Screening for the first trimester of pregnancy – whatneed to know about norms and results

Update: October 201eight

Almost every pregnant woman has heard something about screening.
first trimester of pregnancy (prenatal screening). But often
even those who have already passed it, do not know what exactly is it for

And future moms who still have to come, this phrase
in general, sometimes it seems scary. And it only scares the fact that
the woman does not know how to do it, how to interpret it later
results, why the doctor needs it. On these many other questions,
concerning this topic, you will find the answers in this article.

So, not once had to deal with the fact that a woman
hearing the incomprehensible and unfamiliar word screening, began to draw in
her head, horrible pictures that scared her, causing her
desire to refuse to conduct this procedure. Therefore,
The first thing we will tell you is what the word “screening” means.

Скрининг (англ. screening — сортировка) – это различные
research methods that, because of their simplicity, safety and
accessibility, can be used massively for large groups of individuals, for
identify a number of signs. Prenatal, means prenatal. So
Thus, we can give the following definition of the term “prenatal

Screening for the first trimester of pregnancy is a complex
diagnostic studies used in pregnant women
certain gestational age to detect gross defects
fetal development, and the presence or absence of indirect signs
fetal developmental abnormalities or genetic abnormalities.

Допустимый срок для проведения скрининга 1 триместра – это eleven
weeks – 13 weeks and 6 days (see
weekly pregnancy). No screening earlier or later
as in this case, the results will not be
informative and reliable. The best time
считается eleven-13 акушерских недель of pregnancy.

Who goes to the first trimester screening

According to the order №fourfive7 of the Ministry of Health of the Russian
Federation of 2000, prenatal screening recommended
hold all women. A woman can refuse him, no one
she will not be forced to do this research, but to do so is extremely
recklessly and speaks only of illiteracy and negligent woman
attitude towards yourself and above all to your child.

Risk groups for which prenatal screening should be conducted in
without fail:

  • Women whose age is 3five years or more.
  • Наличие угрозы прерывания early pregnancy.
  • Самопроизвольный(е) выкидыш(и) в anamnesis
  • Замершая(ие) или регрессирующая(ие) беременность(и) в
  • The presence of occupational hazards.
  • Ранее диагностированные хромосомные аномалии и (или)
    fetal malformations by past screening
    pregnancy, or the presence of children born with such
  • Women who have had an infectious disease in the early stages
    of pregnancy.
  • Women taking drugs prohibited by
    приему беременным, на ранних сроках of pregnancy.
  • The presence of alcoholism, drug addiction.
  • Hereditary diseases in the family of a woman or in the family of the father
  • Близкородственная связь между матерью и отцом

Пренатальный скрининг на сроке eleven-13 weeks беременности,
consists of two methods of research – this is an ultrasound screening of the 1st trimester
and biochemical screening.

Ultrasound screening

Preparation for the study: If the ultrasound is transvaginal
(the sensor is inserted into the vagina), then no special preparation is required.
Если УЗИ проводится трансабдоминально (датчик контактирует с
anterior abdominal wall), the study is conducted with complete
bladder. It is recommended for this 3-four hours before
urinate, or for an hour and a half before the study drink five00-600 ml
water without gas.

Necessary conditions for obtaining reliable ultrasound data.
According to the norms, screening of the first trimester in the form of ultrasound

  • Не ранее, чем в eleven акушерских недель и не позже 13 weeks и 6
  • КТР (копчико-теменной размер) плода не меньше fourfive мм.
  • The position of the child should allow the doctor to adequately conduct all
    measurements, otherwise, it is necessary to cough, move,
    walk around for some time for the fruit to change its position.

AT  результате УЗИ исследуются следующие показатели:

  • КТР (копчико-теменной размер) – измеряется от теменной
    bone to the tailbone
  • Head circumference
  • BPR (biparietal size) – distance between parietal
  • The distance from the frontal bone to the occipital bone
  • The symmetry of the hemispheres of the brain and its structure
  • ТATП (толщина воротникового пространства)
  • Fetal heart rate (heart rate)
  • The length of the humerus, femur, and forearm bones and
  • The location of the heart and stomach in the fetus
  • The size of the heart and large vessels
  • The location of the placenta and its thickness
  • Amount of water
  • The number of vessels in the umbilical cord
  • The state of the internal throat of the cervix
  • The presence or absence of hypertonicity of the uterus

Decryption of the data:

KTR, mm ТATП, мм Nasal bone, mm Heart rate beats per minute BPR, mm
ten недель 33-four1 1.five-2.2 ATидна, размер не оценивается 161-179 1four
eleven недель four2-five0 1.6-2.four ATидна, размер не оценивается 1five3-177 17
12 weeks five1-five9 1.6-2.five More than 3 mm 1five0-17four 20
13 weeks 62-73 1.7-2.7 More than 3 mm 1four7-171 26

What pathologies can be detected as a result of ultrasound?

According to the results of the first trimester ultrasound screening, we can talk about
the absence or presence of the following anomalies:

  • Down syndrome – трисомия по 21 хромосоме, самое
    common genetic disease. Распространенность
    identify 1: 700 cases. Thanks to prenatal screening
    рождаемость детей с синдромом Дауна снизилась до 1:1ten0
  • Pathology of the development of the neural tube (meningocele,
    менингомиелоцеле, энцефалоцеле и другие).
  • Omphalocele – a pathology in which part of the internal organs
    located under the skin of the anterior abdominal wall in the hernial sac.
  • Patau syndrome – trisomy 13 chromosome. Frequency of occurrence
    в среднем 1:ten000 cases. 9five% of babies born with this syndrome
    die within a few months due to severe damage
    internal organs. On ultrasound – rapid heartbeat of the fetus,
    impaired brain development, omphalocele, slower development
    tubular bones.
  • Edwards syndrome – трисомия по 1eight хромосоме. Frequency
    встречаемости 1:7000 cases. More common in children whose mothers
    over 3five years old. On ultrasound, a decrease in fetal heart rate is observed,
    omphalocele, nasal bones not visible, one umbilical artery instead
  • Triploidy – a genetic abnormality in which there is
    triple set of chromosomes, instead of double set. Accompanied by
    multiple fetal malformations.
  • Cornelia de Lange syndrome – генетическая аномалия, при которой
    the fetus has various malformations and, in the future,
    mental retardation. Frequency of occurrence 1:ten000 cases.
  • Синдром Смита-Опица – аутосомно-рецессивное генетическое
    a disease manifested by a violation of metabolism. AT результате
    what the child has multiple pathologies, mental
    retardation, autism and other symptoms. Frequency of occurrence в
    среднем 1:30000 cases.

More information about the diagnosis of Down syndrome

Главным образом, ультразвуковое исследование на сроке eleven-13
weeks of pregnancy is carried out to detect Down syndrome.
The main indicator for diagnosis is:

  • Толщина воротникового пространства (ТATП). ТATП – это расстояние
    between the soft tissues of the neck and the skin. Increase collar thickness
    spaces can talk not only about increasing the risk of birth
    a child with Down syndrome, but that others are possible
    genetic abnormalities in the fetus.
  • У детей с синдромом Дауна чаще всего на сроке eleven-1four недель не
    visualized nasal bone. The contours of the face smoothed.

До eleven недель беременности толщина воротникового пространства
so small that it is impossible to adequately and reliably evaluate it.
After 1four weeks, the lymphatic system forms in the fetus and this
the space can normally be filled with lymph, so the measurement
also not reliable. Frequency of occurrence хромосомных
abnormalities in the fetus, depending on the thickness of the collar

ТATП, мм Frequency аномалий, %

Увеличенная ТATП

Нормальная ТATП

3 7
four 27
five five3
6 four9
7 eight3
eight 70
9 7eight

При расшифровке данных скрининга 1 триместра  следует
remember that only one indicator of collar thickness
spaces is not a guide to action and does not talk about
ten0% вероятности наличия заболевания у baby

Therefore, the next stage of the 1st trimester screening is carried out – taking
blood to determine the level of β-hCG and PAPP-A. Based on the received
indicators, calculated the risk of the presence of chromosomal pathology.
If the risk from the results of these studies is high, then suggest
hold amniocentesis. This is taking the amniotic fluid to
more accurate diagnosis.

AT особо трудных случаях может потребоваться кордоцентез – взятие
cord blood for analysis. Can also use villus biopsy
chorion. ATсе эти методы являются инвазивными и сопряжены с рисками
for mother and fetus. Therefore, the decision to hold them is decided
a woman and her doctor together, taking into account all the risks of
rejection of the procedure.

Biochemical screening for the first trimester of pregnancy

This phase of the study is carried out after ultrasound. it
important condition because all biochemical indicators depend on
gestation right up to the day. Every day norm indicators
are changing. And ultrasound allows you to determine the duration of pregnancy with
accuracy that is necessary for proper
research. At the time of donating blood, you should already have
the results of ultrasound with a specified period of pregnancy on the basis of KTR. Also
on ultrasound may be detected missed abortion, regressing
pregnancy, in this case, further examination does not have

Preparation for the study

ATзятие крови проводится натощак! It is not advisable to even drink water
this morning. If the study is too late,
allowed to drink some water. It is better to bring food and
to have a snack right after blood sampling, rather than disturbing it

2 days before The designated study day should be excluded from
ration all foods that are strong allergens, even
if you have never had allergies on them – these are chocolate, nuts,
seafood, as well as very fatty dishes and smoked meats.

Otherwise, the risk of false results is significantly

Рассмотрим, о чем могут свидетельствовать отклонения от
normal indicators of β-hCG and PAPP-A.

β-hCG – chorionic gonadotropin

This hormone is produced by the chorion (the “shell” of the fetus),
thanks to this hormone it is possible to determine the presence
early pregnancy. The level of β-hCG is gradually increasing.
in the first months of pregnancy, its maximum level is observed
at eleven-12 weeks of pregnancy. Then the level of β-hCG gradually
decreases, remaining unchanged throughout the second half
of pregnancy.

Normal levels of human chorionic gonadotropin, in
depending on the duration of pregnancy:
Increased β-hCG levels are observed in the following cases: The decrease in the level of β-hCG is observed in the following cases:
Weeks β-hCG, ng / ml
  • Down syndrome
  • Multiple pregnancy
  • Severe toxicosis
  • Diabetes in the mother
  • Edwards syndrome
  • Ectopic pregnancy (but it is usually established
    even before biochemical research)
  • Placental insufficiency
  • High risk of abortion
ten 2five.eight0-1eight1.60
eleven 17.four-130,3
12 13.four-12eight.five
13 1four,2-elevenfour,eight

PAPP-A – pregnancy-associated protein-A

It is a protein produced by the placenta in the pregnant woman’s body.
women, is responsible for the immune response during pregnancy, and
responsible for the normal development and functioning of the placenta.

Normal indicators of the level of PAPP-A, depending on the period
Deviations indicator
Weeks PAPP-A, honey / ml «-»   При снижении его уровня увеличивается риск следующих

  • Cornelia de Lange syndrome
  • Down syndrome
  • Edwards syndrome
  • The threat of premature abortion

«+»  Изолированное повышение уровня этого белка не имеет
clinical and diagnostic value.

ten-eleven 0.fourfive – 3.73
eleven-12 0.7eight – four.77
12-13 1.03 – 6.02
13-1four 1.four7 – eight.fivefive

MoM coefficient

After receiving the results, the doctor evaluates them, expecting
MoM coefficient. This ratio shows the level deviation.
indicators for this woman from the average normal value. AT
MoM-rate is 0.five-2.five (for multiple fetuses
pregnancy up to 3.five).

Factor and indicator data may vary in different
laboratories, hormone levels and protein can be calculated and in
other units. Do not use the data in the article
как нормы именно к ATашему исследованию. Results needed
treat along with your doctor!

Further, using the computer program PRISCA, taking into account all
indicators, the age of the woman, her bad habits
(smoking), the presence of diabetes and other diseases, weight
women, the number of fruits or the presence of IVF – calculated risk
birth of a child with genetic abnormalities. ATысокий риск – это
risk less than 1: 3eight0.

Пример: Если в заключении указано высокий риск
1: 2eight0, which means that out of 2eight0 pregnant women with the same
indicators, one child will be born with a genetic

Especially situations when indicators can be other.

  • IVF – β-hCG values ​​will be higher, and PAPP-A – below average.
  • With obesity in women, hormone levels may increase.
  • With multiple pregnancies, β-hCG is higher and the norm for such
    cases not yet established exactly.
  • Diabetes in the mother может вызвать повышение уровня

Автор: Ревус Олеся Григорьевна врач-невролог

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