Operating on Denmark's tiniest patients

​Surgery on tiny foetuses in their mother's womb is very much a question of accuracy. The Centre for Fetal Medicine and Pregnancy performs surgery on foetuses as young as 15 weeks.


Ultrasound image of a 24-week-old foetus with a shunt inserted in the chest. The shunt (the long object in the red ring) leads fluid from the dark triangular cavity in the chest into the amniotic fluid at the top of the image.

"For us, everything is small. We've by far the smallest patients in Denmark, and we only work with as tiny, delicate and thin instruments as possible.

Karin Sundberg, a clinical consultant at the Centre for Fetal Medicine and Pregnancy, is standing with a long thin needle in her hand. The needle is the same length as her forearm and is only 1.2 mm thick. At the end of the needle is what at first glance looks like the top of a ballpoint pen – a so-called shunt; a 2.5 cm-long microscopic drain.

The shunt can be used if a pregnant woman is carrying a foetus with accumulations of fluid in the chest cavity. A rare and extremely serious condition, where there is a risk that the lungs of the foetus will not develop normally during the pregnancy.

Rigshospitalet was the first hospital in the world to use this method to treat fluid in the chest just over two years ago. Since then, the hospital has performed almost 20 successful procedures with shunts.

"If we don't remove the fluid from the chest during pregnancy, there's a risk that the child won't be able to breathe when it's born. And it goes without saying that this can have fatal consequences," explained Karin Sundberg.

First in the world with this treatment 

The shunt can be folded together so that it fits into the long, thin needle. The needle is inserted into the skin without local anaesthesia, but the mother and the foetus are given sedatives and pain-relieving medicine via the mother's blood stream. Through ultrasound scans, physicians can monitor the needle's route into the foetus and make sure that the shunt is placed and unfolded in exactly the right location; i.e. with one end in the cavity in which the fluid has accumulated in the chest and the other end in the amniotic cavity containing the amniotic fluid.

"Once the shunt has been placed correctly, and the needle has been pulled out again, the ultrasound scan shows almost immediately how the fluid is being drained from the chest. In our world, we operate in extremely tight spaces, where it is difficult to see what you're doing. Operating on tiny 20 cm-long foetuses, as young as 20 weeks and curled up in the uterus, requires accuracy and a very steady hand. Therefore, it's extremely satisfying every time an operation goes well," explained Karin Sundberg.

When the child is born, the drain is removed. In uncomplicated cases, the child will live with no further problems. However, the child needs to be monitored after the procedure to keep an eye on their development, as the accumulation of fluid can be caused by other diseases. 

Collaboration with other countries is important 

Rigshospitalet is the only hospital in Denmark to offer highly specialised invasive treatment of foetuses during pregnancy – also known as foetal therapy. The hospital performs about 80 procedures a year. Some procedures can be carried out on foetuses as young as 16 weeks and measuring only 16 cm.

"We don't carry out procedures lightly. We're dealing with rare and serious conditions which may result in the death of the foetus, so we have to make an individual assessment every time. We have long and thorough conversations with the women and their partners to weigh the advantages and disadvantages of a possible procedure. Procedures may entail an increased risk of complications and premature birth. Some choose to terminate the pregnancy, whereas others choose the procedure. This is certainly not for everyone," said Karin Sundberg.

Karin Sundberg and her colleagues work closely with colleagues from the other Nordic countries to exchange experiences and results regarding the rarer disorders that may occur in a foetus during pregnancy. Each year, Rigshospitalet also receives couples from Norway and Finland, who come to Denmark to receive treatment for their unborn children.

"Receiving patients from outside Denmark is important to us. We've only just enough patients in Denmark to maintain the competences as well as the high technological and educational level required to perform surgery on foetuses in the uterus. The experience and knowledge that we exchange with other countries will therefore benefit Danish foetuses and future parents in the long term," said Karin Sundberg.

FACTS: Examples of some of the foetal therapeutic procedures offered by Rigshospitalet:

  • Laser treatment in connection with twin-to-twin transfusion syndrome (TTTS) – can be carried out when twins are 16-26 weeks.
    Treatment if there is an imbalance in the blood flow between identical twin foetuses who share one placenta. If the condition is not treated, one or both twins could die, and there is a significant risk of brain injury.

    The treatment is a procedure in which a millimetre-thin endoscopic instrument is inserted through the uterus to cut the shared blood vessels in the placenta using a laser.

  • Blood transfusion – from 15-34 weeks.
    A procedure performed if a foetus shows signs of severe anaemia, for example if the mother's blood group antibodies attack the child's red blood cells.

    In a foetal blood transfusion, an ultra-thin needle is inserted into the blood vessels of the foetus – the needle is monitored by ultrasound. The foetus receives blood through the needle, just like in a normal blood transfusion.

  • Shunts/drains –  from 16 weeks and throughout pregnancy.
    A shunt is inserted into the foetus if the foetus accumulates unwanted fluid in various cavities. Fluid can prevent development and maturity of organs. Therefore, the fluid is led away from the cavity by inserting a shunt between the accumulation of fluid and the amniotic fluid.


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