Now, during pregnancy, a woman does a lot of research. One of them is the first trimester screening, which allows us to suspect serious pathologies of the fetus and pregnancy. However, a woman needs to understand that the results of this study are not a sentence.
Therefore, if the result of screening for Down syndrome is positive, do not despair and get upset. This does not mean that the baby will be born with this pathology, but the probability is higher than that of others.
The first trimester screening includes ultrasound and the so-called “double test”. The optimal time for it is considered to be from 10 to 13 weeks. First you need to do an ultrasound to determine the number of fruits, their size, gestational age.
And then biochemical screening of the first trimester is carried out, which consists of analyzes for PAPP-A and b-hCG. The concentration of these markers in the blood of the expectant mother in combination with ultrasound data allows us to identify the likelihood of chromosomal pathologies in the baby.
In order for the result to be reliable, it is necessary to indicate weight, age, ethnicity, as well as whether a woman suffers from diabetes and whether she smokes. If the baby was conceived using IVF, then this should also be noted.
First trimester screening is performed to assess the likelihood of the baby having Edwards syndrome, Down syndrome, neural tube defect. Indications for its implementation are:
- harmful effects on parents, such as radiation;
- hereditary diseases in relatives;
- the presence of a child with chromosomal abnormalities and malformations , including the fetus during an interrupted pregnancy.
However, today gynecologists recommend undergoing this study to absolutely all pregnant women. In addition, in many women's consultations it is carried out absolutely free of charge.
Today, reference values are often adjusted based on individual data. Apply MoM calculation to analyze the results. This is the ratio of the data obtained in the study to the individual median values.
Such an integrated approach increases the reliability of screening. It helps to determine Down syndrome in 1 trimester in 90% of cases, however, while 5% of the results are false positive. Also, the reliability of the study may be affected by the use of certain drugs, especially hormones.
In addition, a decrease and increase in the level of PAPP-A and b-hCG may occur in conditions that are not associated with chromosomal abnormalities. Among them, intrauterine infections, maternal diseases, obstetric complications.
Analysis of the results should be carried out by a qualified specialist. Nevertheless, looking at them some assumptions, not a doctor can make.
According to the results of ultrasound, the thickness of the collar space should be no more than the norm of 2.6 mm. The nasal bone in the fetus at this time should be visualized, otherwise there is a risk of chromosomal abnormalities.
The normal concentration of b-hCG is in the range of 14.3-130.5 ng / ml. If it is less, then there is a risk that the fetus has Edwards syndrome, especially if the level of PAPP-A is also low.
If the concentration is more than 2 times higher than normal, then you can suspect Down syndrome in a baby. Especially if at the same time the concentration of PAPP-A is less than required and the results of ultrasound are not comforting. Extremely low values of these markers may indicate a halt in fetal development.
At a level of PAPP-A, the Shereshevsky-Turner, Corneli de Lange syndromes may be less than normal. In addition, defects in implantation of the embryo and formation of the placenta are possible, which will manifest later.
These pathologies can lead to hypertensive complications, nephropathy, preterm birth, missed pregnancy, fetal hypoxia. Such women should be monitored, more research and therapy are needed.
Corrected MoM values are also important. They should be above 0.6 and less than 2. Pregnancy requires observation with a PAPP-A MoM below 0.5.
Thus, the first trimester screening is an important study that allows to detect chromosomal abnormalities in the fetus, as well as possible pregnancy pathologies. It consists of an ultrasound scan, which is performed first, and analyzes on PAPP-A and b-hCG. The results of the study are not the final diagnosis, but only an estimate of the probability.