In what period an ultrasound detects pregnancy?


Correctly set the duration of pregnancy by ultrasound is an important concern of almost all moms. When to go for an ultrasound, when to give birth, when to go to register – all that interests a woman. Ultrasonic diagnostics is the most informative method of research in determining the early periods of gestation. In addition, ultrasound can determine the approximate date of birth, find out whether the fetus is supplied with oxygen and the condition of the placenta. The method has the high precision – accuracy is 3-4 days.

Ways to determine pregnancy

In obstetrics there are several ways to determine pregnancy. These include:

Any woman is important as early as possible to find out whether the place of conception or not, to know the exact date of birth. The question of when to go to ultrasound is very important. In any case, after unprotected PA, even if it was ovulation, it should take more than 10-14 days — so much the fertilized egg descends into the uterus and attaches to the endometrium. Only after this ultrasound you can see the fertilized ovum. As for HCG, a value of more than 1-2 thousand mu/l it is possible to go inspect the embryo on ultrasound.

How to find out the duration of pregnancy by ultrasound?

The minimum period of gestation when it is possible to confirm the pregnancy – obstetric 3-4 weeks when using a transvaginal transducer. Early ultrasound doesn’t show the embryo, the doctor may measure the internal size of the ovum. At this time ultrasonography is not recommended without strong evidence, for example, suspected ectopic or missed abortion.

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5-6 obstetric weeks it becomes possible to see the embryo during transabdominal ultrasound. At this period the benchmark is the distance from the fetal skull to the coccyx in mm – kopchik-parietal size, or CTE. There are average values that are appropriate for the age of gestation, they range from 5 to 92 mm, values of more talk about possible deviations in development.

In the 2nd and 3rd trimester the fetus is well seen, and the specialist can differentiate the parts of his body. For setting the exact age of the fetus in this pregnancy is determined fotometricheskie settings. These include:

  • The circumference of the fetal head (HC).
  • Biparietal head size (BPR) – the distance between the upper and lower contour of the parietal bone.
  • Fronto-occipital head size (LZR) – the distance measured between the outer contours of the occipital and frontal bones.
  • Abdominal circumference (RC).
  • Length of the femur (DBK).
  • The length of the Shin bone (DKG).
  • Length of the humerus (WPC).
  • Length bones of the forearm (DCT).

The measurement heads is carried out at transverse scanning of the embryo, the sections carried out at the height of the optic tubercles of the brain. The doctor not only measures but also evaluates the structure of the brain, cranial bones, their integrity.The size of the fetus increase proportionately with the increase of the period, and in the second trimester, the growth parameters more pronounced than the third. 3 trimester obstetric to determine the age of the embryo is much more complicated due to the large scatter of the values of the measured parameters. Measurement of HCG level at this period is impractical – until the birth, its value in the third trimester will fall.All measured parameters will be displayed in the report issued by the woman’s hands, which should go to the gynecologist who is monitoring the pregnancy.

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When to go for ultrasound?

The question is, in what period an ultrasound detect pregnancy and when to go to the research asks every pregnant woman. Do not rush out and conduct a survey immediately after a delay in the early stages – the study is likely to be an uninformative and the embryo is still not visible. Optimal time for ultrasound diagnosis is 20-25 days after delay of menstruation. It is at this period an ultrasound shows the fetal heartbeat, the doctor may assume the date of birth. HCG in this period equal to an average of 100000-200000.

What are the errors in the formulation of the term on an ultrasound?

Like any other method, ultrasound can be wrong or not show pregnancy. It depends on several factors:

  • If a woman is improperly determined the period of delay and came to study too early, even when you cannot see the ovum.
  • Insufficient qualification of the doctor or an old ultrasound machine – not all scanners are able to see the formation in the womb no larger than 3-5 mm. Therefore, it is recommended to diagnose in specialized perinatal centers — in most cases, they are equipped with sensitive devices.
  • Transabdominal shows the pregnancy a week later transvaginal.

Obstetric and fetal periods

There are two concepts that are often confusing and embarrassing a pregnant woman’s obstetric and fetal age of the embryo. Most often, these two terms differ in average by 2 weeks. This is because the embryonic period is the estimated day of ovulation or conception, akushersky put a period on the first day of the last menstrual period – on average 2 weeks more. The expected date of the birth, the obstetrician can expect from midwifery time – 40 weeks, or using the formula on the first day of the last menstrual period minus three months, plus seven days. Received date is approximate, it is possible to prevent deviation in two weeks in both directions. In the conclusion of specified obstetric gestational age.

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Correct gestational age helps the doctor calculate your due date and find out whether the fruit of their obstetric age. But we must not forget that ultrasound, like all other methods of examination may err, and date of birth does not match with the one calculated by a doctor.