An ultrasound examination in the third trimester of pregnancy is performed for certain medical reasons. Usually, such a study is assigned to a pregnant woman, whose fetus has certain developmental pathologies.
Purpose of the
The study performed during this period of pregnancy quite often coincides with the time of the third screening. Usually, this examination is performed at 30-32 weeks of intrauterine fetal development.
It should be noted that an ultrasound scan at this stage of pregnancy may not be shown to all women.
With an ultrasound scan, doctors can determine main indicators of fetal development... This method allows for a complete complex fetometry. This study includes quite a few different parameters.
32 obstetric week is the period when the baby's body is almost completely formed. This physiological feature makes it possible to determine quite a few different indicators.
Quite often, doctors prescribe an ultrasound scan to determine the final tactics of obstetrics... Mothers who have a breech presentation of the fetus at this time may also need to repeat the ultrasound examination a couple of weeks before delivery.
Ultrasound at 31-32 weeks of pregnancy can also be prescribed with multiple pregnancies. This situation is especially common in the event that one of the fetuses has defects in intrauterine development. In difficult clinical cases, doctors may resort to the appointment of an expert-level ultrasound examination.
Of course, during the ultrasound examination, you can also determine the sex of the unborn baby. This is usually done when a pregnant woman has missed a prior screening. In most cases, the sex of the unborn child is determined in the middle of the second trimester.
Ultrasound at this stage of pregnancy can be done in different ways. Doppler ultrasonography is used to determine blood flow pathologies. Using this method, diagnosticians can identify various pathologies of the placental and uterine blood vessels feeding the fetus.
Doppler sonography is also successfully used to identify developing heart defects in the fetus.
It should be noted that future mothers who, during the ultrasound scan at this stage of pregnancy, doctors found any deviations from the norm, should not immediately start to panic.
One conclusion of the ultrasound test is not yet a diagnosis at all. The interpretation of the result is necessarily carried out by an obstetrician-gynecologist who observes a pregnant woman throughout the entire period of pregnancy.
Main investigated parameters
The third trimester is the final stage of the intrauterine development of the baby. To assess pathologies during this period of pregnancy, doctors have developed a number of different clinical indicators.
For a comprehensive conclusion, a comparison of all the results obtained is required.
Fetometry - baseline research that is actively carried out during this period. This method allows you to assess the main indicators of the anatomy of the fetus. For this, during the study, the ultrasound doctor evaluates several parameters. These indicators include biparietal size and circumference of the fetal head, as well as abdominal circumference.
Necessarily determined the dimensions of the main tubular bones. For this, their length is estimated. Too short long bones can be a sign of some genetic diseases or developing pathologies of the musculoskeletal system.
During the study, which is carried out at this stage of pregnancy, the abdominal circumference. Doctors have found that this rate is often related to head circumference. If the baby's tummy is too large in diameter, then this can be a manifestation of a very dangerous pathology - ascites. It is characterized by the accumulation of excess fluid in the child's abdominal cavity.
At this stage of pregnancy, you can determine and estimated weight of the baby. An experienced ultrasound specialist will determine how much the fetus weighs with an accuracy of tens of grams. A fetus that is too large is usually an indication for a caesarean section, especially if the mother's pelvis is too narrow. Being underweight usually affects one or both babies with multiple pregnancies.
Assessment of the work of all vital systems of the fetus Is a very important step in ultrasound examination. At this time, the doctor already perfectly determines the fetal heartbeat. An excess or decrease of this indicator below normal values indicates the formation of pathologies in the work of the cardiovascular system. Such manifestations are especially dangerous if the mother has a history of heart disease.
Identifying heart defects is essential. Modern techniques make it possible to detect such defects quite effectively. Pathologies of the development of heart valves and the appearance of pathological blood flows (regurgitation) on them may become an indication for surgical correction immediately after the birth of a child.
With the help of ultrasound at this stage of pregnancy, it is also possible to identify various abnormalities in the development of the kidneys and urinary tract in the fetus. Qualified specialists can also determine the emerging pathologies of the pelvis and bladder. Along with the study of the urinary system, the doctor necessarily assesses the work of the gastrointestinal tract and the respiratory system in the fetus.
A baby's spine is examined only if there is a suspicion of genetic or chromosomal diseases. For this, the ultrasound doctor examines a linear section of the spine. The spinous processes are also being studied. If, during the study, an ultrasound specialist has identified any significant defects and he has suspicions about the presence of signs of chromosomal diseases, then he will send the expectant mother to a geneticist for a consultation.
The placenta, or "baby seat", is a very important organ during pregnancy. Through it, the baby receives all the necessary nutrients, as well as oxygen. This is due to the same uteroplacental blood flow system with the mother.
Assessment of the thickness of the placenta, as well as the tone and structure of its blood vessels, is necessarily carried out during the study during this period of pregnancy.
During any ultrasound examination, the doctor necessarily evaluates and the main parameters of the internal genital organs of the expectant mother... This is necessary for the timely detection of pathologies that can lead to disruption of the course of pregnancy and difficulties during childbirth.
For this, the inner surface of the uterus is examined, and the size of its appendages and ovaries is also determined. During ultrasound, neoplasms and cysts can be detected. If these pathologies in a pregnant woman were identified even before pregnancy, then in such a situation the dynamics of their growth is necessarily assessed. In case of an unfavorable course of fibroids or cysts, a careful selection of the necessary tactics of obstetrics may be required.
Norms of the studied parameters
Doctors consider cephalic presentation normal. Too active babies can change their position in the womb several times. Usually, by the end of the third trimester, presentation has already become permanent. In some situations, doctors may prescribe and repeat an ultrasound scan in 2-3 weeks.
The location of the placenta on the back wall is the most optimal. Also, doctors determine how high this organ is located from the internal os of the uterus. If the placenta attaches to it too low, then this may be a consequence of its accretion or lead to various pathologies.
During the research, it is also necessary the cervix is evaluated. Normally, this figure should be more than 30 mm. The shortening of the cervix is an extremely unfavorable symptom of ischemic-cervical insufficiency. In this case, additional suturing is required in order to eliminate this pathology.
It is very important during such a study to evaluate and uterine tone. Hypertonia can lead to premature birth. Also, this condition contributes to the formation of placental insufficiency.
The amniotic fluid index is a very important indicator, which is also assessed during this period of pregnancy. Too much of its accumulation is a manifestation of polyhydramnios. Normally, this figure is 140-269 mm. A significant decrease in this indicator indicates the manifestation of low water.
Fruit size
For the convenience of assessing the intrauterine development of the fetus at this stage of pregnancy, doctors use a special table, which presents all normal values of the main investigated indicators:
Decoding the results
Future mothers should remember that the interpretation of the obtained research values is carried out by an obstetrician-gynecologist, and not an ultrasound specialist. One conclusion of an ultrasound test is not yet a diagnosis. To confirm or exclude pathology in the fetus, it is also required to compare the ultrasound conclusion with biochemical analyzes that were carried out at different periods of pregnancy.
Tachycardia - an unfavorable symptom that may indicate fetal hypoxia. The development of this condition can lead to the entanglement of the baby's neck with the umbilical cord. Also, palpitations are common with some heart defects.
Bradycardia detected at this time in the fetus may be the result of a delay in intrauterine development. This symptom also manifests itself in the presence of some cardiovascular anomalies. A decrease in the fetal heart rate below 130 beats per minute requires a thorough diagnosis. to identify various defects of the valvular apparatus of the heart.
At this stage of pregnancy, maturity of the placenta is usually first degree. At earlier stages, it is zero. With the course of pregnancy, the maturity of the placenta increases. If the placenta does not "mature" for childbirth, then this is already a pathological condition.
A study of the thickness of the placenta is also required. A smaller thickness of this organ is found with the possible development of placental insufficiency. Too thick placenta may indicate the development of edema or inflammation. Various viral and bacterial infections lead to the development of such pathological changes.
