Combining standard ultrasound monitoring with non-invasive assessment of blood oxygenation levels in the placenta can help improve pregnancy health and pick up early signs of adverse event onset.
Abnormalities in the placenta are a common cause of adverse pregnancy outcomes including stillbirth. Ultrasound is commonly used to monitor pregnancies and the health of the fetus, but can only provide relatively limited information that mostly relates to visible shape changes and not factors such as oxygen flow to and from the placenta.
To try and improve pregnancy monitoring and provide more in-depth information about placental health, Lin Wang, a researcher at the University of Pennsylvania, and colleagues developed a frequency-domain diffuse optical spectroscopy device that can measure blood oxygenation in the placenta.
Devices to measure blood oxygenation are not new, but currently available devices mostly measure this through the skin (such as the fingertip) and are not configured to assess oxygen flow in deeper organs in the body.
“We’re sending a light signal that goes through the same deep tissues as the ultrasound. The extremely small amount of light that returns to the surface probe is then used to accurately assess tissue properties, which is only possible with very stable lasers, optics, and detectors,” explained Arjun Yodh, who co-led the research and who leads Wang’s lab, in a press statement. “Lin had to overcome many barriers to improve the signal-to-noise ratio to the point where we trusted our data.”
The result of several years development work, the pilot study, published in Nature Biomedical Engineering, included 15 women with normal placental function and 9 with abnormal placentas. The team tested their non-invasive device concurrently with ultrasound scanning in the patients.
After a short period of oxygen supplementation, the device was able to pick up these changes in the placenta of the participants and also detected when levels decreased again demonstrating it was able to measure placental oxygen levels in real time.
These experiments were also able to differentiate the healthy from the unhealthy placentas. “Not only do we show that oxygen levels go up when you give the mom oxygen, but when we analyze the data, both for clinical outcomes and pathology, patients with maternal vascular malperfusion did not have as much of an increase in oxygen compared to patients with normal placentas,” said co-lead author Nadav Schwartz, also based at the University of Pennsylvania.
“What was exciting is that, not only did we get an instrument to probe deeper than commercial devices, but we also obtained an early signal that hyperoxygenation experiments can differentiate a healthy placenta from a diseased placenta.”
Early responses to placental problems can be critical for improving outcomes and potentially saving lives. While more testing and validation is needed before it can be more widely used, the researchers believe this kind of device could help detect signs of placenta-related adverse pregnancy outcomes early and also signs that oxygen flow to the fetus may not be optimal.