Twin to twin transfusion syndrome

I have an interest in complex twin pregnancies and have some information (probably more for health professionals) on a condition called Twin to twin transfusion syndrome. We are shortly starting a programme of laser treatment in Auckland. Follow the link to the Mercury Matters article from Mercury Energy who are supporting us through Starship Foundation in the Auckland MFM unit:

http://www.mercury.co.nz/Residential/news_story.aspx?id=1056

Twin to twin transfusion Syndrome (TTTS)
Twin pregnancy occurs in approximately 2% of pregnancies and the rate is increasing. This is thought to be due to increasing maternal age and increasing use of assisted reproductive technologies which are both known risk factors for multiple births. 1/3 of twin pregnancies are higher risk by virtue of having a single shared placenta (monochorionic placenta). It is estimated that 85% of all monochorionic placentas have anomalous vascular connections. Of these 15% have sufficient imbalance to produce Twin to Twin Transfusion Syndrome (TTTS). In this situation one twin receives more blood flow than the other by virtue of unidirectional flow along connecting vessels. This diagnosis carries an extremely poor prognosis and it can be responsible for up to 20% of all perinatal deaths in twins.
TTTS diagnosis peaks at 22-26 weeks gestation. This is one of the most ethically and medically challenging times of pregnancy as delivery at this time leads to poor outcomes.
The natural history of TTTS is associated with 80-100% mortality for both twins in the most severe cases. The most affected fetuses usually present with signs of TTTS before 20 weeks gestation. This is manifested with polyhydramnios/oligohydramnios (excess and reduced amniotic fluid), empty bladder/ full bladder, abnormal blood flow patterns within the two fetuses and heart failure. Stage 1 is where there is disparity between amniotic fluid volumes only. If there is any of the other features mentioned above the staging will be 2, 3 or 4 and considered severe. Treatment severe TTTS (stage 2, 3 or 4) is either serial amnioreduction or selective fetoscopic laser photocoagulation (SFLP).
Amnioreduction involves giving the woman a local anaesthetic into the anterior abdominal wall plus intravenous sedation if indicated. Following this, under aseptic conditions a large bore cannula (needle) is inserted into the amniotic fluid of the sac of the fetus with polyhydramnios under ultrasound guidance. After the needle is removed the cannula is attached to a wall suction unit and a volume of amniotic fluid is withdrawn. This usually takes around 1-2 hours. It is thought that the release of pressure on the placenta allows normal flow patterns to restore in the placenta, though the majority of women require repeat procedures.
SFLP involves giving the woman a local anaesthetic into the anterior abdominal wall plus intravenous sedation if indicated or rarely a general anaesthetic. Following this, under aseptic conditions an operating fetoscope of 3.2mm diameter is inserted into the uterine cavity under ultrasound guidance. The fetoscope is then used to identify the vascular connections along the placental surface and they coagulated individually using laser. This procedure effectively stops the process of TTTS by ‘separating’ the two fetus’s circulations within the placenta. Therefore only one procedure is performed.
A randomised controlled trial from the Eurofetus group (grade 1b evidence) comparing laser surgery with serial amnioreduction showed significant benefit in the laser group (1). It is the largest randomised controlled study to date. The laser group had a higher likelihood of survival of at least one twin to 28 days of age 76% vs. 56%. Infants in the laser group also had a lower incidence of cystic periventricular leukomalacia (6% vs. 14%, number needed to treat (NNT) 12.5 cases) and were more likely to be free of neurological complications at 6 months of age (52% vs. 31%). The presence of cystic periventricular leukomalacia has been shown to have a very high correlation with the development of cerebral palsy in the neonate. A meta-analysis has been performed of all randomised controlled trials (RCTs) published to date and confirms the findings of the Eurofetus study (2).
Follow-up studies of pregnancies treated with SFLP have shown that at two years of age the rates of major neurological abnormality are 6% and minor neurological abnormality are 7.2% (3). This suggests there is no hidden morbidity from the procedure not apparent in the initial randomised controlled trial and confirms the relationship between cystic periventricular leukomalacia and the subsequent development of cerebral palsy. This is the largest study to date, but further studies continue to be published from centres that have been performing SFLP for some time and overall the outcomes are similar.
Initially this procedure was confined to a few specialised centres in the world. The Eurofetus randomised controlled trial was performed in Europe by experienced practitioners. In the late 1990s the fetoscopic equipment to perform the procedure was being developed and refined by two companies, Karl Storz and Wolf, in conjunction with the centres pioneering the technique. As other centres started to perform the procedure they underwent training and started to audit their own outcomes. It is now performed in many developed countries including Australia (three centres) and soon New Zealand.


(1)Senat, M.V., et al., Endoscopic laser surgery versus serial amnioreduction for severe twin-to-twin transfusion syndrome. New England Journal of Medicine, 2004. 351(2): p. 136-44;
(2)Rossi, A.C. and V. D'Addario, Laser therapy and serial amnioreduction as treatment for twin-twin transfusion syndrome: A metaanalysis andreviewofliterature. American Journal of Obstetrics and Gynecology, 2007;
(3)Graef, C., Ellenrieder,B., Hecher,K., Hackeloer,B.J., Huber,A., Bartmann,P., Long-term neurodevelopmental outcome of 167 children after intrauterine laser treatment for severe twin-twin transfusion syndrome. American Journal of Obstetrics and Gynecology, 2005. 194: p. 303-308;

Conferences

We are looking at the various conferences happening next year at the moment. There are a few in Australasia which are of interest to the health professional interested in MFM:

http://www.fetus2009.com/
http://www.psanz.org.au/

The fetus as a patient in Sydney is mainly about fetal medicine, but also some maternal. PSANZ is a multi-disciplinary conference which attracts MFM health professionals and neonatologists and midwifery health professionals.

I should also plug:

http://www.aocogranzcog2009.co.nz/

This is a general O&G conference in Auckland which will be broad ranging, but has some high-tech and some developing world elements to it. I am part of the organising committee and running a workshop on IT so I think it will be great!

Have a good weekend

Emma Parry

Welcome to MFM New Zealand

Hi and welcome to MFM New Zealand. I hope that this blog will be of interest to women, their families/whanau, clinicians, midwives and anyone else who has anything to do with high risk pregnancy. I am an MFM subspecialist based in Auckland and have a keen interest in providing great care to women in New Zealand where pregnancy may not be going according to plan.
I hope to update this blog regularly with interesting information and links with issues related to MFM (if time allows!)
Any opinions expressed on this blog are my own and do not constitute medical advice.