FAQ
How does this research aim to save twin lives/what is the purpose of this registry?
The TTTS registry aims to record all complicated monochorionic and dichorionic multiple pregnancies in the UK, their treatments, and outcomes. The registry also records natural history of uncomplicated monochorionic twins and triplets. The UK registry will provide a tool to improve clinical practice and therefore patient care. As well as monitoring the birth outcomes of TTTS, the database will also help monitor the survival rate and neurodevelopmental outcomes of the condition, which are currently unknown. - How will doctors and patients record their experience on the database?
The database will be available on a secure, web-based, data entry system. Patient’s personal information will be kept confidential. Professionals will be able to compile their experiences on this database by answering a series of standardised questions. The registry will be managed by a committee which consists of the relevant stakeholders, including all those involved in the diagnosis and management of twin pregnancies complicated by TTTS (i.e. patient representatives, healthcare providers, Royal College of Obstetricians and Gynaecologists, and British Maternal and Fetal Medicine Society).
- Has there ever been a TTTS registry before?
This will be the first TTTS registry in the United Kingdom and the first online registry anywhere in the world.
- What percentage of TTTS survivors are disabled?
Unfortunately, currently a significant proportion of TTTS survivors are disabled or suffer from long-term health problems.
- How will the registry work?
The registry will be managed by a committee consisting of the relevant stakeholders, including all those involved in the diagnosis and management of twin pregnancies complicated by TTTS. That is, patient representatives, healthcare providers, and government representatives, Royal College of Obstetricians and Gynaecologists, British Maternal and Fetal Medicine Society. The registry committee is responsible for determining how and in what form the data will be managed and used.
- Who can access the registry?
Only nominated, and security cleared representatives from the participating centres can access the registry. They are limited to accessing the data from their own centre. Permission must be sought and granted to gain more detailed access to records beyond individual centres.
- Can patients access the registry?
At this stage, there are no plans to allow patients to access the registry. Twins Trust is always keen to gather patient feedback and you can email them at tttsregistry@stgeorges.nhs.uk .
How will you get medical professionals on board?
Healthcare professionals will be encouraged to enter data into the registry by the consensus group which manages the database. The consensus group consists of the relevant stakeholders, including all those involved in the diagnosis and management of twin pregnancies complicated by TTTS (i.e. patient representatives, healthcare providers, and government representatives, Royal College of Obstetricians and Gynaecologists, British Maternal and Fetal Medicine Society). - How many babies die of TTTS per year?
Currently, around 300 babies die of TTTS in the UK each year.
- What is TTTS?
Twin to Twin Transfusion Syndrome (TTTS) is a rare but life-threatening condition that affects 10 to 15 percent of identical twins that share a placenta (monochorionic twins). TTTS can also occur in triplet or higher order pregnancies with monochorionic twins. If untreated, 90 percent of babies are likely to die. Even with treatment, 50 percent of surviving babies are likely to be disabled or have a long term condition.
The blood vessels within and on the surface of the shared placenta connecting both twins should allow blood to flow evenly between the babies so that each baby receives the same amount. However, in TTTS, part of the blood flow is diverted from one ‘donor’ twin to the other ‘recipient’ twin in what is effectively a blood transfusion (hence the name).
A lack of blood supply can affect the donor twin’s growth so they are smaller than average. The recipient twin is usually larger and has a higher blood volume, which can strain their heart as it works harder to cope with the extra blood supply.
To compensate for the excess blood, the recipient twin often produces a large amount of fluid. In contrast, the smaller donor twin can become stuck against the uterus wall with little surrounding fluid.
- Who does TTTS affect?
TTTS only affects identical twins who share a placenta. TTTS can also occur in triplet or higher order pregnancies with monochorionic twins. They are referred to as monochorionic twins because they share an outer membrane (chorion) – the technical term is MCDA and MCMA twins.
- What are the treatment options?
If the TTTS is mild (Stage I), no treatment may be required and it is possible that the condition will remain stable or improve. The pregnancy will be closely monitored and if TTTS becomes more severe, the doctors may recommend intervention. The choice of treatment will depend upon the stage of TTTS and how many weeks pregnant the mother is.
There are three possible treatment options for TTTS:
• Amnioreduction - involves draining excess amniotic fluid from around the larger recipient twin.
• Laser ablation – this therapy involves finding every blood vessel connecting the twins and closing them to prevent the flow of blood from one baby to the other and the possible risk of transfusion.
• Selective feticide - In a few cases, the only way to prevent the loss of both twins is to close off the blood flow to the sick baby’s cord sadly meaning the baby will die in the womb.
References
1. Khalil A, Rodgers M, Baschat A, Bhide A, Gratacos E, Hecher K, et al. ISUOG Practice Guidelines: role of ultrasound in twin pregnancy. Ultrasound in Obstetrics & Gynecology. 2016;47(2):247–63.
2. Khalil A, Beune I, Hecher K, Wynia K, Ganzevoort W, Reed K, et al. Consensus definition and essential reporting parameters of selective fetal growth restriction in twin pregnancy: a Delphi procedure. Ultrasound in Obstetrics & Gynecology. 2019;53(1):47–54.
3. Kalafat E, Sebghati M, Thilaganathan B, Khalil A, Collaborative (STORK) the STOR. Predictive accuracy of Southwest Thames Obstetric Research Collaborative (STORK) chorionicity-specific twin growth charts for stillbirth: a validation study. Ultrasound in Obstetrics & Gynecology. 2019;53(2):193–9.
