Researchers at Northwestern University and Ann & Robert H. Lurie Children’s Hospital of Chicago have developed a new device that can continuously monitor a fetus’s vital signs during surgery in the uterus. This is the first time such continuous monitoring has been possible.
The soft, flexible probe is designed to improve safety during fetal surgeries by providing real-time data on heart rate, heart rate variability, blood oxygen levels, and temperature. Currently, doctors use ultrasound imaging from outside the body to check fetal heart rate at intervals. The new device can be inserted through the same port used for fetal surgeries and keeps gentle contact with the fetus throughout the procedure.
In animal studies, the probe delivered accurate clinical-grade measurements even as both uterus and fetus moved during surgery. By tracking several vital signs at once, surgeons can detect distress earlier and respond more quickly if complications arise.
The study was published in Nature Biomedical Engineering and represents the smallest platform so far that can accurately measure these vital signs.
John A. Rogers of Northwestern led device development with Dr. Aimen Shaaban, a fetal surgeon at Ann & Robert H. Lurie Children’s Hospital of Chicago. Rogers said, “Initially, Dr. Shaaban reached out to our lab to ask if we could adapt our vital signs monitoring systems for premature babies and apply them to fetuses during surgery,” adding, “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.”
Dr. Shaaban explained some of the challenges: “Performing fetal surgery with this sensor really shines a light on an area that’s been in the dark for so long,” he said. “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. 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 fetal heart rate drops during this procedure signaling 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 fetal well-being throughout the procedure and avoiding any instability.”
Surgeons sometimes perform operations before birth to treat conditions such as spina bifida or severe diaphragmatic hernias as early as 15 weeks into pregnancy—procedures that are increasingly done using minimally invasive techniques rather than open surgery.
Dr. Shaaban described spina bifida: “Spina bifida is an opening in the spine that leaves the spinal cord and nerves exposed,” he said.“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.”
The team designed their slender probe using soft materials so it could safely pass through standard tubes used in fetoscopic surgeries without needing extra incisions.The probe uses robotic actuators for precise positioning inside the uterus.A small inflatable cushion holds it gently against fetal tissue while sensors measure multiple health indicators.Data transmits wirelessly outside for real-time feedback.
Rogers explained,“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.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.”
Continuous monitoring may help surgeons intervene sooner if distress appears.It also aims to reassure parents about safety.Dr.Shaaban noted,“When a pregnant mom 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 mom and safer for baby is huge win.”
The research was supported by Querrey-Simpson Institute for Bioelectronics and Ann & Robert H.Lurie Children’s Hospital Foundation.Co-first authors include Jianlin Zhou,Mingzheng Wu,and Haohui Zhang from Rogers’ lab;Dr.Steven Papastefan from Shaaban’s lab;and Xiuyuan Li,a former graduate student in Huang’s lab.
Ann & Robert H.Lurie Children’s Hospital of Chicago remains Illinois’ only independent,research-driven children’s hospital,and serves as pediatric training ground for Northwestern University Feinberg School of Medicine.It conducts research through Stanley Manne Children’s Research Institute focused on improving child health nationwide.
