What is prenatal testing?

Prenatal testing is a procedure recommended to pregnant women and consists of a set of diagnostic and screening tests. The set of these tests is performed before birth and is aimed at detecting serious diseases of the foetus, affecting the body or the brain.  

Types of prenatal tests

The tests which are included in the prenatal process are divided into screening and diagnostic tests. For example, the nuchal translucency measurement is a screening test aiming at detecting possible birth defects, such as Down syndrome. Diagnostic tests are based on the analysis of the genital material of the foetus and are performed if there is suspicion of serious disease.

The vision of the people of the department of prenatal testing

The prenatal examination department of St. Luke's Hospital belongs to the same department as that of obstetrics. The purpose of the people of the department is to contribute to the improvement of the quality of health provided to pregnant women, as well as to the well-being of their foetuses. Ultrasounds are performed according to the highest standards and are supported with detailed information and counselling.

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Prenatal examination ultrasounds at St. Luke's Hospital.

The prenatal examination ultrasounds performed at the Hospital are:

• Viability
  
• Nuchal translucency (11-14 weeks)
• B' level (20-24 weeks)
• Doppler and growth (24-40 weeks)
• Cervix length
• Foetal echocardiography
• Gynaecological 2D ultrasound

Main invasive prenatal procedures at St. Luke's Hospital

The main invasive prenatal testing procedures performed at the Hospital are:

Viability ultrasound

It is performed transvaginally at the 6th - 10th week of gestation, in order to determine the number of embryos, the chorionicity and whether the pregnancy develops normally within the uterus.

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First trimester - nuchal translucency (11-14 weeks)

The examination is usually performed transabdominally, but in some cases it may be necessary for the examination to be performed transvaginally. The reasons for this examination are:

• The accurate estimation of the gestational age.
• Diagnosis of multiple pregnancy.
• Diagnosis of significant abnormalities of the foetus or early negative cardiac function.
• To assess the risk of down syndrome, as well as other chromosomal abnormalities, by taking into account its biochemical markers (β-HCG and PAPP-A).
• The measurement of the flow in the mother's uterine arteries to assess the occurrence of preeclampsia and foetal development in the third trimester of pregnancy.

B' level (20-24 weeks)

This is a detailed ultrasound, where we examine the anatomy of the foetus, perform accurate biometry in order to assess its development, determine the location of the placenta and estimate the amount of amniotic fluid. Particular attention is paid to the brain, face, spine, heart, stomach, intestine, kidneys and limbs.

In addition, we measure blood flow in the mother's uterine arteries to assess the risk of preeclampsia and intrauterine development.

Development and Doppler > 24 weeks

It aims to calculate the development and well-being of the foetus by measuring the head, abdomen and length of the femur of the foetus. Also, the flow of blood to the placenta and foetus is evaluated and the activity of the foetus is examined. Other processes are some of the following:

• Measurement of the amount of amniotic fluid.
• Evaluation of the location and appearance of the placenta.
• Estimation of data of the anatomy of the foetus.

It is recommended to be performed on all pregnant women, but especially on those who are at high risk, such as women with:

• Risk of preeclampsia
• Hypertension
• Slow development of the foetus
• Type 1 or 2 diabetes mellitus
• Gestational diabetes mellitus
• History of intrauterine foetal death or an anatomical abnormality that became visible in the third trimester of pregnancy

Estimation of the length of the cervix

It is performed transvaginally mainly during the B' level ultrasound. It is recommended to all pregnant women to assess the length of the cervix and consequently the possibility of preterm birth (multiple pregnancies, women with a history of preterm birth, vaginal bleeding, assessment of the location of the placenta, congenital abnormalities of the uterus and cervix).

Gynaecological ultrasound

It can provide us with answers to a variety of gynaecological diseases of the female internal genital organs.

Trophoblast/chorionic villi biopsy, (CVS – Chorionic Villus Sample)

Trophoblast biopsy is the examination of the tissue of the placenta. Both the foetus and the placenta come from the same fertilized egg and so the chromosomes present in the cells of the placenta are the same as those of the foetus. Consequently, it can be checked if the foetus has a genetic or chromosomal condition.

Amniocentesis

Amniocentesis involves the examination of cells in the fluid surrounding the foetus (amniotic fluid). The cells in the amniotic fluid come from the foetus, and so the chromosomes present in these cells are the same as those of the foetus. Thus, we can check if the foetus has a genetic or chromosomal condition.

When is trophoblast biopsy or amniocentesis recommended?

Trophoblast biopsy or amniocentesis are not recommended in all pregnant women. They are recommended only if there is a high risk that the foetus has a genetic or chromosomal condition.

What diseases can they identify?

• Syndromes such as Down (trisomy 21), Edwards (trisomy 18), and Patau (trisomy 13)
• Thalassemia
  
• Sickle cell anaemia
• Cystic fibrosis
• Phenylketonuria
• Duchenne muscular dystrophy
• Many other genetic syndromes

What are the risks associated with the test?

The risk of miscarriage for both methods is about 0.2-0.5%. If a miscarriage is to occur due to the examination, this will happen within the next three days.

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