Nuchal translucency Test
This ultrasound gets carried out in the pregnancy between 11 weeks and 3 days and 13 weeks and 6 days (CRL 45mm – 84mm). It is usually carried out through the abdomen, but in some cases it may be necessary for the examination to be performed via the vagina. It is the most important ultrasound examination in the pregnancy.
The exact age of pregnancy gets determined
This is especially important for women who cannot remember the date of their last period, have irregular menstruation, or have conceived while breast-feeding or immediately after discontinuing a contraceptive tablet. We measure the size of the fetus and from this we calculate the probable date of birth (WHO – 40 weeks).
Diagnosis of some major congenital abnormalities
Significant abnormalities may be visible at this gestational age, but the 20-week ultrasound is necessary.
Multiple pregnancy diagnosis
About 2% of natural conceptions and 10% of IVF conceptions lead to multiple pregnancies. This ultrasound can determine whether both embryos develop normally and whether babies share the same placenta, which can lead to pregnancy problems. In such cases, it would be advisable to monitor pregnancy more closely.
Diagnosis of premature pregnancy failure (miscarriage)
Unfortunately, 2% of women who are having the nuchal translucency test get the diagnosis of missed miscarriage, often several weeks before the test and without any warning. Couples will receive full advice on the possible causes of this problem and the options for the next actions and precautions that might be needed.
Calculation of the risk of preterm birth
The risk of preterm birth (before 37 weeks) can be assessed by measuring the cervical length. It is recommended to all pregnant women, but especially in cases of increased risk for preterm birth, such as multiple pregnancies, previous preterm birth history, congenital uterine abnormalities, history of cervical interventions (LLETZ, cone biopsy) and conditions such as maternal connective tissue / collagen diseases.
Cervical length is being measured via the vagina and it is recommended to repeat the measurement during the pregnancy time period between 20 and 22 weeks.
Calculation of the risk for slowdown of the fetal development due to endometrial problems /preeclampsia
Each exam includes the uterine artery flow assessment in combination with biochemical markers, such as PAPP-A and PLGF and takes into account the risk of slowdown of the fetal development. This slowdown can be mainly observed in the third trimester, when more Doppler ultrasounds get scheduled at the beginning of the third trimester, starting from 28 weeks of gestation.
Risk assessment for Down syndrome and other chromosomal abnormalities
Each woman should receive an assessment of her individual risk during her pregnancy. This is calculated by taking into account maternal age, measurements of hormones in the mother’s blood and ultrasound indicators, such as nuchal translucency, nasal bone, blood flow through the fetal heart and the fetal liver. Parents will receive full advice on the significance of this risk and the various options for further testing, such as invasive or cell free DNA testing.
Definition of Nuchal Translucency
Nuchal translucency is the ultrasound appearance of subcutaneous accumulated fluid behind the fetal neck during the first trimester of pregnancy in all embryos. The size of fetal nuchal translucency increases normally with gestational age (fetal length – CRL). The greater the nuchal translucency measurement gets, the greater the risk of chromosomal and structural abnormalities in the fetus becomes.
| Nuchal Translucency | Chromosomal Abnormalities | Fetal Death | Major Anomalies | Cardiovascular Anomalies | Healthy neonates |
|---|---|---|---|---|---|
| <95th | 0.2% | 1% | 1.5% | 0.3% | 97% |
| 95th-99th | 3.5% | 1% | 2.5% | 0.5% | 93% |
| 3.5-4.4mm | 20% | 2.5% | 10% | 3% | 70% |
| 4.5- 5.4mm | 33% | 3.5% | 20% | 6.5% | 50% |
| 5.5- 6.4mm | 50% | 10% | 25% | 10% | 30% |