First screening: ultrasound and blood chemistry
Pregnancy screening is a complex of studies. It includes ultrasound diagnostics (ultrasound) and a biochemical blood test. The first screening allows doctors to get detailed information about the health of the fetus and the expectant mother. The doctor makes all the indicators in a special program. It automatically calculates whether there are opportunities for the development of pathologies and the risks of anomalies. With its help, various developmental anomalies are eliminated, and the physiology of the unborn baby is revealed.
First trimester screening
A study is being conducted between the eleventh and thirteenth weeks of pregnancy. There is no point in conducting it earlier. Most of the data will be non-indicative.
The first screening includes two medical tests – ultrasound and hormone analysis.
Thanks to this study, the doctor can determine the duration of pregnancy. It is also possible to check fetal rate indicators. The sizes of the child, the correct functioning of the heart, brain are estimated. Amniotic fluid volume, placenta quality are measured. The condition of the uterus, its tone are investigated. The doctor compares each indicator with the standards of the norm. At the first screening, they are:
CRL The length of the fetus from the coccyx to the crown is measured.
It should be in the range of 43 to sixty-five millimeters. Sometimes the indicator may be higher. This means that the fetus may be larger than usual. But an understated figure may indicate a delay in development. Most often, this is due to the hormonal failure of the mother, or her infectious diseases. Genetic pathologies are also possible, and even the death of the baby (when the heartbeat is not heard).
BDP (biparietal head size).
The distance from the temple to the temple is measured. Allowed size from 17 mm to 24 mm. Exceeding the indicator may again indicate a large fruit. But if all other studies are normal. In others, a suspicion of a brain pathology may arise. Underestimated indicators of biparietal size indicate its slow development.
TVP. Sizes range from 1.6 mm to 1.7.
The thickness of the collar space is an indicator that is responsible for severe genetic diseases such as Down syndrome. However, based only on TBP indicators, such a serious diagnosis is never made. If there is a suspicion of chromosomal abnormalities, an additional blood test and a biopsy of the outer shell of the fetus are done.
The length of the nose bone.
Normally, it should be from 2 to 4.2 mm. Understated indicators can speak of a serious pathology, as well as of an ordinary snub nose. In this case, the values of other measurements are taken into account again.
Heart rate (heart rate)
The heart of the embryo at this time should beat from 140 to 160 beats per minute. Deviation of up to forty strokes in both directions is allowed.
The size of the chorion (the shell of the embryo, which in the future will turn into a placenta).
It is very important where it is located. If this is the lower wall of the uterus, there is a risk of miscarriage. Expectant mother is shown bed rest.
The size of the amion.
It is a shell in which amniotic fluid is located. At the first screening, their volume should not exceed one hundred ml.
The size of the yolk sac.
This organ of the embryo replaces some of its internal organs. By 11 or 13 weeks it should not be visualized. If the doctor is able to determine the size of the yolk sac, this may indicate pathologies.
The length should be between 35 and 40 mm. If the indicator is significantly underestimated, then there may be a risk of miscarriage or premature delivery.
Methods of ultrasound and preparation for the procedure
There are two ways that an ultrasound can be performed:
In the first case, the device’s sensor is located on the stomach of the future mother. In the second – in the vagina. Most often, they prefer the transvaginal method, since it is more informative and accurate.
Before the diagnosis should be prepared. If there is a transabdominal ultrasound method, then you should drink about a half liter of liquid. The bladder will fill and displace the uterus so that it is easy to see.
Before transvaginal ultrasound, on the contrary, you should visit the restroom so as not to experience discomfort during the study. You also need to wash yourself with soap or take a shower.
In Russia and other post-Soviet countries, a blood test is not included in standard screening. Doctors prescribe only an ultrasound. Blood sampling is carried out either at will, or in case of suspected pathology of the fetal development.
Blood biochemistry is often called a double test. This is due to the fact that it is carried out to indicate the level of 2 hormones:
PAPP-A. At this stage of embryo development, the hormone content standard is between 0.79 and 6.01 units. An underestimated rate may be a harbinger of the hardest genetic chromosomal diseases, fetal fading, hypotrophy and preeclampsia.