Who should use fetal echocardiography?
Congenital heart defects are the most common group of developmental defects and one of the main causes of neonatal mortality. Moreover, many of them can be successfully corrected if the diagnosis is known in advance: the birth is planned in an institution with a cardiac surgery service, and the newborn receives care in the first hours of life, and not after the development of a critical condition.
Standard screening in the second trimester includes a four-chamber section of the heart and examination of the outflow tracts, but this is not enough if there is an increased risk. Targeted fetal echocardiography is indicated for congenital heart defects in parents or previous children, diabetes mellitus and systemic connective tissue diseases in the mother, taking teratogenic drugs, early infections, increased thickness of the nuchal translucency in the first trimester, identified extracardiac defects and chromosomal abnormalities, as well as fetal heart rhythm disturbances and non-immune hydrops.
The optimal period is 18–22 weeks, when the heart is already large enough for a detailed examination, and there is enough amniotic fluid for good visualization. If a defect is detected, a pediatric cardiologist is consulted and the delivery route is determined.
Why are planned studies needed?
Ultrasound is the main tool for monitoring pregnancy. It confirms that the fetus is alive and developing on time, shows the number of fetuses, the position of the placenta, the volume of amniotic fluid and the condition of the cervix. Most serious malformations are detected by ultrasound, and at a time when it is still possible to make an informed decision.
There are usually three planned examinations during pregnancy - one in each trimester, in strictly defined windows. Outside of these periods, some measurements lose diagnostic value: for example, the thickness of the collar space can be correctly assessed only from the 11th to the 13th week plus 6 days.
Safety of ultrasound during pregnancy
Ultrasound is not ionizing radiation: it does not accumulate in tissues and does not have a radiation dose, unlike X-rays and computed tomography. Over decades of use, no data have been obtained on the harmful effects of diagnostic ultrasound on fetal development.
In this case, the principle of reasonable sufficiency applies: the study is performed according to indications and in the optimal time frame, and the power and exposure time are kept at the minimum required level. This applies separately to the Doppler and 3D/4D modes - they are used consciously, and not “just in case” at each visit.
What affects image quality
The clarity of the picture depends on the age, position of the fetus, the thickness of the anterior abdominal wall, the amount of amniotic fluid and the presence of a scar on the uterus. If the fetus turns its back to the sensor or covers its face with its hands, some structures cannot be examined.
In such cases, the doctor may ask you to walk, change your body position, or come back in a few days. This is not a sign of pathology, but a common technical situation, especially common during 3D/4D examination.