Postpartum hemorrhage, severe bleeding after childbirth, is a leading cause of maternal mortality around the world. But many of these deaths can be prevented—and a real-time blood-monitoring technology called viscoelastic testing (VET) could play a crucial role. Though used in parts of Europe, VET is not yet a standard part of maternity care in the United States.
A new sweeping review from the Southern California Evidence Review Center, part of the Keck School of Medicine of USC, brings U.S. hospitals a step closer to improving treatment of maternal hemorrhage with VET. The study, just published in the International Journal of Obstetric Anesthesia, includes a summary of findings from 156 research publications. The study was commissioned by the Patient-Centered Outcomes Research Institute (PCORI) and included interviews with patients, clinicians and policymakers.
“Maternal mortality is a serious public health challenge, including in the U.S., which is especially troubling because the majority of cases are preventable. The problem is that severe postpartum hemorrhage is a rare event, so hospitals are not always prepared for it,” said Susanne Hempel, PhD, professor of clinical population and public health sciences at the Keck School of Medicine and director of the Southern California Evidence Review Center, who oversaw the review.
VET is a minimally invasive test that detects how well blood is clotting and gives information about what type of blood transfusion—such as platelets, plasma or whole blood—can stop a patient’s hemorrhage. VET is currently approved by the U.S. Food and Drug Administration to guide blood transfusions during cardiac surgery, orthopedic surgery and trauma, but not for use during childbirth.
“Because it is a point-of-care test that can be done at a patient’s bedside, it provides fast and detailed results within minutes, helping physicians make treatment decisions in real time,” said Carla Janzen, MD, PhD, professor of obstetrics and gynecology at the University of California, Los Angeles David Geffen School of Medicine and the first author of the publication.
The review revealed that VET holds promise, but that high-quality research on its use for maternity care is limited. A major takeaway is the need for a large-scale, U.S.-based research study to test VET’s effectiveness in this context, as well as a broader professional consensus about when and how the technology should be applied. Insights from the report can help guide policy, research priorities and other key decisions around the use of this technology, the researchers said.
Barriers to adoption
To compile the report, the researchers reviewed 156 publications on the use of VET in obstetric care, finding growing evidence of its effectiveness in managing postpartum hemorrhage. But only two of the studies reviewed were randomized controlled trials, the gold standard in research that compares outcomes between a treatment group and a control group. Most other studies were smaller or less rigorous, such as case reports or observational studies.
“The problem is that postpartum hemorrhage is rare, so studying it requires massive sample sizes. Researchers must observe cases for many years or work within a very large system,” Hempel said.
Another solution: Unite multiple centers, using standardized procedures, to collect and analyze data on the use of VET during childbirth. A large, multi-center randomized controlled trial can help prove the technology’s efficacy, establish a consensus on best practices for its use, and generate data on how specific pregnancy conditions, such as preeclampsia, might require a specialized approach.
In addition to reviewing the scientific evidence on VET, Hempel and her colleagues interviewed patients, providers, researchers and policymakers. Their questions explored why the technology has not yet been adopted in the United States and what changes could help expedite its rollout.
They found that a major barrier to adoption was the cost of setting up VET systems, training clinicians to use them, and integrating them into hospital protocols. The lack of scientific consensus on best practices, such as when and how VET should be used, was another reason for the lack of use.
“If we want this technology to be used, we also need protocols on what to do when. What are the criteria for action?” Hempel said.
Benefits beyond survival
Beyond its life-saving potential, using VET may also lead to other benefits. While the systems are expensive to adopt, they have the potential to generate cost savings over time, Hempel said. By identifying which blood components are needed—such as platelets or plasma—VET can help reserve more expensive whole blood products for situations where they are truly necessary.
The technology could also help reduce health disparities by providing faster, more precise treatment for complications that disproportionately harm certain groups. In the United States, Black women and women living in rural areas are more likely to die in childbirth than women from other groups—and timely access to VET could help close that gap.
Even as research continues, Hempel said the arguments for adopting the new technology are becoming increasingly clear.
“Sometimes, the potential of a technology makes it worth using while the evidence continues to roll in,” she said. “People use parachutes not because they are convinced by the evidence from randomized controlled trials, but because they’re convinced by the logic of it.”
The full report and an issue brief for policymakers are available through the PCORI website.
About this research
In addition to Hempel and Janzen, the study’s other authors are Diana Zhang, Sarah Herman, Ivonne Mendez, Aita Robertson, Tyla Gilliams, Kimny Sysawang, Sachi Yagyu, Aneesa Motala and Danica Tolentino from the Southern California Evidence Review Center, Keck School of Medicine of USC, University of Southern California.
This work was supported by the Patient-Centered Outcomes Research Institute (PCORI). All statements, findings, and conclusions in this publication are solely those of the authors and do not necessarily represent the views of PCORI. This publication was developed through a contract (IDIQ-TO#01-USC-ENG-RSNT-05-01-2024) to support PCORI’s work. Questions or comments may be sent to PCORI at info@pcori.org.
END