When a woman has a serious delay in critical days, the gynecologist directs the patient to an ultrasound diagnosis to confirm or deny the presence of pregnancy. First of all, the doctor looks at the contents of the uterus, whether there is a fetal egg in it.
Why is having a fetal egg important?
A fetal egg found with an ultrasound in the uterine cavity is the first confirmation of a healthy uterine pregnancy. At the same time, thoroughly studied sizes of the fetal egg by weeks allow us to find out the exact gestational age, as well as to predict the further course of pregnancy.
From the beginning to the middle of the first trimester, the ovum is one of the main indicators of a good development of the embryo. As the size of the fetal egg grows over the weeks of pregnancy, its size and filling may indicate a successful pregnancy, possible problems, and even a missed pregnancy.
How is the presence of a fetal egg determined?
A gynecologist using a chair examination and palpation can only suggest the presence of a fetal egg in the uterus, based on an increase in organ size. Namely, a doctor can see a fetal egg only with the help of an ultrasound machine.
As a rule, transvaginal ultrasound is performed in the early stages, and it gives the most accurate results, since with this diagnostic method the uzist can get as close to the studied object as possible.
Fetal egg - what is it?
A fetal egg is an accumulation of cell mass resulting from the fusion of an egg and sperm and the further division of a fertilized egg.
The shape of the cell mass can be round or oval, but cases of deformation are not excluded. As a rule, diagnosticians look more carefully at unusual forms; more frequent observations of the development of the embryo are not excluded in such situations. But talking about some problems with the unusual shape of the egg is not worth it, as it may be due to the tone caused by the ultrasound machine itself. By removing the device for a while or reducing the pressure, the uzist can see that the shape has changed and normalized.
How does the ovum appear
The cell mass travels for some time through the fallopian tube, heading for the uterus and the site of its future implantation. A week after fertilization, the fetal egg is attached to any wall of the uterus that is convenient for this, using the villi located on the outer shell of the egg, destroying the micro part of the uterine mucosa and vascular walls during implantation. All the time of the journey and the formation of the fetal egg, the cells feed on substances from the egg, after which the nutrients will begin to come from the placenta.
At 3 weeks from conception, the size of the fetal egg increases significantly, since a "baby place", in other words, the placenta, begins to grow from a set of cells embedded in the uterine wall. In it, the fetus will live, eat and develop until the very birth.
Again, the size of the fetal egg will increase at 5 weeks of pregnancy. At this time, the embryo can already be seen inside the egg. It is worth noting that if at this time the uzist did not see the embryo in the fetal egg, then there can be no talk of a frozen pregnancy, since the discrepancy in the timing of growth of the fetal egg is quite large and can reach two weeks.
The thing is that it is impossible to determine the exact gestational age during natural conception due to the fact that ovulation in a woman can take place on different days of the cycle, fertilization can also be delayed, attachment can take place faster or slower. Therefore, the gestational age is set based on the beginning of the last critical days, which is the obstetric period, not embryonic, and if at 5 weeks of gestation the embryo is not visible inside the egg, the ultrasound is repeated again after two weeks. Most often, a repeated ultrasound embryo is already visible.
Weekly Sizes
It is not necessary that the size of the fetal egg for weeks coincides exactly with the standards. Possible error reaches two weeks. In some cases, for example, with late ovulation, the error may be even greater, the fetal egg may have a larger or smaller diameter and this will be the norm, but only if the fetus develops normally.
Here are the sizes of the fetal egg by weeks on an ultrasound scan:
- Until the 5th week of pregnancy, the fetal egg is very small, by the end of the fifth week it reaches 18 millimeters, and the volume is 2187 millimeters per cube, but in the fourth week it has a diameter of only 7 millimeters. If the egg has a small diameter, then this indicates a short time elapsed after conception.
- Already at the 6th week the size reaches 22 millimeters.
- At 7 weeks, the size of the fetal egg is already 24 millimeters.
- In the following weeks, the growth of the fetal egg is spasmodic, in the eighth week of pregnancy it will already be 30 millimeters, in the future the egg will grow weekly on average by 6-8 millimeters.
- By the 13th week, the diameter will already reach 65 millimeters, and the volume will be equal to 131 070 millimeters per cube.
Ovum growth
The size of the fetal egg by week also gives an idea of what size embryo is hiding in the egg. Each week, the embryo develops as rapidly as its house, while the size of the embryo and the egg correspond to:
- At 5 weeks, the coccygeal-parietal size is 3 millimeters.
- At 6 weeks already 6 millimeters.
- At the 7th week, it grows to 10 millimeters.
- At 8 weeks, not only KTR is estimated, but also the biparietal size, namely the estimated width of the embryo's head, KTR at this time is 16 millimeters, and BPR is already 6.
- From 9 to 13 weeks, the embryo grows on average by 10-13 millimeters weekly, and by the end of the first trimester its growth reaches 66 millimeters. The width of the head also grows all this time, at 9 weeks - 8.5 millimeters, at 10 - 11, at 11 - 15 millimeters, at 12 - 20 and at 13 already reaches 24 millimeters.
It is also worth paying attention to the fact that in the weeks between the main screenings, the size of the egg and the parameters of the embryo may not be so perfectly calibrated, therefore, for screening studies, weeks are allocated when the fetus in all its indicators fits the average, in the first trimester, for example This is 11-14 weeks of gestation. Before the first screening, at about 9 weeks of gestation, the uzist and gynecologist check the ratio of the size and the presence of a fetal heartbeat, in accordance with these data, adjustments can be made to the estimated duration of pregnancy.
How many fetal eggs can be
Depending on how many eggs are fertilized at the same time or in a short period of time, one or more fetal eggs appear.
As a rule, if we are talking about twins, that is, about the fertilization of one egg in which two embryos were born, then the fetal egg is one and it is divided into two parts closer to the moment of attachment to the wall of the uterus or not at all. In all other cases, during multiple pregnancy there will be as many fetal eggs as there are fertilized eggs, that is, two or more. In conditions of multiple pregnancy, the size of the fetal egg will differ slightly from the norm by weeks, since the development of the pregnancy itself is a little more complicated, the distribution of nutrients and space in the uterus also goes differently.
Fetal egg and artificial insemination
Of particular note is the fact that with the advent of such techniques for fertilization as IVF, multiple pregnancies, with the development of several multiple fetal vesicles, it has become much larger.
With artificial insemination, everything happens a little differently, since a fertilized fetal egg with the age known to doctors is placed in the uterus, because the size of each fetal egg usually corresponds exactly to the embryonic period and may not correspond to the gestational age.
All ultrasound transcripts regarding the size of the fetal egg and embryo should be recognized directly from the uzist who performed the diagnosis, as well as from a personal gynecologist, since only they will be able to correctly evaluate absolutely all indicators, taking into account the specific features of pregnancy.