Ultrasound during pregnancy

Ultrasonic diagnosis in obstetrics has been in use for about 30 years. Although it is believed that ultrasound is almost harmless, nevertheless, studies are still being conducted to confirm this situation. Echography is the most important tool for examining pregnant women and can be used for clinical indications at any time of pregnancy.

Is a normally occurring pregnancy indicative of ultrasound examination?

This issue is still being discussed, and research is being carried out. Nevertheless, during physiological pregnancy, there are two periods, when the echography is most useful and gives the greatest amount of information.

These periods are:

1. From 18 to 22 weeks of pregnancy from the first day of the last menstruation.
2. From 32 to 36 weeks of pregnancy from the first day of the last menstruation.

The most informative time period for the first study (weeks)

1	2	3	4	5	6th	7th	8
9	10	Eleven	12	13	14	15	16
17th	18	19	20	21	22	23	24

The most informative time period for the second study (weeks)

25	26th	27th	28	29	Thirty	31
32	33	34	35	36	37	38
39	40

Why is ultrasound performed in a physiologically occurring pregnancy?

Many doctors believe that the echography is not needed for a normal pregnancy. Other doctors recommend a study, since many fetal malformations can not be detected in a clinical study.

1. 90% of fetal malformations occur without having a similar history in the family history, and only a very small number of mothers have obvious risk factors.
2. There may be very significant malformations of the fetus even in clinically safe pregnancy.
3. Neither a clinical examination nor a family history is a clear enough way to establish a multiple pregnancy.
4. A significant number of pregnant women with low-lying placenta (placenta previa) have no clinical signs of this pathology until they begin to bleed during physical exertion. The situation can become quite critical, especially if the patient is away from the hospital.
5. Up to 50% of women who claim that they know the exact length of pregnancy, in fact, make mistakes more than 2 weeks when compared with the data of the echography. The period of 2 weeks is extremely critical for the survival of the fetus in the presence of indications for early delivery in connection with antenatal complications.

When is the ultrasound seen before 18 weeks of pregnancy?

The patient should undergo a thorough clinical examination with a positive pregnancy test or no menstruation. Ultrasound scanning can help if there are clinical data on a possible pregnancy pathology or if there are doubts about the timing of pregnancy.

Why is an ultrasound done in the early stages of pregnancy (up to 18 weeks)?

Ultrasound in early pregnancy is carried out:

1. To confirm the presence of pregnancy.
2. For an accurate determination of the gestation period.
3. To clarify the location of the fetal egg (in the uterine cavity or ectopic).
4. To identify multiple pregnancies.
5. For the exclusion of a bubble drift.
6. To exclude false pregnancy in the presence of formations in the small pelvis or hormone-active tumors of the ovaries.
7. For the diagnosis of fibroids or ovarian formations that could interfere with the normal course of labor.

Umbilical cord and umbilical cord

The umbilical cord is already determined in the first trimester of pregnancy in the form of a cord from the basal plate of the chorion to the embryo. Longitudinal and transverse sections allow one to visualize one umbilical vein and two umbilical arteries. If only two vessels are visualized, this always means that there is no second artery, which is always accompanied by a high risk of intrauterine fetal death and fetal abnormalities that occur in 20% of cases.

There is also a high risk of intrauterine growth retardation in the presence of only one artery of the umbilical cord. It is necessary to record the growth rates of the fetus for each study.

Multiple pregnancy

It is important to determine the position of each fetus and the amount of placenta in detecting multiple pregnancies. You can visualize the interamnotic septum, which is usually easily identified in the first and second trimesters of pregnancy. If the fruits are raznoyaytsovye, then this means the presence of dizygotic twins. It is necessary to measure each fetus to reveal the pathology of development of each of them. It is also necessary to take into account the amount of amniotic fluid in each fetal egg.

The conclusion: an echography during pregnancy

Many doctors believe that there is no need for a routine ultrasound study at any stage of physiological pregnancy and that ultrasound is performed only in case of suspicion of the presence of a pathology that occurs during a clinical study. Other doctors believe that it is necessary to conduct two standard studies for better antenatal diagnosis.

[1], [2], [3], [4], [5], [6]

Indication and timing of additional ultrasound studies

Ultrasound can not explain the minor or moderate intensity of abdominal pain, except for signs of pre-eclampsia.

Indications for additional ultrasound studies are:

1. Intrauterine growth retardation.
2. Low location of the placenta: repeat the study at the 38-39th week of pregnancy and, if necessary, immediately before childbirth.
3. Fetal pathology; repeat the study at week 36.
4. Inconsistency of the size of the uterus and the timing of pregnancy: repeat the study at the 36th week of pregnancy or earlier, if the discrepancy is sufficiently pronounced.
5. Known or suspected fetal pathology: repeat the study at 38-39 weeks.
6. Unexpected bleeding.
7. Absence of fetal movements or other signs of intrauterine fetal death: repeat the test immediately, and in case of doubt - after another 1 week.

Preparing for ultrasound examination during pregnancy

1. Preparation of the patient. The bladder should be filled. Give the patient 4 or 5 glasses of fluid and conduct the test an hour after this (the patient should not urinate). If necessary, fill the bladder through the urethral catheter with a sterile saline solution: the bladder filling stops when there is a feeling of discomfort in the patient. If possible, avoid catheterization due to the risk of infection.
2. Position of the patient. The patient is usually examined in a relaxed state lying on his back. If necessary, you can turn the patient in the process of research. Apply the gel arbitrarily to the lower abdomen: there is usually no need to apply the gel to the pubic hair, if necessary, apply the gel to this section.
3. Select the sensor. Use a 3.5 MHz sensor. Use a 5 MHz sensor for thin women.
4. Adjust the sensitivity level of the device. Place the transducer longitudinally on the projection of the filled bladder and set the sensitivity level necessary to obtain the optimal image.

What is important in the study from 18 to 22 weeks of pregnancy?

This is the optimal period for:

1. Establishment of exact terms of pregnancy.
2. Diagnosis of multiple pregnancies.
3. Diagnosis of fetal pathology.
4. Definitions of the location of the placenta and the detection of placenta previa.
5. Identification of fibroids or other pelvic formations that may interfere with the course of pregnancy or childbirth.

What is important in the study from 32 to 36 weeks of pregnancy?

This is the optimal period for:

1. Diagnosis of fetal development retardation syndrome.
2. Exposure of the pathology of the fetus, which was not detected at the first. Ultrasound study.
3. Prescribing placenta previa and determining the position of the fetus.
4. Definitions of the exact location of the placenta.
5. Determination of the number of amniotic fluid.
6. Exceptions of concomitant pathology, eg fibroids, ovarian tumors.

18-22 ned pregnancy

Echography on these terms of pregnancy will help to answer the following questions:

1. Is there a singleton or multiple pregnancy?
2. Does the actual duration of pregnancy correspond to what is expected from a clinical trial?
3. Do fetal development parameters correspond to normal parameters for a given gestation period?
4. Is the anatomy of the fetus normal?
5. Is fetal activity normal?
6. Is the condition of the uterus normal?
7. Is the amount of amniotic fluid normal?
8. How is the placenta?

32-36 ned pregnancy

Echography on these terms of pregnancy will help to answer the following questions:

1. Are fetal development rates normal?
2. Is the condition of the fetus normal? Are there abnormalities of development?
3. What is the position of the fetus (although it may change before delivery)?
4. How is the placenta?
5. Is the amount of amniotic fluid normal?
6. Are there associated diseases, for example, fibroids, ovarian tumors that can affect the course of pregnancy and childbirth?

[7], [8], [9], [10], [11]

Late gestation

If the patient has not previously undergone ultrasound, when studying in late pregnancy, echography will help answer the following questions:

1. Is there a singleton or multiple pregnancy?
2. Does the degree of maturity of the fetus correspond to the established term of pregnancy?
3. What is the position of the fetus?
4. What is the location of the placenta? In particular, it is necessary to exclude the presence of placenta previa.
5. Is the amount of amniotic fluid normal?
6. Are there abnormalities of fetal development?
7. Are there associated diseases, for example, fibroids, ovarian tumors that can affect the course of pregnancy and childbirth?

[12], [13], [14], [15], [16], [17], [18], [19]

Ultrasound examination before and after fetal head removal procedure

It is often necessary to conduct a study directly before turning the fetus from the pelvic to the head position to be sure that the fetus has not changed its position.

After the procedure, an ultrasound examination is necessary in order to ensure that the fetal position has become normal.

Ultrasound in early pregnancy (up to 18 weeks)

If ultrasound is shown, it is preferable to wait until 18-22 weeks of pregnancy, as the information obtained during the study at these times will be most accurate. However, there may be indications for performing ultrasound at earlier times, for example:

1. Vaginal bleeding.
2. The patient does not know the date of the last menstruation or there are other reasons to suspect the timing mismatch.
3. Absence of signs of the fetal life when a pregnancy is suspected.
4. Presence in the anamnesis of pathology of previous pregnancy or childbirth or other obstetric or genetic diseases.
5. The presence of an intrauterine contraceptive.
6. Presence of indications for abortion.
7. The patient is especially worried about the well-being of this pregnancy.

Ultrasound in the middle of pregnancy (28-32 weeks)

It is desirable to postpone studies to 32-36 weeks of gestation, but there may be clinical indications for ultrasound at an earlier time, for example:

1. Clinical problems with the position or size of the fetal head.
2. Clinical research allows you to suspect pathology.
3. In previous ultrasound studies, some pathology was noted or they were unsatisfactory in quality.
4. The position of the placenta was not accurately determined or the placenta was located close to the internal uterine throat during a previous ultrasound study.
5. The uterus is too large for the established term of pregnancy.
6. There is a leakage of amniotic fluid.
7. There is pain or bleeding.
8. Unsatisfactory state of the mother.

Ultrasound during labor

Indications for ultrasound during labor are:

1. Unstable state of the fetus.
2. Impossibility of clinical registration of palpitation of the fetus.
3. Inconsistency of gestational age and fetal size.
4. Unusually violent bleeding.
5. Weakness of labor or other complications of the birth act.

Ultrasound in the postpartum period

There are usually no clinical indications for routine ultrasound in the postpartum period, but there may be some clinical situations in which ultrasound can provide useful information.

In the early postpartum period:

1. Uterine bleeding.
2. Incomplete separation of the placenta or delay in the uterus of the placental tissue.
3. The protracted period of the expulsion of the second fetus from twins.

After 6 weeks after delivery:

1. Continuous bleeding.
2. Constant pain.
3. Subinvolution of the uterus in the postpartum period.
4. Continuing vaginal discharge.
5. Palpable formations in the pelvis.

When is echography not recommended?

The ultrasound is not recommended in the first trimester of pregnancy, if there are no clinical indications.

What is being studied in a normal pregnancy?

Many doctors believe that the possible risk and high cost of ultrasound studies of all successively women with a normal pregnancy is not justified in terms of benefits for patients.

The question of whether or not to conduct a study with a normal pregnancy is decided each time individually by the patient or by the doctor. In this issue there are no uniform rules and recommendations.

Determination of the sex of the fetus is not an indication for ultrasound examination, except for cases with a history of sex-related hereditary disease.

Is ultrasound safe during pregnancy?

Yes, as far as is known. Nevertheless, it is necessary to perform ultrasound examination only on clinical indications.

Why is echography not recommended at the first visit to a pregnant doctor?

Some doctors recommend that an ultrasound be performed at the first visit to a doctor by a pregnant woman, but this is not necessary in cases where there are no clinical indications. If there are indications, then the study is preferably performed at the time from 18 to 22 weeks of pregnancy, when the echography provides the most important information.

There is no need to conduct an ultrasound scan every month or every visit to a pregnant doctor, unless there are reasons for clinicians to suspect a pathology requiring dynamic observation.