The identification of proteins associated with a potentially fatal pregnancy complication has raised hopes that physicians can detect the problem before delivery and act to reduce risks.
Placenta accreta spectrum (PAS) occurs when the placenta penetrates the body. Depending on the severity of PAS, the placenta can attach to the uterine muscle or penetrate deeper and latch onto the bladder and other organs. PAS is a factor in some of the 900 maternal deaths that occur during delivery in the U.S. each year because it is associated with abnormal placenta delivery and heavy bleeding.
Around half of PAS cases are found using ultrasound prior to delivery, allowing physicians to take steps that reduce the risk of catastrophic maternal hemorrhage and death. However, there remains a need for tools capable of detecting the other cases.
Writing in the journal Scientific Reports, researchers from Brigham and Women’s Hospital, diagnostics startup NX Prenatal, and other organizations shared details of their work to address the unmet need. The collaborators ran a nested case-control study of 35 cases and 70 controls to find circulating microparticle (CMP) protein panels that identify pregnancies complicated by PAS.
CMPs are extracellular vesicles that enable cell-cell communication. Using size exclusion chromatography and liquid chromatography with tandem mass spectrometry, the scientists isolated and identified CMP proteins at the maternal-fetal interface in plasma samples taken at different points in the pregnancy.
In samples taken after a median of 26 weeks of gestation, the researchers found five CMP proteins that distinguished PAS patients from controls. The mean area under the curve (AUC) for the five proteins was 0.83. AUC is an overall summary of diagnostic accuracy in which 0.5 indicates a test is no better than a coin toss and 1 is perfect. Four proteins, with an AUC of 0.78, were found in samples taken after 35 weeks.
The discovery of the proteins, coupled to other changes such as iron homeostasis, suggests that it may be possible to detect PAS during the second and third trimesters using a blood panel.
Dr. Hope Yu, a maternal-fetal medicine physician at Brigham, explained the significance of such a test in a statement.
“It is so important to identify these cases prior to delivery," Dr. Yu said. "If we can identify a PAS case during pregnancy, the patient can then make a potentially life-saving choice to deliver in a tertiary delivery center with specialized providers. Having an experienced, multidisciplinary team by your side during a PAS birth can make an enormous difference when it comes to mortality and morbidity outcomes.”