Prenatal screening

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It’s possible to determine, as soon as the 11th week of pregnancy, the health of the fetus and the risks of abnormalities that could affect its health and that of the mother.

At Fertilys, we offer prenatal screening using fetal ultrasound combined with the measurement of proteins in the maternal blood. It applies to all pregnant women, regardless of their age, and is not a danger to the fetus.

In some cases, a fetal DNA test is also offered. Since fetal DNA circulates freely in the mother’s blood, this test is performed using a blood test.

Screening and diagnosis... what’s the difference?

Prenatal screening is a non-intrusive medical exam that only requires an ultrasound and a blood test on the mother. The data collected is then used to establish a statistical risk, or the probability that the fetus will or will not have a serious abnormality. Prenatal screening is an evaluation of risks and not an absolute certainty.

However, to obtain a definitive answer to the question of exactly how many chromosomes are present in the fetal cells, a prenatal diagnosis is required. Two intrusive techniques are used to obtain an unequivocal result:

  • Amniocentesis consists in withdrawing amniotic fluid containing fetal cells using a needle.
  • Trophoblast biopsy involves removing some cells from the placenta.

These diagnostic techniques are not without risk: in 1% of cases, they can result in a miscarriage. Consequently, trustworthy screening tests are important to limit the use of these diagnostic tests as much as possible.

Why go to Fertilys if free screening tests exist elsewhere?

In Quebec, prenatal screening for trisomy 21 is available at no cost to all pregnant women. Two blood tests a few weeks apart are necessary to analyze proteins and hormones in the mothers blood. The compiled results determine the risks that the fetus will or will not have trisomy 21. The rate of effectiveness of this analysis is about 70%

At Fertilys, prenatal screening in the first trimester is not restricted to trisomy 21. In addition to other types of trisomy, the prenatal screening program at Fertilys allows us to identify certain serious physical deformities in the fetus early and to predict adverse events in pregnancy, such as preeclampsia, intrauterine fetal growth restriction and preterm labour. These adverse events in pregnancy are more frequent than trisomy; after screening, they can be prevented with an appropriate treatment and the pregnancy can be monitored more closely.

State-of-the-art screening tests at Fertilys.

At Fertilys, early prenatal screening helps detect:

  • Chromosomal abnormalities. During fertilization, the 23 chromosomes in the sperm merge with the 23 chromosomes in the egg to form a diploid cell (possessing two copies of each chromosome). Sometimes the egg or sperm contains an extra copy of a given chromosome. In most cases, it results in a spontaneous abortion before the 10th week of pregnancy. However, trisomies 21, 18 and 13 can be viable and present at birth, though not without serious physiological repercussions for the child.
  • Preeclampsia and other hypertensive disorders. This appears as the sudden development of high blood pressure in a woman between the 20th week and the end of the pregnancy. Preeclampsia affects from 2 to 5% of pregnant women. When not detected in time, this disorder may result in serious complications, with the risk of fetal and maternal death. Inducing labour is the only way to treat the mother, but it sometimes results in a premature birth. At Fertilys, in addition to ultrasound measures, we use other biochemical markers that increase the detection rate of preeclampsia. Early screening allows us to identify at-risk patients and to treat them with low-dose aspirin to prevent or delay the appearance of this condition.
  • Fetal structural abnormalities. With improvements in imaging techniques, it’s now increasingly possible to detect physical malformations of the fetus. These abnormalities include, anencephaly, defects in the abdominal wall, spine and limbs, and heart defects.
  • Miscarriage and intrauterine fetal death. Despite prenatal screening in the first trimester confirming the viability of the fetus, 1% of women will have a miscarriage and 0.4% will have an intrauterine fetal death after the 20th week of pregnancy. Although miscarriages cannot be prevented, foetal death can be after 20 weeks. A patient who has been identified as at-risk through prenatal screening at Fertilys can benefit from closer medical monitoring and therefore avoid the intrauterine death of the baby.
  • Intrauterine fetal growth restriction. Fetuses with intrauterine growth restriction are exposed to higher risks of morbidity and prenatal mortality. These risks can be considerably reduced when the condition is identified in the first trimester of the pregnancy.