Please note that
as of June 1st, 2003 the Randomized Controlled Trial has been completed.
Interim analysis showed sufficient patient recruitment. Data are being analysed
and will be published in due time in the peer reviewed literature.
Syndrome (TTTS) is a severe complication occurring in monochorionic (identical)
twin pregnancies. If left untreated, the mortality is very high and fetuses
will die in utero or after birth in most cases. Early diagnosis and treatment
are essential for improving the poor prognosis of these pregnancies. There
are at present mainly two established options for the treatment of the
syndrome, but it is not clearly established which is the best, which raises
the need for further evaluation.
What is Twin-to-Twin Transfusion Syndrome
TTTS occurs in 10% to 15% of identical twins. One fetus is passing blood to the other over
abnormal connecting vessels in their shared placenta. These connections are normally
existing in most identical twins but, in a small proportion of these pregnancies, and due
to unknown reasons, connecting vessels lead to TTS. Therefore, the fetuses are normal but
there is a problem in the placenta.
Consequences of TTTS
In advanced cases the fetus who is transfusing (the donor) does not get enough blood and
develops severe anemia, and the transfused fetus (the recipient) gets too much blood and
its heart must work over its capacity, which eventually leads to heart failure. The
prognosis for both fetuses is extremely poor, and the mortality in utero ranges from 60%
to 100%, with almost one third of survivors presenting with severe complications after
Diagnosis of TTTS
The TTS is detected by ultrasound examination. The donor fetus is frequently smaller in
size than the recipient and there is very little fluid in its amniotic sac. The recipient
fetus is usually larger and passing more urine, which causes an excessive amount of fluid
in its amniotic sac.
Treatment options for
consists in performing amniocentesis (inserting a needle into the gestational sac), once
or as frequently as required, to eliminate excessive fluid. The average survival achieved
by amniodrainge is about 60 %, but neurodevelopmental impairment has been described to be
around 20% of surviving infants.
A more recent development is fetoscopic
laser surgery. Direct vision of the placenta is achieved through an endoscope, and the
communicating vessels are identified and destroyed with a laser. Experience with over 300
cases gives a survival rate of 55 % to 60 %, with at least one survivor in 75-80 % of
pregnancies. Neurological damage in surviving infants at one year of age is around 5 %.
The Eurofoetus programme is
conducting two main activities in the field of TTS open to participation of all centers
preferentially via the Internet:
The Twin-Twin Transfusion Syndrome Randomized Trial
Observational Study on TTS