Preeclampsia screening in the 11th-14th gestational week
The detection of women belonging to the preeclampsia risk group in the first trimester during the OSCAR test is very important as the timely initiation of low-dose aspirin therapy can contribute to the growth of vascular enlargement of the developing placenta, thereby improving the attachment to the placenta and reducing the chance of the onset of early preeclampsia.
With the OSCAR test in the I. trimester, it is possible to accurately identify 76.7% of women at risk who may develop early preeclampsia before the 37th week, and women who develop preeclampsia after the 37th week with 43.1% accuracy. In the case of a pregnancy with twins, it is possible to identify all women who may develop early preeclampsia before the 37th week. In the case of twins, the disadvantage of the test is that 75% are false positive results.
The studies have shown that at low doses, aspirin intake prior to the 16th week of pregnancy improves the blood supply of the developing placenta, and in 62% of cases reduces the onset of early preeclampsia, leading to a preterm delivery before the 37th week of pregnancy, and in 30% of cases the preterm detachment of the placenta. Therefore, it is recommended that women with elevated risk should take 150 milligrams of aspirin once a day in evenings up to the 36th week of pregnancy.
Aspirin only works if it is taken. When a woman in a high-risk group uses 150 mg of aspirin regularly every day, it is possible in 74% of cases to prevent early preeclampsia that occurs before the 37th week of pregnancy.
The aspirin prophylaxis does not help prevent preeclampsia in women with chronic hypertension. If a woman of a risk group, not suffering from chronic hypertension, uses 150 mg of aspirin regularly every evening, then it is possible in 95% of cases to prevent early preeclampsia that occurs before the 37th week of pregnancy.
- High-risk group. This group consists of women who, as a result of the screening, had a risk of early preeclampsia before the 34th week of pregnancy greater than 1:200. The group consists of 10% of women who participated in the study and 75% of them develop preeclampsia before the 37th week of pregnancy. These women are recommended to start with the aspirin prophylaxis (150 mg intake in the evening) up to the 36th week of pregnancy and reassessment of the preeclampsia risk at week 20 of pregnancy.
- Low-risk group. This group consists of women who, as a result of the screening, had a risk of early preeclampsia before the 34th week of pregnancy less than 1:200. The group consists of 90% of women who participated in the study and these women become reassured that preeclampsia before the 37th week of pregnancy was very unlikely. Reassessment of the risk is suggested during the 20th week of pregnancy, since then the detection of early preeclampsia is more accurate.
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