Pregnancy examinations and tests

Prenatal screening

Prenatal screening aims to identify pregnancies with an increased risk of chromosomal conditions such as trisomy 13, 18 or 21.

At our hospital, first trimester screening includes the OSCAR (One Stop Clinic for Assessment of Risk) test. Between 11 and 12 weeks of pregnancy, a blood test is performed. This is followed by an ultrasound scan between 11 and 14 weeks.

During the first trimester ultrasound:

• the size of the pregnancy is confirmed
• foetal anatomy, amniotic fluid volume, and placental structure and position are assessed
• the nuchal translucency (fluid at the back of the baby’s neck) and other markers associated with chromosomal conditions are measured

The results of the blood test and ultrasound are combined to calculate the estimated risk of a chromosomal condition. The risk is expressed as a ratio.

Please note: a higher-risk result does not mean that your baby has a chromosomal condition. It indicates an increased probability.

If screening suggests an increased risk, further tests may be offered.

These may include NIPT Invasive Procedure. Non-invasive prenatal testing, or NIPT (Non-invasive Prenatal Testing), is a highly sensitive test for the detection of chromosomal diseases.

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Fetal chromosome testing

To carry out foetal chromosome testing, it is necessary to obtain cells of foetal origin. This is done through either chorionic villus sampling or amniocentesis.

Chorionic Villus Sampling (CVS)

Chorionic villus sampling involves taking a small sample of tissue from the developing placenta. It is usually performed between 11 and 14 weeks of pregnancy. Before the procedure, an ultrasound scan is carried out to confirm the duration of pregnancy, the number of foetuses, the position of the foetus, the heart rate, the amount of amniotic fluid and the location of the placenta.

Before the procedure, the abdomen is cleaned, and sterile equipment is used throughout the procedure.

The sample is taken under continuous ultrasound guidance. Local anaesthetic (lidocaine) is used to minimise discomfort.

After the procedure, you may experience mild abdominal cramping or light vaginal spotting. In most cases, these symptoms settle within a few days.

Amniocentesis

Amniocentesis involves taking a small sample of amniotic fluid, which contains foetal cells. The procedure is usually performed between 15 and 19 weeks of pregnancy.

As with chorionic villus sampling, an ultrasound scan is carried out beforehand to determine the duration of pregnancy, the number of foetuses, the position of the foetus, the heart rate, the amount of amniotic fluid and the location of the placenta.

Before the procedure, the woman's abdomen is cleaned. Under ultrasound guidance, a fine needle is inserted through the abdomen to withdraw approximately 15–20 ml of amniotic fluid. The discomfort is usually similar to having a blood test, and pain relief is not normally required.

After the procedure, there may be menstrual-like pain in the lower abdomen, which in most cases disappears on its own.

Preliminary results are often available within a few days. Final results typically take 2–3 weeks.

Depending on the reason for testing, additional analyses may include:

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Preeclampsia screening

Hypertensive disorders are one of the most common health problems during pregnancy. Among premature births, one in five cases is caused by preeclampsia or hypertension. Preeclampsia is a pregnancy complication that manifests itself in the second half of pregnancy.

In most cases, with preeclampsia, there is an increase in blood pressure. This is accompanied by symptoms indicating a disruption in the function of other organs, such as protein in the urine, persistent headache, visual disturbances, and pain in the upper abdomen. It is known that preeclampsia begins with a disruption in the development of the placenta in the first trimester of pregnancy.

If acetylsalicylic acid is taken in low doses at an early stage of the development of the placenta, then it is possible to prevent the development of preeclampsia or delay the manifestation of the disease, as well as reduce the problems caused by premature birth. For this reason, risk assessment is carried out between 11 and 14 weeks of pregnancy to identify women who may benefit from preventive treatment.

Risk assessment is combined with first trimester screening and includes: maternal age, height, weight, race, smoking status, mean arterial blood pressure, placental growth factor (PLGF) measured in blood serum and uterine artery blood flow assessed by ultrasound.

This combined assessment can identify approximately 90% of early-onset preeclampsia cases (before 34 weeks). If a higher risk is identified, low-dose aspirin (150 mg) is recommended in the evening until 36 weeks of pregnancy.

Studies, including the ASPRE trial, have shown that this approach significantly reduces the risk of early preeclampsia. It was found that taking acetylsalicylic acid in a prophylactic dose reduced the risk of preeclampsia before week 34 by 82%. For early prediction of preeclampsia, we use a combined test in the first trimester of pregnancy, 11-13 weeks. Risk assessment is carried out at the first trimester screening with the calculation of the risks of chromosomal diseases.

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Second trimester screening (foetal anatomy scan)

The second trimester ultrasound scan is carried out between 19 and 22 weeks of pregnancy. The purpose of the scan is to specify the duration of pregnancy (if it has not been done in previous scans), assess the amount of amniotic fluid, placenta, foetal growth and anatomical structures, and detect congenital abnormalities.

If abnormalities are identified, further genetic testing may be offered and consultation with specialist teams arranged. We work closely with the Tartu University Hospital and Tallinn Children's Hospital.

In collaboration with Tallinn Children's Hospital, multidisciplinary team discussions ensure that each pregnancy is managed according to the most appropriate care plan, including planning for delivery and postnatal care.

If specialised treatment is not available in Estonia, referral to European foetal medicine centres may be arranged, with funding provided by the Health Insurance Fund where appropriate.

In cases where specialised treatment is required, we cooperate with several European centres: