Clinicians from across the country, including Tennessee, Ohio, California, and Texas, joined Ob Hospitalist Group (OBHG) on Oct. 22 for a physician-led conversation on a tool for evaluating hypertension in pregnancy. Dr. Jennifer Risinger, an OBHG market medical director, moderated. She was joined by Dr. Malavika Prabhu, a maternal-fetal medicine specialist at Mass General Brigham, and Dr. Elizabeth Rutherford, an OBHG market medical director.
Why the negative predictive value is a big deal
The sFlt-1/PlGF ratio compares an anti-angiogenic protein with an angiogenic one, a balance that is disrupted early in preeclampsia. In the PRAECIS (Preeclampsia Risk Assessment: Evaluation of Cut-Offs to Improve Stratification) trial, about 1,000 women with singleton pregnancies and hypertension, all meeting criteria for inpatient evaluation between 23 and 35 weeks, had their ratio measured. At a cutoff of 40, the positive predictive value (the chance a high result is right) for preeclampsia with severe features within two weeks was about 65%. The negative predictive value (the chance a low result is right) was 96%. Dr. Prabhu said the ratio predicted that outcome better than AST, ALT, and other standard labs.
FDA cleared the Brahms Kryptor platform in 2023 (cutoff of 40) and the Roche assay in 2025 (cutoff of 38).
‘It is not an indication for delivery’
Dr. Prabhu was clear about the limits. “Even if the test comes back positive, it is not an indication for delivery,” she said. The test cannot tell you whether a patient has severe preeclampsia today.
Its strongest use, she said, is the patient with chronic hypertension who arrives at 29 weeks with a pressure of 165/90 and feels fine. In PRAECIS, the negative predictive value in chronic hypertension was 94%. A low ratio supports uptitrating antihypertensives and planning outpatient care.
She also described a patient at 30 weeks with preeclampsia without severe features whose elevated ratio led to a transfer. Four days later, the patient had a placental abruption and needed an urgent cesarean.
‘Good, better, best’ for your hospital
Dr. Risinger said few attendees in the chat reported in-house testing. Sendout results take two to three days. Dr. Rutherford said manufacturers report in-house turnaround of 30 minutes to an hour, and she outlined a path to get there: meet with your lab director, then build a case from PRAECIS, your patient volume, and your NICU admissions. The two platforms’ ratios are not interchangeable.
She also cited an Oct. 6 study in the Obstetrics & Gynecology journal (a.k.a. the Green Journal). That study of 33 million U.S. births found hypertensive disorders rose 74% from 2016 to 2024. If in-house testing is out of reach, she said, work with your lab on a clear sendout pathway, including an order code in your electronic health record.
Dr. Prabhu added that a protocol for who gets offered testing is key to equity, because it keeps patients from falling through the cracks.
What it doesn’t do yet
Dr. Rutherford said ACOG’s June 2024 clinical practice update positions the test as an adjunct to, not a replacement for, standard surveillance. The panel said it is not for routine prenatal visits. Dr. Prabhu did not believe postpartum use has been studied. Dr. Rutherford could not find concrete Medicaid coverage data.
Watch the full webinar
If you have ever kept a 29-week patient for observation and wondered whether it was necessary, this conversation is for you. The full recording also covers repeat testing every two weeks, aspirin dosing, and how to pitch testing to hospital leadership.
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