While conventional screening tests can detect only 30% of the women who will develop preeclampsia, new predictive tests can help, reducing the occurrence of this disease in up to 89% of the women.
Preeclampsia stands out among the hypertensive disorders with the greatest impact on maternal and neonatal health affecting about 5-7% of pregnancies and is being consider one of the leading causes of maternal and perinatal mortality and morbidity worldwide. According to the Preeclampsia foundation, an estimated 10 million women develop preeclampsia each year, and 76,000 pregnant women die from preeclampsia and related hypertensive disorders.
The pathogenesis of preeclampsia is not completely clear, but it is known to be related to placental disorders that may occur in early pregnancy, followed by generalized inflammation and progressive endothelial dysfunction. According to the International Society for the Study of Hypertension in Pregnancy, this disorder is characterized by the presence of systolic blood pressure higher than or equal to 140/90 mmHg in: 1) At least two measurements within at least 4 hours between them; 2) after 20 weeks of pregnancy in previously normotensive (normal blood pressure profile) women; and 3) proteinuria that occurs after 20 weeks of pregnancy and may occur up to 6 weeks after childbirth.
Preeclampsia follow-up and control is performed by monitoring acute hypertension, preventing seizures, and applying clinical management that help in the achievement of a full-term pregnancy. In patients diagnosed with preeclampsia and close to the full-term pregancy (with equal to or more than 37 weeks of pregnancy), when the fetus is mature, the childbirth is an effective way to treat and optimize pregnancy outcomes. In preterm pregnancies, the risk of proceeding with the pregnancy should be evaluated against the possibility of developing multisystemic disorders, that is, the worsening caused by preeclampsia leading to maternal organ dysfunction, which may result in clinical complications such as eclampsia and HELLP syndrome (hemolysis, elevated liver enzyme levels, and low platelet count.
The risk of developing preeclampsia is currently identified based on the clinical history, considering the main risk factors for the development of the disease, such as: nulliparity, increased body mass index, gestational diabetes, prior history of preeclampsia or chronic hypertension. However, only 30% of women who will develop preeclampsia can be detected by this screening. Studies suggest that maternal serum markers such as free beta-hCG, pregnancy-associated plasma Protein-A (PAPP-A), placental protein 13 (PP13), Inhibin-A, placental growth factor (PIGF), A disintegrin and metalloproteinase 12 (ADAM12) could improve disease prediction in the first trimester of pregnancy.
Nowadays, early identification of women at risk for preeclampsia could lead to a more effective prenatal care, disease management and treatment. The prospective multicenter ASPRE trial conducted the first-trimester screening for preeclampsia in 26,941 singleton pregnancies, combining maternal factors such as average blood pressure, uterine artery pulsatility index (UtA-PI), PAPP-a and PIGF serum levels between 11-13th week of pregnancy, detecting 76.6% of early preeclampsia and 38.3% preeclampsia. According to Dr. Eduardo Becker, Brazilian obstetrician and gynecologist, specialist in Ultrasound and Fetal Medicine, following the ASPRE study, the largest randomized clinical trial to date, the use of low doses of AAS (acetylsalicylic acid) in patients at higher risk for preeclampsia (PE) can reduce the occurrence of this disease by up to 89% (PE<32 weeks), 82% (PE<34 weeks), and 62% (PE<37 weeks). Dr. Eduardo Becker also declared: “It should be noted that preeclampsia is one of the diseases that most kill pregnant women and is responsible for millions of premature births with serious consequences for the rest of the life of the conceptus.” And completed: “There seems to be no doubt that AAS should be administered whenever necessary. The question is: who should make use of it? How to define the risk group?”
The American College of Obstetricians and Gynecologists (ACOG) proposes to classify preeclampsia as mild and severe, based on the level of hypertension, proteinuria, and involvement of preeclampsia. For screening of the high-risk patients, the ACOG suggested to use only anamnesis data and body mass index (BMI) to track the disease, obtaining reasonable detection rate and false positive rates of almost 70%. With similar anamnesis and BMI criteria, but stricter cut-offs, England’s National Health Service reduced the false positive rate to 10%, unfortunately also reducing the detection rate to unacceptable nearly 40%.
In this search for early and accurate screening guidelines, the London Fetal Medicine Foundation recently suggested an algorithm that associates anamnesis and BMI data with the average uterine artery pulsatility index, pregnant woman’s average blood pressure and biochemical markers, especially PlGF. According to Dr. Eduardo Becker, who has been working with fetal medicine for over 20 years, “With this algorithm, the detection rate increases to 90% in preeclampsia before 34 weeks, and to 75% in preeclampsia before 37 weeks, with false positive rate of 10%. Although this test has yet to be validated in other countries, including Brazil, the increase in the average blood pressure, average artery pulsatility index, and PlGF biochemical marker appears to demonstrate that this is the most appropriate and promising test.”
Using the algorithm that employs anamnesis and biochemical data, SYNLAB has developed two exams aimed at early identification and diagnosis of preeclampsia. The Preeclampsia – Screening test is an exam that allows you to know the risk of developing preeclampsia in the 11-13th weeks of pregnancy. The test combines the analysis of PlGF (placental growth factor) levels along with the PAPP-A (pregnancy-associated plasma Protein-A (PAPP-A) parameters, blood pressure, and ultrasound. The Preeclampsia – Diagnosis test, on the other hand, is a test that allows to distinguish healthy women from women with preeclampsia, and which combines the analysis of the sFlt-1/PlGF ratio (soluble fms-like tyrosine kinase-1 / placental growth factor) with blood pressure and proteinuria determination. This test is indicated from the second mid-pregnancy.
The tests can determine the risk of developing preeclampsia or its early diagnosis, which enables the administration and application of interventions necessary to control the risks of maternal and fetal complications. As Dr. Eduardo Becker points out – “The disease is serious, the consequences are important, and the prevention is simple. Tracking is therefore indispensable!”
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