Every pregnant woman worries about the health of the unborn baby. Currently, there is prenatal screening that helps identify the likelihood of congenital diseases. This examination also includes an analysis called the “genetic deuce”. What does such a test show? We will consider this question further.
What is this analysis
Genetic deuce is an analysis of a pregnant woman’s venous blood for possible chromosomal abnormalities in an unborn baby. This study is otherwise called biochemical screening, it must be done at an obstetric period of 11 - 13 weeks.
First, the patient undergoes an ultrasound scan. Using this study, the size of the cervical fold in the embryo and the condition of the bones of the nose are determined. If deviations are noted in these indicators, then this may indicate a possible Down syndrome in the unborn child.
Then the woman takes blood for analysis. In laboratory conditions, the level of the beta subunit of chorionic gonadotropin (beta-hCG) and plasma protein A associated with pregnancy (PAPP-A) is determined. These indicators are markers of the risk of genetic mutations.
Markers
What are these markers? Chorionic gonadotropin is produced in the body of a woman from early pregnancy. It is produced by the placenta. The molecule of this hormone contains a beta subunit, which has a biological effect on the body. Therefore, it is determined in the analysis.
PAPP-A is a protein that is produced in large quantities during the gestation period. It is produced by the outer layer of the embryo when introduced into the uterus.
What analysis shows
What does the genetic deuce show? It is important to remember that deviations in the results of this analysis do not indicate 100% of the pathology of the fetus. Such a study speaks only of the degree of probability of possible genetic mutations.
Using this analysis, you can identify the risk of chromosomal syndromes: Down; Cornelia de Lange, Edwards.
In addition, deviations in the results of the genetic deuce can talk about toxicosis, the threat of miscarriage, cessation of fetal development, placental pathologies, as well as diabetes in the mother.
It is very important to remember that the analysis gives reliable results no later than 13 weeks of pregnancy. It is during this period that he can show the likelihood of developing chromosomal diseases. At a later date, the results of such screening will be unreliable.
Indications
Genetic deuce is not a mandatory analysis. However, obstetrician-gynecologists strongly recommend that women undergo biochemical screening. With deviations in the indicators of the genetic deuce, a more detailed study will be required. This will help to track genetic mutations in the fetus on time.
In some cases, such an analysis is prescribed without fail:
- When the patient is older than 35 years.
- If a woman already has a child suffering from chromosomal pathologies.
- If the patient has relatives with genetic mutations.
- If a woman shortly after conception suffered from rubella, herpes, cytomegalovirus or hepatitis.
- If the patient has previously had a pregnancy pathology or miscarriage.
Study preparation
Particular attention should be paid to preparing for the study. Otherwise, the analysis may give false results. Women very often worry before screening, and deviations in rates can cause serious stress. And emotional experiences during pregnancy are extremely undesirable.
To ensure that the analysis indicators are reliable, doctors advise to comply with the following recommendations:
- The analysis is taken strictly on an empty stomach. Before the study, it is not recommended not only to eat, but also to drink water.
- A few days before the test, you need to follow a special diet. You must stop eating citrus fruits, seafood, nuts, chocolate, as well as fatty and spicy foods.
It is very important to adhere to these rules. After all, any deviation in nutrition on the eve of the study can lead to incorrect results.
Norm
When calculating the results of the study, the doctor uses a special program. All indicators of biochemical screening are introduced into it. The program builds a graph of deviations of these data from the norm. In this case, the MoM coefficient (multiple of median) is calculated.
The norm of the genetic deuce is considered to be MoM from 0.5 to 2.5. The patient is given a form on which the following data is indicated:
- risks associated with a woman's age;
- values of beta-hCG and PAPP-A;
- risks of genetic mutations;
- MoM coefficient.
Normal beta-hCG values are from 13.4 to 130.4 ng / ml, and PAPP-A is from 0.79 to 8.54 mU / ml. The exact reference values of the markers depend on the gestational age.
It is very important to undergo biochemical screening on time. In the second trimester, PAPP-A returns to normal even if the fetus has mutations.
Decryption
When decoding the genetic deuce, you need to pay attention to each indicator. An increase in beta-hCG may indicate a risk of Down syndrome in the fetus. It can also be a sign of toxicosis or diabetes in the mother. If increased beta-hCG is noted during multiple pregnancy, then this usually does not indicate pathology.
Low beta-hCG may indicate a possible Edwards syndrome in the embryo, placental insufficiency or the threat of termination of pregnancy.
Reduced PAPP-A is noted with a risk of chromosomal syndromes (Down, Cornelia de Lange, Edwards), as well as with malnutrition of the embryo.
A high level of this protein may indicate a low location of the placenta, as well as a large weight of the embryo.
It should be remembered that only a doctor can deal with a detailed decoding of the indicators of a genetic deuce. This takes into account not only the values of beta-hCG and PAPP-A, but also their ratio, as well as the results of ultrasound. Correctly interpret the research data can only be a specialist.
What to do in case of deviations from the norm
What to do if a genetic deuce shows the likelihood of chromosomal diseases in a baby? First of all, do not panic and make a hasty decision to terminate the pregnancy. It should be remembered that biochemical screening only indicates a possible risk of genetic abnormalities.
If there are deviations from the norm in the screening, the doctor directs the patient to a more detailed diagnosis. In the early stages of pregnancy, amniotic fluid analysis (amniocentesis) or a chorionic villus examination are performed. These are invasive procedures that should only be done if there is a serious suspicion of fetal chromosomal abnormalities.
With amniocentesis, a puncture is made in the abdominal wall or posterior vaginal fornix and amniotic fluid is taken for examination. This study reveals chromosomal abnormalities with a probability of 99.5%.
In the study of chorionic villi, the material is taken through a puncture in the abdominal wall or a catheter, which is inserted into the cervix. Such an analysis reveals more than 3,000 possible diseases in the fetus. The reliability of the results is 99%.
Unfortunately, many women refuse to undergo biochemical screening. They are afraid to hear about the poor result of the study. However, every pregnant woman needs to undergo such an analysis. After all, it is better to learn in the early stages about the possible risk of chromosomal diseases and undergo additional examinations. In addition, the results of screening are not always confirmed by amniocentesis or the study of chorionic villi.