Operating on the unborn

Will foetal surgery become more common? CC0 image via Pixabay

Will foetal surgery become more common? CC0 image via Pixabay

Remarkable ingenuity is employed every day in the operating theatre. What’s more, certain patients receiving surgery haven’t even been born yet. Surgically saving unborn lives doesn’t exactly sound simple. So how does it work?

If a prenatal scan reveals a severe birth defect in an unborn child, and parents make an informed decision to progress with the pregnancy, there are two options. There is firstly the option of waiting until the baby is born, before it’s whisked off into theatre – for example, for surgery to correct Tetralogy of Fallot, a common congenital heart condition. Secondly, there is the possible option to operate on the developing foetus, either by opening the mother’s womb, or by employing ‘keyhole’ surgical techniques through a tiny cut in her abdomen.

Such options might seem incredibly risky, both for the mother and her developing foetus. But for some birth defects, foetal surgery gives better prospects than waiting for delivery – even if this does involve early exposure for the developing foetus to the outside world. Michael Skinner was the first baby to survive successful foetal surgery. Michael had a life-threatening congenital defect that meant urine couldn’t drain from his body. His bladder was ballooning outwards and crushing the developing lungs and kidneys. The decision to operate was an ethically fraught one, due to the operative risk posed towards Michael’s mother, Rosa Skinner. To complicate things further, Michael had a healthy twin. Surgeon Michael Harrison said this was an ‘ethical dilemma – we were just in agony at the time’. After deliberation with ethicists, Harrison operated on Michael when he was in the womb alongside twin sister Mary. Both babies were born healthy to their mother by Caesarian section two weeks after the operation.

There are two types of foetal surgery. Open surgery involves anaesthetising the mother (the foetus receives the anaesthetic from the mother’s blood supply), before opening the uterus and removing the foetus. Because the foetus is entirely dependent on the mother’s placenta for oxygen and nutrient supply during development, it can spend as long as three hours out in the open, connected to the mother by its umbilical cord. The foetus is then returned to its mother’s womb and the pregnancy is carefully monitored up to delivery by Caesarian section. The second option is keyhole surgery, which involves making a small incision in the mother’s abdomen after anaesthetising the foetus. This option is less invasive and allows a shorter recovery time (and possibly fewer health risks) for the mother.

Remarkable as these procedures may be, they are also rare. Due to the extremely specialist skills required and the potential danger to mother and baby – some procedures have been discontinued. Around 1000 foetal procedures are carried out globally each year. But congenital anomalies aren’t uncommon. For example, approximately 1 in 33 infants are estimated to be born a birth defect in the US. While some of these are relatively minor, worldwide, congenital anomalies accounted for over 250,000 infant deaths in 2013.

There are several congenital anomalies which are operable in utero. While America is the home of foetal surgery, other countries are getting on board. Asia’s first facility for open foetal surgery opened late last year and just this month the first foetal heart surgery was conducted in South Africa. A scan had revealed a lethal heart malformation which had led to a buildup of fluid around the heart, affecting cardiac rate and rhythm. In order to correct this, doctors performed a delicate procedure called pericardiocentesis: a needle was directed into the foetal chest cavity to extract excess fluid and relieve pressure on the heart. Ultrasound was used to guide the needle. The surgery appeared to be a ‘resounding success’ and the foetus is due to be delivered before Christmas 2016.

Australia marked its first in utero operation this July, as Brisbane doctors worked to repair a case of spina bifida (‘split spine’), a type of defect in which the bottom of the spinal cord either does not develop properly, or is exposed to the open. Repair (closing this opening) is usually performed after delivery, but by this point the exposed spinal cord may have already been damaged through exposure to amniotic fluid. This can lead to paralysis in the affected child. The developing brain may also have been exposed to pathogens through the spina bifida opening, possibly causing brain damage. Only the most severe type of spina bifida (Myelomeningocele) qualifies for foetal surgery, as the operation remains experimental and does not ‘cure’ the condition, rather aims to minimise damage. It’s also highly invasive and risky for the mother. In future a tiny robot may aid in developing less invasive spina bifida surgeries, as part of a £10m funding boost awarded to UCL.

Our medical care today – and, sadly, inequality of access worldwide – is staggering. It seems likely that foetal surgery will become more common, and its benefits may not be limited to richer countries. According to South African surgeon Samad Shaik, ‘foetal surgery can contribute more to the developing world than we probably think’ – in particular as, post-operation the foetus ‘recuperates for free in the best intensive care unit – its mother’s womb – rather than occupying a precious bed in a neonatal ICU after birth’.

S.

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