The first screening for pregnancy is an exciting study for a future mother. It is aimed at identifying fetal malformations, anomalies. The results of the study can be deciphered only by the doctor who observes the pregnancy.
What is a trimester screening?
The first screening is a comprehensive examination of the fetus, which includes ultrasound and a biochemical study of the blood of a future mother. For the whole pregnancy this can be done thrice, 1 time per trimester. In most cases, only a scheduled ultrasound examination is mandatory. If the doctor suspects a violation, deviation from the norm, in addition, a biochemical blood test will be performed.
In order to obtain an objective result and correctly interpret the data, the doctor must take into account several parameters, such as height, weight of the pregnant woman, the presence of bad habits, which may affect the results of the study. With this in mind, the pregnant woman should not attempt to decipher the first screening performed during pregnancy on her own.
Why is screening for pregnancy necessary?
The screening of the first trimester allows for early stages of intrauterine development to identify possible deviations in the formation of internal organs, to detect genetic diseases. Among the main goals of such a comprehensive examination of a pregnant woman can be identified:
- elimination of ectopic pregnancy ;
- determination of the number of fetuses and the uterus;
- evaluation of the basic parameters of the fetal life - counting of heartbeats, listening to heart sounds;
- definition of physical parameters of infant development;
- anatomical examination of the fetus (detection of defects in development);
- The examination of the placenta and the identification of its dysfunction.
The first screening during pregnancy does not determine a specific disease in the fetus, but only points to typical signs of it, markers. The results obtained are the basis for further investigation, the assignment of additional laboratory studies. Only after receiving all the necessary information is a conclusion made, a diagnosis is made.
First screening for pregnancy - timing
In order to obtain objective results that allow for a correct evaluation of fetal development, screening should be carried out at a certain time. Terms of the first screening for pregnancy - the 1st day of the 10th week - the 6th day of the 13th week. Most studies are conducted at the 11-12th week of pregnancy, which are considered the best time.
Given this feature, the result and objectivity of the research directly depend on the correctness of the determination of the term. Doctors calculate it with the date of the last menstruation, its first day. Providing medical professionals with incorrect information about the time of the last months is fraught with a misinterpretation of the information received during the screening.
Biochemical Screening Trimester
This type of test for pregnant women in the first trimester is often referred to as a double test. This is due to the fact that during its implementation, the concentration in the blood of two parameters is established: free b-hCG and PAPP-A. HCG is a hormone that begins to be synthesized in the body of a future mother with the onset of conception. Its concentration increases daily and reaches its maximum by the 9th week. After this, there is a gradual decrease in hCG.
PAPP-A is a protein of the A-plasma, a protein structure by its nature. According to its content in the body, doctors establish a predisposition to the development of chromosomal abnormalities (Down syndrome, Edwards syndrome). In addition, the inconsistency of the PAPP-A level may indicate the following:
- fading of the fetus ;
- hypotrophy;
- pre-eclampsia .
Ultrasound, first trimester
Ultrasound in the first trimester is conducted no earlier than 11 obstetric weeks and it is later 14. The purpose of the survey is to establish the physical parameters of the child's development, the diagnosis of anomalies in the structure. Among the main parameters taken into account in ultrasound in the first trimester of pregnancy:
- KTP - coccyx-parietal size (distance from the parietal bone to the coccyx);
- Head circumference;
- BDP - biparietal size (distance between parietal tubercles);
- TVP - the thickness of the collar space;
- heart rate (heart rate);
- length of the shoulder, thigh, forearm, and lower leg;
- location of the heart, large blood vessels;
- location of the placenta, attachment site, thickness.
The first screening is how to prepare?
Before taking the tests in the first trimester of pregnancy, the expectant mother should clarify the doctor's principles of preparation for them. This will eliminate the receipt of an incorrect result and the need to re-pass the examination because of this. With regard to studies that include the first screening performed during pregnancy, the main ones are ultrasound and a biochemical blood test.
When the first screening is done, the ultrasound diagnostics included in it do not require any special preparation. All that needs to be done by a pregnant woman before going through a survey is to drink 1-1.5 liters of water without gas 1-2 hours before the procedure. After that, you can not go to the toilet. A filled bladder in this case helps to perfectly view the uterus, its cavity. In the case of a transvaginal study, this is not required.
Preparation for biochemical analysis is more thorough. For a few days a woman needs to follow a diet. On the day of the study, do not eat in the morning, and the day before, stop taking it at least 8 hours before the test. When preparing from a diet, doctors are strongly advised to delete:
- chocolate;
- seafood;
- fatty and meat dishes;
- citrus.
How is the first screening performed?
When the screening is carried out, the first trimester is already over. Before the implementation of this diagnostic complex, the doctor informs the pregnant woman in advance, tells her about the rules of preparation and the specifics of the implementation of each manipulation. The very procedure of ultrasound diagnosis does not differ from usual ultrasound. Often it is carried out transvaginally, in order to better examine the fetus. At the same time, high-resolution equipment is used, which helps to identify the sex of the child at the first screening.
A biochemical blood test, which includes the first screening during pregnancy, does not differ from conventional blood sampling. The material is taken from the ulnar vein in the morning on an empty stomach, transferred to a sterile tube, which is labeled and sent to the laboratory for analysis.
The first screening for pregnancy - the norm
After the first screening has been carried out, only the doctor should compare the results with the results obtained. He is aware of all the features of a particular pregnancy, the condition of the future mother, her anamnesis. These factors are necessarily taken into account when interpreting the results. In this case, doctors always make an amendment to the individual characteristics of the mother's body, so a slight deviation from the established norm is not considered a sign of violation.
Ultrasound in the first trimester of pregnancy - the norm
The short ultrasound (the first trimester of pregnancy) is aimed at diagnosing pathologies of fetal development. At its realization the doctor establishes parameters of physical development of the baby, which normally have the following values:
1. KTR:
- 10 weeks of pregnancy - 33-41 mm;
- 11 week - 42-50;
- 12-51-59;
- 13 to 62-73.
2. TVP:
- At 10 weeks - 1,5-2,2 mm;
- in 11 - from 1,6 to 2,4;
- in 12 - not less than 1.6 and not more than 2.5;
- in 13 - 1,7-2,7.
3. Heart rate (beats per minute):
- 10 weeks - 161-179;
- 11 - from 153 to 177;
- 12-150-174;
- 13-47-171.
4. BDP:
- 10 weeks - 14 mm;
- 11-17;
- 12 - 20;
- 13 weeks - 26.
Biochemical screening - norms of indicators
Biochemical screening of the trimester, decipherment of which is carried out by a doctor, helps to identify genetic pathologies in a baby on a very short time. Indicators of the norm of this study look like this:
1. hCG (mU / ml):
- 10-11 weeks of pregnancy - from 20,000 to 95,000;
- 12 weeks - 20000-90000;
- 13-14 - not less than 15,000 and not more than 60,000.
2. RAPP-A (MED / ml):
- 10 weeks - 0.45-3.73;
- 11 - 0.78-4.77;
- 12 -1.03-6.02;
- 13 - 1.47-8.55.
1st trimester screening - deviations
As already mentioned above, the deciphering of the first screening should be carried out only by a specialist. A future mother should not compare the results of the research with the norms. Evaluation should be carried out in a complex way - doctors never diagnose on the basis of screening alone, comparing the norms of the first screening of reality. However, it is possible to make assumptions about the presence of pathology. Elevated hCG indicates:
- genetic disorders - Down syndrome, Edwards , trisomy;
- diabetes;
- toxicosis .
Reduction in HCG concentration occurs when:
- ectopic pathology;
- risk of abortion.