If identical twins share the placenta in the womb, this can lead to a malnutrition of the children. A life-threatening complication for one or both children. Doctors then attempt to close the vascular connections in the placenta using laser surgery. Gynecologist Nicole Ochsenbein-Kölble has been performing these operations at the USZ since 2008.
How common is this complication and why is it so dangerous for the unborn child?
Around two percent of all pregnancies in Switzerland are twin pregnancies. Of these, around 200 per year are affected by twin transfusion syndrome or feto-fetal transfusion syndrome. About 30 of them undergo surgery, about half of them at the Inselspital in Bern, the other half at the USZ. We are the only clinics in Switzerland that perform this operation.
In twin transfusion syndrome, the blood is not distributed evenly between the two fetuses because one of them pumps more blood to the other. This inadequate care impairs children’s development and puts a strain on their hearts, among other things. If treatment is not given in time, one of the children almost always dies, or even both. If things go well, however, the children catch up again and do not suffer any permanent damage.
But obviously only some of the cases are operated on?
Yes. The difficult part of the syndrome is deciding whether and when to intervene. In some cases, it is clear that action must be taken immediately. Sometimes, however, the supply regulates itself again; in this case it is sufficient to monitor the pregnancy closely for the time being. Twin transfusion syndrome can occur at any time during pregnancy, but we cannot operate at every stage. If the pregnancy is still at an early stage and the operation is not urgent, we can often wait until a time when the children have a good chance of survival, even if they are born prematurely.
How does the operation work?
The mother is only given a local anesthetic and a sleeping pill. This ensures that the children and the mother are a little calmer. An optical device and a laser fiber are inserted into the uterus via a small puncture. I then use the laser to separate blood vessels in the placenta and thus create a separate part for each child. Sometimes it is also necessary to close the umbilical cord of one non-viable twin so that the other can survive. During the operation, we constantly monitor the situation using ultrasound.
A high-risk operation. What complications can there be?
You have to have respect for every operation because, despite the best clarification, you never know exactly what you will encounter. In addition to irregular breathing movements of the mother, which make the operation more difficult, we fear above all premature rupture of the membranes and premature birth with all its dangers. During the procedure, the amniotic sac is punctured, which unfortunately often triggers a rupture of the membranes. The risk of this happening is up to 50 percent.
This means that the parents and you must expect that one or both of the children will die.
The chance of survival is 80-90 percent for one child and 50 percent for both, depending on the situation. We talk openly with the parents about this. These are difficult but important conversations. Ultimately, the parents must make the decision to operate. Nor can we make any promises about the outcome. We experience surprises ourselves, for example when a child that was undersupplied and therefore tiny survives against all odds and is born healthy.
The operation is part of cutting-edge medicine; you have been performing it for several years. What progress would you like to see in the future?
We are conducting intensive research into how we can avoid the most common complication, premature rupture of the membranes. To achieve this, we must be able to close the amniotic sac quickly or stimulate it to heal. We have developed a kind of umbrella that remains behind when the instruments are removed and automatically closes the opening from the inside. We are now testing this. There is also room for improvement in the instruments.
You have a whole gallery of children’s pictures to remind you of successful interventions. Is there a case that is very special to you?
The medically interesting and challenging cases are one thing. When a couple then named their twin girls after my colleague Franziska Krähenmann and myself, it was very touching and made us very happy.
