Prenatal diagnostics

Prenatal diagnostics – general information

The following methods of prenatal diagnostics are offered as a standard part of modern prenatal care.

The main aim of these methods - and especially of their combination - is to give you the highest possible probability of giving birth to a healthy newborn and a minimal risk of stressful surprises after delivery.

However, no prenatal diagnostic method is able to provide a 100% guarantee of perfect fetal health.

We are aware of the controversies surrounding the safety / risk of obstetrical ultrasound.The way our office uses ultrasound minimizes its risk and brings the most benefits to both you and your baby.

We are also aware that some of these methods can have false positive or false negative results and can cause a certain level of emotional stress. We do, however, believe that the rare odd result of some of the following tests is much less stressful than the birth of a genetically or morphologically handicapped baby.

Pregnancy can give you unforgettable feelings of happiness and pleasure even if you from time to time do not feel great. The chance to watch the growth and development of your baby belongs to the most precious moments.

The main tests are:

- standard – offered to every woman
(mostly non-invasive)
- non-standard – offered to a certain group of women
(mostly invasive)

Take a look at the review of prenatal diagnostic methods and decide with your doctor which ones you wish to have performed.

Standard methods of prenatal diagnostics

1. Nuchal translucence measurement + nasal bone visualisation

Ultrasound measurement of the thickening on the baby´s neck. Ideal timing: week 13/14.
This US method is based on the fact that about 70% of Down fetuses have significant
swelling on their necks caused by liquid cumulation. The test can reveal about 75%
chromosomal abnormalities (mainly Down´s syndrome), false positivity 5%.
Presence of the nasal bone is another good marker of fetal genetic health.

2. Determination of PAPP-A and free beta-hCG

Determination of two plasmatic proteins – possible markers of fetal abnormalities
(PAPP-A: Pregnancy-Associated plasma protein A, free beta subunit of human chorionic
gonadotropin) . Ideal timing: week 10+0 up to 11+3.
The test results combined with measurement of nuchal translucence and nasal bone can
reveal 87% fetuses with Down´s syndrome, false positivity 5%.

3. Triple screen = triple test

The test determines level of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG)
and estriol (E 3)in the maternal blood and their ratio taking into account a patient´s weight,
age and pregnancy length. The AFP level is related to neural tube defects (spine and brain),
the hCG level monitors the risk of Down syndrome and the estriol level is linked to
general pregnancy outcome. Ideal timing: week 16-18.
The triple test can reveal about 65% of all genetic abnormalities.

4. Detailed obstetrical sonography in 2nd trimester or„organ USG“

The following organs are visualised and evaluated: heart (4 chambers,great vessels), diaphragma, stomach, kidneys and bladder, spine, anterior abdominal wall, umbilical cord, brain, face, four extremities. Also fetal behavior, location / quality of placenta and amniotic fluid volume are evaluated. This sonography is performed in second trimester, week 20-22.

Extended methods of prenatal diagnostics

1. Non-invasive methods: Fetal echocardiography

Detail ultrasound of fetal heart performed in week 21-22 by a fetal echocardiography specialist. This specialised ultrasound examination is reserved for women who have heart defect in personal or family history, women over 35 years and with positive triple test who prefer non-invasive methods of prenatal diagnostics (based on the high incidence of heart defects in fetuses with Down syndrome).

2. Invasive methods: Amniocentesis (AC)

Amniocentesis is the sampling of amniotic fluid for the purpose of chromosomal and biochemical analysis of amniotic fluid (=water). Amniocentesis can reveal abnormalities as to the number and structure of chromosomes (important monitoring of chromosomal inborn defects – e.g. Down´s syndrome, etc) and some other diseases of fetus.
AC is usually performed transabdominally – an ultrathin needle is inserted into the amniotic sac under ultrasound control, 20 ml of amniotic fluid is obtained and used for analysis.
The results are available within two weeks after the procedure.
The overall risk of complications connected with the procedure is 0.5 %.
The most common method of invasive prenatal diagnostics used in the Czech Republic.