During pregnancy, the obstetrician-gynecologist necessarily directs pregnancy on ultrasonography (US). And it has done it three times: at the end of each trimester. At each stage, the doctors get their, invaluable important information about the status of the fetus.
There have been many clinical studies showing that ultrasound during pregnancy is perfectly safe. It is solely for the study of fetal development and no harm it causes no.
The first ultrasound: 10-14 weeks
All expectant mothers prescribed ultrasound at the end of the first trimester of pregnancy at time of 10-14 weeks. Already at this point, you can determine whether there are any serious fetal abnormality. In this period the doctor measures the distance from the coccyx to the crown of the embryo (this figure is called CTE), studying the anatomy of the fetus. According to this indicator can be seen as the fruit of a fully developed and whether its size norm.
Uzi during pregnancy: in what period and why
It is also estimated nuchal (TVP). With this indicator, you can see whether the fetus chromosomal abnormalities. If more than 2.7 mm TVP may suspect chromosomal abnormalities. First of all - the probability of Down syndrome in the fetus. If the doctor suspected threat, and still have to pass a blood test to clarify the future health of the baby.
By 12-14 weeks of time to develop almost all the organs of the fetus. Therefore, we can see the most obvious birth defects of the brain, the heart, the presence of unwanted formations. In case of severe pathologies it is not too late to terminate the pregnancy for medical reasons.
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A second US: 20-24 weeks
Boy or girl
In theory, sex of the fetus can be determined starting from the 12th week of pregnancy. However, it is best seen on the 16-20 week. By this time, the fetus genitals significantly increase in size and easier to see. So ask the question of sex determination of the child is during the second ultrasound. However, an absolute guarantee you will not be. Pose the child may simply not to allow the doctor to see his floor.
The second ultrasound doctor measures the abdominal circumference, femur length, interparietal size of the fetal head. On the basis of these indicators can be judged whether the lag in the development of the future baby. In addition, the ultrasound specialist assesses such factors as blood flow in the vessels of the placenta, its location, level of maturity structure. This is very important because premature detachment of the placenta is very dangerous, and may be the reason for hospitalization. A thickening of the placenta is often a sign of infection, diabetes and other diseases that can harm the fetus.
The study of amniotic fluid may provide additional information about the development of the fetal kidney. Polyhydramnios may indicate Rh-conflict or any infection. In both cases, you need special therapy and supervision by a doctor. Exploring the umbilical cord, the doctor looks, whether its entanglement. However, at this stage it is not so important as in the subsequent examination.
A study of cervical clarifies whether cervical incompetence. This pathology, in which the cervix begins to open before 37 weeks, which can lead to preterm labor.
Third US: 32-34 weeks
By this time the fetus is usually time to take a final position inside the uterus and pelvic stay or head end "to the exit." Therefore, an obstetrician-gynecologist will be able to decide in advance how to birth. With the ultrasonic device can determine the approximate weight of the fruit, its size, calculate the approximate delivery date.
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Also, evaluate the position of the placenta, as a 32-34 week it has migration ends. Normally, the placenta is attached at the top of the uterus, away from the neck. But sometimes, for various reasons it is shifted down to the cervix and overlaps it. This so-called placenta previa, which entails a caesarean section - because the placenta is blocking the baby out of the uterus.
Furthermore, the degree of ripeness is evaluated placenta. If it matures early, it is imperative to give birth on time or a little earlier. Perenashivanie in this case leads to the risk of hypoxia in the fetus. During this period, an expert inspects the back for an ultrasound apparatus for the presence of umbilical cord entanglement. It is important for doctors who will accept delivery.