A new wearable ultrasound patch could allow for continuous fetal monitoring during pregnancy, with results that, according to the first clinical trial, appear consistent with those obtained using traditional ultrasound scans. These are the findings of a study conducted at the University of California San Diego (UC San Diego), where a group of researchers have developed an ultrasound patch called UPatch. The research was published in the journal Nature Biotechnology.
During pregnancy, fetal development is evaluated using ultrasonography, a diagnostic technique that uses high-frequency ultrasound to produce images in real time. The sonogram thus obtained makes it possible to evaluate, in addition to fetal vitality, the unborn child’s biometric measurements, including cranial circumference, abdominal circumference and femur length, the correct anatomical development of organs, and blood flow.
A normal pregnancy involves one ultrasound scan per trimester. It must be conducted by a specialist and, by its very nature, cannot give a continuous picture of how the pregnancy is evolving, but only of the moment when it is performed. Given that these ultrasounds are carried out weeks apart, complications that arise between one scan and the next may not be detected in a timely fashion.
The ultrasound patch, which is soft and engineered to stay firmly attached to the woman's belly even when she is moving, is designed for continuous fetal monitoring, acquiring images of anatomical structures, collecting cardiac activity data, and measuring blood flow rate.
One of the greatest difficulties when developing this device was the constant movement of the foetus and of the umbilical cord, which can cause measurements to be inconsistent. To address this issue, the researchers developed automatic tracking algorithms that can recognise the umbilical cord and follow its movement in real time. This makes it possible to maintain blood flow monitoring even while the mother and foetus are moving, without any manual guidance and without changing the patch's position.
The wearable patch's ability to produce measurements was tested on a sample group of 62 pregnant women. The results showed that UPatch is able to acquire anatomical images and measure blood flow rate, with results that closely match those obtained using standard clinical ultrasound devices.
The device's clinical efficacy was then evaluated in a multicentre clinical study conducted at Jacobs Medical Center at UC San Diego Health and the John Radcliffe Hospital at the University of Oxford, on 52 normal and complicated pregnancies. Women participating in the clinical trial presented with different clinical conditions, including gestational diabetes, gestational hypertension, abnormal fetal growth, and preeclampsia. The latter complication generally develops after the twentieth week of pregnancy and involves a sudden rise in blood pressure and the presence of protein in the urine.
According to the authors, the UPatch represents a useful extended-period ultrasound monitoring system for continuous non-invasive surveillance of fetal health and wellbeing. Thanks to further technological developments intended to make the device capable of operating entirely wirelessly, this tool will be even more practical and easy to use in the future. Looking at the bigger picture, UPatch could expand possibilities in terms of health checks, allowing for continuous monitoring of fetal conditions in high-risk pregnancies.
Photos by Geonho (Tom) Park