids of the babies – with one baby having less than 2 centimetres of fluid and the other having excess fluid.

 (Note, staging TTTS has some controversy. While it’s generally accepted that more than 8 centimetres of fluid) in the recipient twin makes stage one (Quintero staging); across the UK and Europe, after 20 weeks, TTTS is sometimes diagnosed when the recipient has 10cm or more of fluid (Eurofetus trial). Neither are wrong; what matters is monitoring and treatments!)

This doesn’t happen in TAPS. TAPS doesn’t have fluid differences (but, like in my case, it can occur in parallel with TTTS). Instead, it is detected by doppler ultrasound on the brains of the developing baby. The speed blood travels through the mid-cerebral artery is tracked, and if it’s travelling too fast, this is a sign of anemia. Too slow means that the blood is too thick.

This test is controversial; unfortunately, many countries do not routinely screen for TAPS. The reason is that there is currently no best treatment for TAPS, so management options are unclear. However, there are treatment options available, like laser surgery (they draw a line across the placenta with a laser to stop any connections between the twins), inutero blood transfusions, early delivery, and, like me, a watch and wait approach is absolutely possible. TAPS moves slowly, so it’s possible to closely monitor it.

There is also the reason used that they’ll see signs on ultrasound. There are signs on ultrasound, but not always. MCA doppler is the most reliable and accurate way to detect TAPS.

The long-term effects of TAPS are also concerning. 1 in 8 donor twins is born profoundly deaf due to Auditory Neuropath Spectrum Disorder (ANSD), and donors are also four times more likely than recipients to have developmental and cognitive delays. Both twins are at risk of neurodevelopmental impairment. It’s a serious disease with severe long-term outcomes, so screening is essential.

Back To The Story

For the next 7 weeks, we were closely monitored by our team. They would look at the doppler at each appointment and establish that things were stable. It was a matter of watching and waiting to see what would happen next. Every 2 days, we’d go back to our incredible team to see that the news was stable.

At 30 weeks, I went for my regular checkup, and the news changed from stable to concerning. One of the rarer complications of polycythemia is that blood clots can form in the recipient. There were worrying signs on the ultrasound of the brain of my recipient, and the decision was made to deliver my girls.

2 days later, at 31 weeks, my girls were born, one pale and anemic, with blood like rosé wine, and the other dark red, with blood like treacle. Their condition was made stable with special blood transfusions and extractions, and they were in neonatology for the next 5-6 weeks.
Then my recipient came home, followed by her sister, the donor. The next few years are really a whirl of both the chaos of twins and the follow-up appointments we needed for prematurity.

At the time, no one could tell us our girls’ long-term outcomes, but we were reassured that as research continued, we’d be updated.

As our girls grew, we knew things weren’t quite going well with their development, and we repeatedly raised concerns. But we were always brushed off – it’s nothing to worry about.

The girls were around 5 years old when we received more information about TAPS’ long-term outcomes, and we started advocating for further testing. At age 7, they were diagnosed with autism and Developmental Coordination Disorder (DCD). We fell in line with the neurological outcomes for TAPS. Still, it took a lot of advocacy and pushing the system to get the diagnoses.

Starting a Foundation

Over the years, I connected with more and more families with similar stories to ours. I had also remained in touch with the research team that had cared for us. I realised that there was just not a lot of research into our disease and that funding for rare diseases is limited. I decided it was time to change this – at least for twins – and started a foundation to help fund more research into TAPS.

Since we started 2 years ago, we’ve successfully completed a few projects, funded research into donor twins at birth, and even presented on our incredible partnership with the research team who diagnosed me all those years ago at ECRD2022.

Much is needed in the world of rare diseases like TAPS. We need more awareness because no one thinks that something as unique as twins would be impacted so hard by rare diseases. We need to get routine screening and more funding for research. This isn’t a problem only for twins – I know all rare diseases need this.

That’s why sharing our stories is important – we may all be rare – but we can shout loudly together.


For more information on TAPS Support, visit