A new blood test can be performed in a pregnant person’s first trimester to help assess their risk of developing preeclampsia, a potentially life-threatening pregnancy complication.
It’s the first and only test of its kind available in the United States that can be used between 11 and 14 weeks gestation to determine the risk of preeclampsia before 34 weeks of pregnancy, its maker, Labcorp, announced Wednesday. The first trimester is the period from 0 to 13 weeks of a pregnancy.
However, the new test doesn’t change clinical guidance on preeclampsia, according to the American College of Obstetricians and Gynecologists, also known as ACOG. Some doctors question how it will help.
“It is currently unclear how useful the LabCorp test will be in accurately predicting risk for developing preeclampsia and whether it is appropriate for all pregnant patients,” Dr. Christopher Zahn, ACOG’s interim CEO and chief of clinical practice and health equity and quality, said in a statement.
“Before a screening test can be successfully employed, there needs to be an evidence-based intervention to either prevent or reduce the impact of the disease. We currently have no data on how to reduce the risk for a pregnant patient predicted to have preeclampsia from a blood test early in pregnancy as opposed to clinical factors,” he added.
Preeclampsia is a complication of pregnancy marked by elevated blood pressure and high levels of protein in the urine or other signs of organ damage. The condition typically develops after 20 weeks of pregnancy – in the second trimester – and if left untreated, it can turn serious or deadly for both mother and baby.
There is no cure for preeclampsia, outside of the mother delivering the baby, but some severe cases can be treated with medications like antihypertensive drugs.
Some factors that can put a pregnant person at risk of preeclampsia include being older than 35; being pregnant for the first time; having obesity; having a family history of preeclampsia; having diabetes, high blood pressure, kidney disease or an autoimmune disease; having twins or triplets; or having undergone in vitro fertilization.
The new screening test evaluates any patient’s risk of preeclampsia by 34 weeks gestation, which is the third trimester, and provides a comprehensive risk assessment with up to 90% sensitivity and 90% specificity, according to Labcorp. Sensitivity refers to the test’s ability to accurately identify pregnancies at high risk, and specificity refers to its ability to accurately identify pregnancies that are not at high risk.
Doctors who think their patients might benefit from this screening can talk to their patients about the option, order the test and get results within a few days.
“This is one more tool in the tool belt for clinicians in the US and beyond to help deliver better maternal outcomes,” said Dr. Brian Caveney, Labcorp’s chief medical and scientific officer. About 1 in 25 pregnancies in the United States is affected by preeclampsia, and it is one of the leading causes of maternal death.
Options are limited for preeclampsia risk screening. Before the launch of the new test, at-risk patients could screen for their preeclampsia risk only during the second or third trimester of pregnancy if they were both symptomatic and hospitalized, and even that test was just launched last year.
The new first-trimester test isn’t a diagnostic test but a risk assessment tool to determine whether someone is more likely than average to develop preeclampsia during their current pregnancy, “along with all the other questions your doctor might ask you during a first-trimester visit,” Caveney said.
The screening results can lead to “a whole bunch of slight changes in the prenatal care that you get from your doctor, based on the results of this risk predictor tool early on,” he said.
Those changes may involve having more doctor visits to monitor your pregnancy, checking your blood pressure at home at least once a week, being mindful to not overexert yourself during exercise or at work or, if recommended by your physician, taking a low-dose aspirin preventively.
The US Preventive Services Task Force recommends the use of a low-dose aspirin as preventive medication after 12 weeks gestation in people at high risk for preeclampsia, but some people and their providers may not know that they’re at high risk, especially if it is their first pregnancy.
“At least half or more of cases of preeclampsia are potentially preventable,” Caveney said. “If you identify it earlier in the pregnancy, you’re more likely to be able to do things that lead to a healthier pregnancy and, therefore, hopefully a healthier delivery.”
The new screening test is a laboratory-developed test or LDT, so it does not require approval by the US Food and Drug Administration to be performed.
Labcorp is in talks with health insurance plans to ensure that the test could be covered, Caveney said, adding that the screening assay has a list price of about $240.
How the risk assessment works
The risk of preeclampsia also has racial disparities. In the United States, the rate in Black women is about 60% higher than in White women. In general, Black women are three times more likely to die from a pregnancy-related cause than White women, according to the US Centers for Disease Control and Prevention.
“Preeclampsia is one of the main reasons why there is such a significant disparity in maternal outcomes,” Caveney said. “With a focus on health equity, we think that better, more evidence-based preeclampsia screening can hopefully help address that, along with lots of other social services and health services and prenatal care to hopefully improve outcomes for pregnancies in the US and beyond.”
The new screening test works by identifying and measuring four biomarkers that are associated with preeclampsia risk.
According to Labcorp, those biomarkers are the placental growth factor or PIGF hormone in the blood; pregnancy-associated plasma protein-A or PAPP-A in the blood; a blood pressure measurement of the average arterial pressure in the arteries; and the patient’s uterine artery pulsatility index or UtAPI, which is measured during an ultrasound.
Having low levels of PlGF and PAPP-A may suggest that the placenta is developing and functioning poorly, according to Labcorp, while high levels of arterial pressure and UtAPI may indicate elevated blood pressure and decreased blood flow in the uterine artery.
One study published in 2018 in the journal Ultrasound in Obstetrics and Gynecology found that the performance of screening “is substantially improved” when the screening method includes maternal factors along with biomarkers, such as measurements of mean arterial pressure, UtAPI, PIGF and PAPP-A.
Some doctors raise questions
Not all physicians say they would recommend the new screening test for their patients.
“The utility of the test in managing patients has yet to be proven and it is not clear that it helps more than it could possibly hurt. It is not clear that the use of this test is any better than the current standards for prenatal care,” Dr. Christian Pettker, chief of obstetrics at Yale-New Haven Hospital and a professor at Yale School of Medicine, wrote in an email.
“It is not clear to me that this is appropriate for all patients who are pregnant in the first trimester. Perhaps the most applicable group could be for patients who had preeclampsia in a prior pregnancy, though these patients already have a high risk and are often followed differently in their pregnancy,” Pettker wrote.
“While the test is modestly good at predicting which patients may develop preeclampsia, it isn’t clear how many patients are improperly told that they will develop preeclampsia,” he added. “I would not underestimate the number of patients affected by a false positive.”
ACOG’s Zahn agreed that false assessments come with risks.
“With any new screening tool, it’s always important to ensure that the benefits outweigh the risks,” Zahn said.
Pettker also had some questions about how the test would be administered to evaluate a patient’s preeclampsia risk, based on biomarkers, and how the ultrasound measurement of uterine artery blood flow “is not a standard test done by ultrasound units or physicians and requires very specific expertise and training.”
Labcorp plans to talk with physicians and maternal-fetal specialists about the components of the test, Caveney said, but he added that the screening test could still be ordered using the blood-based biomarkers and regular blood pressure readings.
“More data is better but not necessary, meaning this test performs best statistically if we have all of the pieces of data from the doctor in order to perform it. However, not every ob-gyn office or ultrasound center routinely has the ability to calculate this uterine artery pulsatility index,” he said.
“If they don’t provide it, we will still perform the test and give an indication of risk. It just reduces the sensitivity or the likelihood of us being able to accurately predict the risk of preeclampsia,” he said. “It takes it from a sensitivity of around 90% to the high 70s, which is still significantly higher than assessing traditional maternal risk factors alone.”
Losing a baby ‘should not be the screening’
Eleni Tsigas, chief executive officer of the Preeclampsia Foundation, said that a screening tool like the new first-trimester test could have “significantly” changed her pregnancy experience if it had existed at the time of her first pregnancy in 1998.
“My daughter died, and it was all due to a last-minute emergency,” she said.
Tsigas was diagnosed with preeclampsia only 11 weeks before her due date, and due to the complications of preeclampsia, her daughter, Nikonia Evangelia Tsigas, was stillborn.
At the time, Tsigas said, she had only one risk factor: Her daughter was her first pregnancy.
“But losing your first baby should not be the screening test that you’re at high risk,” Tsigas said. “So many people are completely caught off-guard in their first pregnancy when they develop preeclampsia, because they didn’t have any of these risk factors other than it was their first pregnancy.”
Tsigas and her husband went on to have two more children after that first pregnancy, their sons Jordan and Jonathan. For those pregnancies, Tsigas said, she and her care team were more aware of her preeclampsia risk, they monitored her health closely, and she took a low-dose aspirin when recommended by her doctor.
But something like the newly launched first-trimester screening test, “if it’s done right, it has the potential to eliminate those surprise cases” of preeclampsia, Tsigas said.
“The reason I emphasize ‘done right’ is because what we don’t want to do is add another tool to the toolbox that’s only accessible by some people. That’s only going to increase disparities,” she said.
“This has issues with payer coverage and education and making sure that all women, no matter their socioeconomic status, are aware that this kind of information should be available to everybody. If it is, it has the potential to reduce the disparities we’re seeing in maternal health outcomes and neonatal health outcomes,” she said. “Tests like this absolutely move the bar.”
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