For sure, every pregnant woman has heard about different kinds of examinations, which allow to identify possible genetic deviations in the child. Someone conducts such analyzes voluntarily, wanting to protect themselves, and to someone they are appointed as a mandatory procedure. Biochemical screening is one such survey. It consists in the ultrasound examination of the fetus (for visual detection of possible abnormalities, measurement of the nasal bone and collar zone) and analysis of the venous blood of the mother (for determining the level of the pregnancy hormone, estriol and fetal A-globulin). That is why the first screening, on what week it was conducted, is called double. If you do not know how many weeks the first screening is done, be sure to check with your gynecologist.
When to do the first screening?
So, your pregnancy has already become noticeable, and you want to know on what term the first screening is? This is correct, because much depends on this analysis.
Answering the question of how much the first screening is done, doctors usually disagree, appointing this examination on the eleventh, twelfth or thirteenth week. An obligatory condition for carrying out this test is the most accurate determination of the gestational age, since every seven days all the parameters taken into account when deciphering the test results are changed.
In some cases, when the first screening is carried out, laboratory workers request ultrasound results so that all calculations are performed correctly. Both the overestimated and underestimated results of the double test should be alerted. For example, lowering the hormone level of pregnancy can talk about ectopic pregnancy, delay in fetal development, chronic placental insufficiency, whereas its increase indicates a multiple pregnancy, diabetes maternal, gestosis (that is, the release of protein in the urine), various pathologies of the fetus, including chromosomal (Patau, Down or Evards syndrome). Much attention is also paid to the analysis of the functioning and location of the placenta, the study of the tone of the uterus, the state of the ovaries.
Remember that the results of a double test can only be trusted by 85%, and therefore, if the doctor suggests aborting the pregnancy, you need to double-check everything and then make a decision.