Placenta accreta spectrum disorder (PAS) is a life-threatening condition that occurs when the placenta remains attached to the uterus after childbirth. Today, researchers funded by the NIBIB have developed a blood test for the rapid identification of this disease, allowing rapid intervention by specialists in high-risk pregnancies.
Although it occurs in less than 0.5% of pregnancies, PAS disorder is a serious condition in which the placenta becomes anchored too deeply in the uterine wall during pregnancy. The condition can lead to significant blood loss during labor and delivery requiring blood transfusions and intensive care to prevent serious complications, or more tragically, the death of the mother.
Currently, mothers with a history of pregnancy complications are examined by ultrasound for indications of PAS. However, women without this history may also be at risk for PAS, making the current screening protocol insufficient.
Developed by an international team from UCLA and Cedars Sinai Medical Center in Los Angeles, the University of Utah in Salt Lake City, and research institutes in China, the blood test can be performed during the first trimester of pregnancy, allowing early referral to doctors specializing in high-risk pregnancies.
The new approach uses a technology called the NanoVelcro chip, which has been developed over the past 15 years by Dr. Yazhen Zhu and Hsian-Rong Tseng, professors of molecular and medical pharmacology at UCLA. The chip was originally created to detect tumor cells in the blood of cancer patients. The team adapted the chip so that it could detect placental cells in maternal blood samples.
The chip detects a specific cell type associated with the appearance of PAS known as circulating trophoblasts. The NanoVelcro test is relatively straightforward and was designed to be easily performed as part of the normal workflow of healthcare facilities providing antenatal care. It only requires 2 milliliters of blood, from which cells are isolated and incubated on the test chip overnight. The number of trophoblasts and trophoblast clusters captured by the NanoVelcro chip is then counted using a fluorescence microscope. Thus, the identification of an abnormal number of trophoblasts and trophoblast clusters, indicating an increased risk of PAS, can be determined within 24 hours.
The development of this type of innovative yet simple test for PAS is an outstanding example of the types of technologies that the National Institute of Biomedical Imaging and Bioengineering (NIBIB) is supporting to improve maternal and antenatal care around the world. “
Tiffani Lash, PhD, Director, NIBIB Program in Point of Service Technologies-Diagnostics
In tests with more than 100 women, the blood test had an 83.8% probability of confirming the presence of placenta accreta and a 92% probability of excluding it with a negative result.
“Recent population studies have shown that half to two thirds of cases of PAS disorders go undiagnosed before childbirth, highlighting the critical need to develop new technologies for prenatal detection,” says Dr Margareta Pisarska of Cedars Sinai Medical Center, main co-author of the work. “Our study demonstrates promising non-invasive technology for the detection of PAS that does not rely on expensive imaging instruments or expertise to make it accessible to a range of point-of-care settings, including in low-resource areas. “
The team attributes the success of their work to a multidisciplinary approach that brought together experts in obstetrics, pathology, nanotechnology, engineering and microfluidics. The group is currently exploring ways to refine the test to improve its accuracy and reliability.
National Institute of Biomedical Imaging and Bioengineering
Afshar, Y., et al. (2021) Circulating trophoblast cell clusters for early detection of placenta accreta spectrum disorders. Natural communications. doi.org/10.1038/s41467-021-24627-2.