A future mother, bearing a baby, always hopes for a safe pregnancy. But her expectations are not always met. At present, the abnormal development of the fetus is very frequent. For example, serious deviations from development, such as Down Syndrome, Turner Syndrome, Noonan Syndrome and many other chromosomal pathologies can be detected in early pregnancy.
The main methodology for detecting deviations in the development of the baby is to perform the first and second screening. Many experts insist that the latter is more informative.
Let's take a closer look at what this procedure is, and dwell in more detail on the very concept of the second screening during pregnancy, what week it is advisable to undergo, and is there any sense in this manipulation.
Screening: the essence of the examination of pregnant women
A targeted examination of the female body during pregnancy in medical practice is called screening. If this, as noted, is a focused procedure, then it is necessary to tell what exactly is being investigated and why.
Screening is done two or three times throughout pregnancy. The first (during the first trimester of pregnancy - 8-10 weeks) involves a complete medical examination:
- weighing;
- blood pressure measurement;
- tests: blood, urine;
- determination of blood group and Rh factor;
- testing for HIV infection and other infectious diseases (hepatitis, STDs, tuberculosis);
- intrauterine ultrasound examination;
- collection of information on hereditary, genetic diseases.
Based on indicators of a woman’s health status, specialists often recommend a future mother to undergo a second screening. This refers to examination during the second trimester of pregnancy (15-20 weeks). Important indicators at this stage are:
- ultrasound results;
- venous blood tests;
- hormonal panel.
A third screening is performed during the third trimester of pregnancy (30-35 weeks). At this stage, the results of ultrasound and dopplerography are important.
Screening gives the specialist who monitors the patient’s pregnancy a complete picture of the development of the fetus and changes in the health of the expectant mother. Identifies the risks of possible deviations or their presence.
What you need to know!
Screening is not a therapeutic procedure, the examination only allows you to monitor the development of the fetus after conception. Pregnancy is not always standard. There are cases when experts recommend termination of pregnancy at certain dates due to the identification of serious abnormalities in the development of the fetus. But there are many such situations when it is possible to bear a baby, even with discovered physical and genetic problems. The decision to give birth always remains with future parents.
It should be understood that:
- neither the parents themselves nor the doctors can influence the development of pathologies - in many cases the process is irreversible;
- children born with chromosomal diseases are deprived of a full life and require constant monitoring;
- Despite the availability of modern research methods, it is not always possible to make the correct diagnosis, therefore, in some controversial situations, the course of pregnancy is monitored over three trimesters.
Where are pregnant women screened?
Examination of pregnant women is carried out in the antenatal clinic at the place of residence, where the expectant mother applies for registration. The leading specialist appoints the patient a certain list of examinations and writes out a referral to medical centers or medical rooms. There she can take tests and get results with which she subsequently comes to visit her doctor.
After examining the results, the doctor decides:
- further observation of the patient;
- monitoring her condition and fetal development;
- preservation of pregnancy or its termination.
Mandatory Screening Schedule
There is no exact schedule for screening. For each pregnant woman, the period is individual. Therefore, when searching for the answer to the question, how many weeks do the second screening, you can only get information that the procedures are feasible during the second trimester.
This period allows us to evaluate not only the results of biochemical parameters, but also the anatomical structure of the fetus.
How many weeks of pregnancy do they have a second screening?
The second stage of examinations is appointed after the first. Many women have certain indications for a second screening. How many weeks is better to do this procedure, the observing doctor himself suggests. We emphasize that in most cases there are grounds for passing the second screening.
The clarity of the examination results depends on what week the second screening is carried out during pregnancy. Approximate dates - for 15-20 weeks. The results, for example, obtained at week 15, will differ from the responses received at 20. The development of the fetus depends on many social and hereditary factors, therefore, recommendations on the timing of screening are averaged.
A detailed description of the stages of the second screening
Regardless of how many weeks a second screening is done, an interval of 15-20 weeks is taken as a basis, the list of prescribed procedures is as follows:
- biochemical blood test - blood is taken from a vein and examined for hormones and protein;
- non-invasive blood test - isolation of fetal DNA and its study for the presence of chromosomal abnormalities;
- ultrasound examination of the anatomy of the fetus, the amount of amniotic fluid, the state of the placenta.
In the presence of any deviations identified as a result of the above procedures, the passage of the pregnant woman is recommended:
- cordocentesis - cord blood sampling;
- amniocentesis - amniotic fluid withdrawal.
These two procedures are accompanied by a high risk indicator and can cause an abortion, miscarriage and cause premature labor. Therefore, they are prescribed only in exceptional cases, performed only with the consent of the future mother in childbirth. This is also emphasized by the responses to the question, how many weeks do a second screening during pregnancy.
What deviations can screening in the second term of pregnancy show?
Specialists, when they conduct a second screening during pregnancy, can identify such pathologies and abnormalities of the fetus, such as:
- Down syndrome;
- Patau syndrome;
- Edwards syndrome;
- cystic fibrosis;
- galactosemia;
- hypothyroidism;
- non-molar triplody;
- phenylketonuria;
- galactosemia;
- anatomical pathologies and other abnormalities.
Can I refuse screening?
Of course, parents are responsible for the health of the future baby. Observation of the fetus is recommended for all women, regardless of health indicators. The second screening is very important during pregnancy! When conducting a survey in the second trimester, specialists can detect many deviations that could not be determined in the first stages.
Every woman in labor has the right to refuse additional examinations. But we must not forget that in this case, the risks of giving birth to an inferiorly developed child and the deterioration of the health of the future mother increase.
Refusal of research is only relevant if the health indicators of the expectant mother are normal. In this situation, only ultrasound is recommended for women without additional manipulations.
What are the indications for screening?
These are the following criteria:
- parturient age exceeded 30 years;
- survey results during the first trimester have a number of deviations from the norm;
- the first screening showed pathological changes;
- the first child in the family has genetic diseases;
- the presence of chronic or hereditary diseases in the expectant mother, requiring the use of drugs that are undesirable during pregnancy;
- pre-pregnancy miscarriages, fading of the fetus;
- previous abortions;
- a woman has sexually transmitted diseases;
- expectant mother is a carrier of HIV infection;
- family ties between spouses;
- radiation exposure of one of the spouses before conception;
- infectious diseases transmitted by airborne droplets transferred during the first stages of pregnancy, including influenza.
Screening Results
If you are interested in how many weeks screening is done, then you should also know what the results of examinations of a pregnant woman mean. Attention needs to be focused on quantitative indicators.
The interpretation of the biochemical analysis of blood is as follows:
- ACE (fetal protein) - the norm is 15-95 units / ml, underestimated indicators determine the presence of chromosomal abnormalities, overestimated - underdevelopment of the neural tube, spinal cord.
- Estriol (hormone) - the norm is 9.9-18.9 nmol / l, overestimation shows problems with the functioning of the internal organs of the pregnant woman, underestimation - chromosomal abnormalities of the fetus.
- HCG (hormone) - the norm is 4720-80100 IU / l, overestimation indicates chromosomal abnormalities in the development of the fetus, underestimation can mean delays in development, the threat of miscarriages, a frozen pregnancy.
Ultrasound results, no matter how many weeks a second screening is done, can show the following picture:
- placental maturity;
- the state of the genital organs of a woman;
- fetal position;
- place and condition of the umbilical cord;
- IAH - oligohydramnios may be fraught with underdevelopment of the skeleton of the fetus and the nervous system;
- the condition of the internal organs of the fetus, the presence of limbs, the sex of the future baby.
Cordocentesis allows you to make an approximately accurate diagnosis of chromosomal abnormalities and hereditary diseases transmitted from parents to the fetus. The karyotype defined in this way allows you to make a choice between preserving the pregnancy or terminating it.
When can screening be untrue?
Taking into account all of the above, it should be concluded that regardless of how many weeks they do a second screening and ultrasound during pregnancy in particular, the results of the procedures cannot be 100% accurate.
Deceptive indicators can be:
- if the future woman in labor has chronic diseases;
- with a small or excessive body weight of a woman;
- in case of non-compliance with a full nutrition schedule;
- with high nervous tension;
- when carrying several children;
- with too large a fruit;
- at conception using IVF.
How to avoid inaccuracies in indicators?
Closer survey indicators to more accurate and truthful can be subject to the following recommendations:
- to give up smoking;
- dieting for a day and starvation six hours before the donation of blood from a vein;
- restriction of medication one week before the test.
Preparation for cordocentesis involves an additional set of studies.
Now you know how many weeks the second screening is done and for what purpose. The list of examinations for each woman in labor is individual. Their timely passage reduces the risks of bearing a defectively developed child. Remember this!