With the help of ultrasound from relatively recent time, future moms can not only see a clear volumetric and color image of their crumbs on the screen of the monitor (3D ultrasound), but also trace its facial expressions and movements in real time (4D ultrasound). Of course, the function of ultrasound, as a safe method of diagnosis, is much broader than simply familiarizing the mother with the baby before delivery. In midwifery, it is necessary to determine ectopic pregnancy, assess the condition of the fetus, identify its developmental defects, monitor the implementation of invasive procedures (amniocentesis, chorionic biopsy, cordocentesis) and fetometry, which determines the size of the fetus by ultrasound.
Passing mandatory ultrasound screenings - the key to successful pregnancy
In order to diagnose the normal development of pregnancy, the lack of threat of its interruption and possible deviations from the norm, pregnant women should undergo ultrasound screening 3-4 times during the gestation period. For example, the ultrasound of the fetus for a period of 10-12 weeks is aimed at determining the number of fetuses, identifying such serious malformations as Down's syndrome, Edwards on the basis of the study of markers of these chromosomal pathologies: the thickness of the collar space (informative for fetal growth by ultrasound 45-83mm ) and the length of the bones of the nose. For the purpose of reliability of the received data, in addition to ultrasound, a "biochemical" screening can also be prescribed. Within the first mandatory ultrasound, the fetal limbs, the structure of its brain, the heart, the stomach, the bladder, the spine and the child's movements are determined.
The ultrasound of the fetus at 20-24 weeks assesses the condition of the placenta, the amniotic fluid in it, is performed to eliminate fetal malformations, including in the heart, and more accurately determine the sex of the child. At 30-32 weeks, the ultrasound of the fetus is necessary to determine its approximate weight, the state of the umbilical cord, to measure the size of the child's head with the mother's birth canal.
Determination of the exact period of birth - the task of fetometry
At each session, the exact term of delivery is necessarily determined, but the most informative is if it is established in the first trimester of pregnancy. During this period, the fetal sizes determined by ultrasound in pregnancy, such as KTP (coccyx-parietal size) and DPR (diameter of the fetal egg) are usually standard, later they can be influenced by various factors. So, simultaneously with these indicators, the definition of the period of pregnancy and childbirth occurs by evaluating and comparing other fetometric indicators with the norms of fetal size by ultrasound.
The main components of fetometry are:
- BDP (biparietal size, which is the size between the temporal bones). On the study, it may happen that the fetal head is fixed in the entrance to the small pelvis. In this case, it is usually not possible to determine the BDP, in connection with which, the ultrasound protocol will have the item "it is impossible to determine the BDP". All attempts to measure it can lead to errors in diagnosis, and as a result of the incorrect tactics of conducting labor. It may also be that the dimensions of the head will be increased transversely (brachycephaly) or longitudinally (dolichocephaly). Such phenomena, along with the usual ellipsoidal shape, the heads are variants of the norm, but can lead to mistakes in determining the gestational age and fetal weight by ultrasound. To establish the correct diagnosis, attention should be paid to the study of other indicators of fetometry);
- LZR (frontal-occipital size);
- OG (head circumference);
- OJ (abdominal circumference) is one of the main diagnostic criteria for intrauterine growth retardation (FGP), as it helps to determine fetal weight by ultrasound;
- DLB (thigh length). This indicator should be used for the purpose of determining the duration of pregnancy only if it is impossible to obtain BDP or with a non-standard form of the head, while it is the most important factor in detecting skeletal dysplasia;
- DGRK (diameter of the chest), etc.
Scientifically proven that the simultaneous use of several indicators makes it much more accurate to determine the duration of pregnancy. At a period of up to 36 weeks, it is best to study the population of BDP, DLB and OZH, after the same - OZ, OG and DLB.
As a rule, the conclusion is made on the basis of the ultrasound table of the fetal dimensions of ultrasound, an example of which is presented below:
Due to the fact that each unit can be configured for different tables with fetal sizes for weeks, the ultrasound protocols may have significant differences.
If the size is less than the pregnancy period indicated in the table, and if a small weight of the fetus has been determined by ultrasound, the diagnosis of the HPV is usually made. For its confirmation, additional ultrasound is performed in dynamics, cardiotocography and dopplerography are prescribed. In any case, if the parameters do not match, you should not panic at once, because the reason can be banal - the pregnancy period is incorrectly set due to inaccuracy in determining the date of ovulation. Often this situation is typical during lactational amenorrhea.