New device (top) with the cushion inflated, shown with the computational model (bottom). The built-in cushion gently expands to hold the probe in stable contact with the fetus without causing harm. (John A. Rogers / Northwestern University via SWNS)
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By Stephen Beech
A tiny new probe can monitor an unborn baby’s health inside the womb during surgery.
It is the first device capable of continuously tracking the vital signs of a fetus while still in the uterus, say scientists.
Just three times the width of a human hair, the probe is slim enough to pass through a standard tube already used during surgery and requires no additional incisions.
The American research team that developed the monitor say it could “dramatically improve” safety during procedures in which surgeons operate on a fetus before birth.
Currently, doctors primarily rely on intermittent measurements of fetal heart rate using ultrasound imaging from outside the mother’s body.
However, the new device can be gently inserted through the same narrow port already used in fetal surgeries.
It is the smallest platform developed to date capable of accurately measuring vital signs, according to a study published in the journal Nature Biomedical Engineering.
Bioelectronics pioneer Professor John Rogers, of Northwestern University in Illinois, led the development of the device with Dr. Aimen Shaaban, a fetal surgeon at Ann & Robert H. Lurie Children’s Hospital in Chicago.
Rogers said: “Performing fetal surgery with this sensor really shines a light on an area that’s been in the dark for so long.
“When we operate on a baby after birth, we monitor a variety of parameters, including blood pressure, oxygen and carbon dioxide levels, heart rate and breathing.
New probe is just three times the width of the diameter of a single hair. (John A. Rogers / Northwestern University via SWNS)
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“But for a fetus, who is more sensitive than a baby, we’re very limited.
“We don’t know what their vital signs are.
“Sometimes, the foetal heart rate drops during this procedure signalling low oxygen levels or a low blood pH.
“A slow fetal heart rate can develop abruptly and can even present with a full cardiac arrest for the fetus.
“Our ability to monitor the fetus hasn’t changed in 40 years. The tools just haven’t been there.
“We hope this probe provides multiparameter continuous monitoring of the fetus, enabling corrective adjustments at a very early stage to ensure foetal well-being throughout the procedure and avoiding any instability.”
He explained that once inside the uterus, the device maintains stable, gentle contact with the fetus to reliably track heart rate, heart rate variability, blood oxygen levels and temperature.
In studies on a large animal model, the probe provided accurate, precise, clinical-grade measurements even as the uterus and fetus moved during surgery.
By tracking multiple vital signs simultaneously, surgeons gain a more complete and earlier picture of fetal distress, enabling faster interventions in case complications arise.
This illustration shows how the new probe enters a surgical port to reach a fetus in utero. (John A. Rogers / Northwestern University via SWNS)
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Rogers said: “Right now, clinicians only have a partial picture of how a fetus is doing throughout surgery.
“We were presented with the challenge of designing a technology to monitor vital signs throughout the surgical process without creating an invasive access point or disturbing delicate tissues.
“Our flexible hair-like probe enters a port already used in minimally invasive fetal procedures and provides continuous, comprehensive monitoring without adding risk.”
In rare, complex cases, surgeons perform fetal surgery to correct life-altering or sometimes life-threatening congenital conditions before birth.
One such condition is spina bifida, which affects thousands of babies each year.
Doctors might also perform fetal surgery to treat severe diaphragmatic hernias, urinary tract obstructions, fetal tumors or twin-to-twin transfusion syndrome, a serious complication in which blood flows unequally from one twin to the other.
Those procedures are performed as early as 15 weeks into a pregnancy.
Dr. Shaaban said: “Spina bifida is an opening in the spine that leaves the spinal cord and nerves exposed.
“This birth defect results in a lot of neurologic complications, including leg paralysis and hydrocephalus. Fetal surgery can reduce or even prevent these complications and can improve quality of life.”
(Photo by Jonathan Borba via Pexels)
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Over the past decade, surgeons have increasingly shifted from open fetal surgery – requiring a large incision into the uterus – to minimally invasive fetoscopic procedures, which use tiny instruments inserted through narrow surgical ports.
While the less invasive approach reduces risks for the mother, they also make it more difficult to monitor the fetus.
To address the challenge, the Northwestern team designed a slender, filament-like probe made from soft, flexible materials that can operate safely and gently inside the uterus.
With a width just three times that of a single hair, the probe is slim enough to pass through a standard tube already used during fetoscopic surgery, requiring no additional incisions.
Once inside the uterus, soft robotic actuators enable the surgeon to guide and position the probe with precision.
To ensure the probe stays in place, Rogers’ team designed a tiny, inflatable balloon-like cushion.
The built-in cushion gently expands to hold the probe in stable contact with the fetus.
Rogers said: “The device needs to gently press onto the tissue to form the kind of coupling needed to measure vital signs.
“Miniaturized balloons integrated onto the probe enable this coupling in a soft, minimally invasive manner.
(Photo by Zakir Rushanly via Pexels)
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“Our designs also use a similar mechanism to allow the filament to bend or twist, so that surgeons can robotically position it to a desired location.”
The team integrated multiple miniature sensors into the probe to simultaneously measure fetal heart rate, blood oxygen saturation and temperature.
The device wirelessly transmits data to a monitor outside the body, providing surgeons with real-time feedback throughout the procedure.
The team say it could help surgeons intervene earlier or pause a procedure if a fetus shows signs of distress.
And it also could help give parents more reassurance and peace of mind during anxiety-inducing surgeries.
Dr. Shaaban added: “When a pregnant mum needs a fetal operation, she places a lot of trust in her doctors to make sure that it is safe.
“If we could give her more confidence that her baby will do well, that’s better for everybody.
“Anything we can do to make operations safer for mum and safer for the baby is a huge win.”
