Comprehensive diagnostics of the expectant mother’s body at an early stage of gestation.
It includes diagnostic procedures that allow you to assess the speed of intrauterine development of the baby by comparing the gestational age according to the protocols of the Ministry of Health of Ukraine.
The first trimester lasts from the 1st day of the final menstruation to the 13th week.
Screening in medicine means identifying risk groups of pregnant patients who may be indicated for additional testing.
Screening is performed on weeks 11-13 + 6 of pregnancy.
The first stage is fetal ultrasound.
It gives the obstetrician-gynecologist the opportunity to establish the risk of developing possible abnormalities, identify a predisposition to genetic diseases, and draw up a general picture of the health of the expectant mother.
During the examination, specialists carefully study the morphological parameters of the fetus in comparison with their current gestational age. The doctor also measures the length of the cervix.
2 methods of ultrasound diagnostics of the first trimester:
- transabdominally (through the abdomen)
- transvaginally (insertion of the transducer into the vagina).
6 anthropometric parameters of the fetus are studied
What parameters of the unborn baby are examined on ultrasound?
- Fetal size from crown to tailbone
- Length The size of the baby’s body from the crown to the heels
- BPR (Biparietal size) is the distance between the dark tubercles
- TCP thickness of the collar space
- HR heart rate heart rate
- Head circumference
Normal values of fetal ultrasound diagnostics at different gestational ages
| The week of pregnancy | CTR, mm | TFP, mm | Nasal bone, mm | Heart rate, beats per minute | BPR, mm |
| 11 | 42-50 | 1,6-2,4 | visible | 153-177 | 17 |
| 12 | 51-59 | 1,6-2,5 | more than 3 | 150-174 | 20 |
| 13 | 62-73 | 1.7-2,7 | more than 3 | 147-171 | 26 |
Second stage: biochemical blood test of a pregnant woman in the 1st trimester
- It is prescribed in case of deviations from the reference values of fetal ultrasound diagnostics and is performed at certain gestational ages, since the reference values depend on the gestational age.
- HCG chorionic gonadotropin is a hormone produced in amniotic fluid that is used to diagnose pregnancy.
- PAPP-A protein-A is a protein produced by the placenta, which is responsible for the normal functioning of the latter.
Reference values of hCG levels at different gestational ages in the 1st trimester
| Weeks of pregnancy | β-HCG, ng/ml | A higher than normal hCG level may indicate: | Decreased hCG may indicate: |
| 11 | 17,4-130,3 |
|
|
| 12 | 13,4-128,5 | ||
| 13 | 14,2-114,8 |
Reference values of PAPP-A levels at different stages of pregnancy in the 1st trimester
| Weeks of pregnancy | PAPP-A, U/mL | Deviation from the reference values |
| 11 | 0,78-4,77 | With a decrease, the risk of fetal development increases:
|
| 12 | 1,03-6,02 | |
| 13 | 1,47-8,55 |
Preparing for the first trimester screening
To ensure that the results of ultrasound and biochemical blood test are as objective as possible, doctors strongly recommend following the preparation recommendations:
- Dietary regimen: exclude chocolate products, seafood and citrus fruits, fried and fatty foods from the diet.
- It is not recommended to eat 12 hours before the biochemical blood test.
- When performing transabdominal ultrasound, it is necessary to fill the bladder.
