First-trimester screening tests for preeclampsia have low positive predictive value, and there are no data demonstrating that they lead to improved outcomes, according to a committee opinion published by the American College of Obstetricians and Gynecologists. The opinion appears in the September issue of Obstetrics & Gynecology.
"Taking a detailed medical history to evaluate for risk factors is currently the best and only recommended screening approach for preeclampsia; it should remain the method of screening for preeclampsia until studies show that aspirin or other interventions reduce the incidence of preeclampsia for women at high risk based on first-trimester predictive tests," the committee writes.
Biophysical tests include uterine artery Doppler velocimetry and serum markers such as placental growth factor pregnancy-associated protein A. Studies have used these in combination with other risk factors to find associations with hypertensive disorders of pregnancy, including preeclampsia.
In theory, the committee writes, such tests would allow clinicians to provide more intensive surveillance or preventative therapies, but in practice, there is no evidence to suggest the currently available tests and therapies lead to better outcomes.
"Given the relatively low prevalence of early-onset preeclampsia, screening tests will need to have sensitivities and specificities well above what is currently achievable to produce meaningful [positive predictive values]," they write.
One study showed that only 7% of women identified with screening went on to develop early-onset preeclampsia, requiring a large number of women to be identified as high risk to detect a single case, the committee reports.
Low-dose aspirin has been shown to reduce severe preeclampsia and other complications in women who started taking it before 16 weeks, but these studies used clinical risk factors to identify the women who could benefit from taking it.
The authors say that studies using biophysical screening are needed to determine whether treatment based on screening test results is beneficial. They write, "For a first-trimester risk assessment for preeclampsia to be useful in clinical practice, future screening tests will need to have sensitivities and [positive predictive values] high enough to accurately identify women who will develop preeclampsia, and interventions will need to be available that improve clinical outcome in women who test positive."
The authors have disclosed no relevant financial relationships.
Obstet Gynecol. 2015;126:689. Abstract
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Cite this: ACOG Warns Against First-Trimester Preeclampsia Screening - Medscape - Aug 24, 2015.