fetal health

Fetal echocardiography

Generality

Fetal echocardiography is an exam that allows you to study the anatomy and heart function of the child when it is still in the womb. This survey is performed in the second trimester of pregnancy, in order to identify malformations and congenital diseases affecting the heart and large vessels .

Echocardiography is not part of normal routine checks, but is indicated by the gynecologist when particular fetal or maternal risks are present (ie suspected of congenital heart disease at the first level exam or previous or current pregnancy diseases).

The main indications for the execution of the exam are:

  • Fetal heart disease found on morphological ultrasound;
  • Maternal disorders (diabetes, phenylketonuria, autoimmune diseases or infections acquired during pregnancy);
  • Previous child or family member with congenital heart disease;
  • Exposure to teratogenic substances and / or drugs (anticonvulsants, alcohol, lithium etc.);
  • Chromosomal abnormalities and extra-cardiac fetal malformations;
  • Nuchal translucency increased in the first trimester;
  • Monochorionic twin pregnancy.

Fetal echocardiography can be performed from the 16th week, but the best results, in terms of quality, are obtained after 20-22 weeks of gestation.

The examination is not dangerous or painful: fetal echocardiography allows the evaluation of the child's heart through the maternal belly, using sound waves with a technique similar to that of a normal ultrasound. Unlike the latter, however, fetal echocardiography requires a longer time to study all cardiovascular components in depth (30-35 minutes).

The diagnosis of heart disease in the fetal era is very important, since, from the moment of birth, the child can be assisted with the most suitable medical or surgical therapies.

What's this

Fetal echocardiography consists of a detailed examination of the anatomy and cardiac function in the prenatal period.

The purpose of this investigation is to highlight or exclude the presence of pathologies of the heart and large vessels . Fetal echocardiography is indicated by the gynecologist in cases in which malformations in the development of the fetus are suspected which can compromise the correct functioning of the heart muscle.

Remember : fetal echocardiography allows the early diagnosis of most congenital heart defects before birth.

Fetal echocardiography is a diagnostic technique that is performed transabdominally, that is by placing a specific probe on the abdomen, after having sprinkled it with gel to improve the diffusion of ultrasound (high-frequency sound waves, falling within the band not audible by the ear human).

Why do you run it?

Fetal echocardiography allows screening and early diagnosis of congenital heart disease in the fetus. The examination is not part of the normal routine checks, but is required by the doctor when there are situations of suspicion or predisposition to the development of cardiac abnormalities against the child. The risk is represented, for example, by family predisposition to congenital heart disease, infections contracted by the mother during pregnancy (such as rubella), diabetes and autoimmune diseases.

The recognition of malformations and heart diseases when the fetus is still in the uterus is very important. At the end of the gestation, in fact, the birth can be planned, with the most suitable methods and times, in structures able to assist the cardiopathic newborn. In this way, from the moment of birth, it is possible to promptly establish the medical or surgical treatment appropriate to the case.

Note

In the general population, the probability of conceiving a fetus with a cardiac malformation is about 1%. However, there are some situations where this risk increases. Among the birth defects, cardiopathies with onset in the fetal era represent the main cause of infant mortality.

Fetal indications

Fetal echocardiography is required when particular fetal cardiac risks are present, such as:

  • Suspicion of congenital heart disease on morphological ultrasound;
  • Alteration of persistent fetal heart beat (arrhythmias);
  • Early onset growth retardation (second trimester);
  • Monochorionic twinning;
  • Abnormal fetal karyotype highlighted with amniocentesis or villocentesis;
  • Extra-cardiac malformations;
  • Fetal hydrops (increased fluids in fetal tissues) non-immunological;
  • Detection of nuchal translucency increased in the first trimester, with normal karyotype (NT greater than the 99th percentile, ie over 3.5 mm).

Maternal indications

The indication to be examined can also be based on maternal risk factors:

  • Familiarity with congenital heart disease (existence of previous births or full-blown cardiac malformation in one of the two parents);
  • Hereditary diseases and genetic syndromes associated with congenital heart disease;
  • Infections contracted during pregnancy (toxoplasmosis, rubella, cytomegalovirus, parvovirus B19, coxsackie etc.);
  • Metabolic disease prior to pregnancy (insulin-dependent diabetes, phenylketonuria, etc.);
  • Autoimmune disorders (eg systemic lupus erythematosus and anti-phospholipid antibody syndrome);
  • Taking medications or exposure to teratogenic agents (including alcohol, retinoids, phenytoin, trimetadione, carbamazepine, lithium carbonate, valproic acid and paroxetine).

Fetal echocardiography can be performed until the end of pregnancy to monitor the evolution of cardiac and / or fetal arrhythmias.

When do you run?

In general, fetal echocardiography is performed after morphological ultrasonography, when it is necessary to check the anatomy of the child's heart muscle and detect the presence of a congenital heart disease.

In cases where maternal or fetal indications are precocious, the examination can be performed starting from the 16th week of gestation, even if a certain and reliable diagnosis is not guaranteed, for the level of development and for the conformation of the fetus. To have a greater diagnostic accuracy (equal to about 90%), it is advisable to wait until the 20th-22nd week of pregnancy. Once the 20 weeks of gestation have come, however, the analysis can be performed at any time if there is a need.

In the presence of complex congenital heart disease, the doctor may indicate to repeat the exam once a month and to anticipate the birth in case of signs of fetal heart failure .

How to do it

Fetal echocardiography is performed by a transabdominal approach : the echocardiographic probe is placed on the mother's abdomen and an initial two-dimensional anatomical evaluation of the child 's heart is performed, followed by a functional study .

How ultrasound works

The ultrasound examination allows exploring the internal organs of the body, using ultrasounds, produced by the vibration of piezoelectric crystals contained in the probes. The wall of the uterus, the amniotic fluid and the fetal tissues reflect part of these waves generating a series of reflected echoes. The latter are recorded by the ultrasound probe and are decoded by the central unit of the instrumental apparatus, which transforms the information acquired into images visible on a monitor.

During the examination, the doctor can acquire some standard projections useful for identifying the anatomical structures of the fetal heart: cardiac chambers, atrioventricular and ventricular-arterial connections, systemic and pulmonary venous returns, etc. On the same echocardiographic scans, functional assessment is performed by color doppler or with the help of the pulsed doppler. With this method we observe the circulation inside the heart and in the large vessels, in addition to the arteriovenous flow in the umbilical cord.

The integration of the information obtained with fetal echocardiography allows to better study the connections between the various cardiac structures, their morphological characteristics and their function.

Who does it run from?

The examination is performed by specialized operators, who during their professional training have acquired specific experience on the pathophysiology of various fetal malformations and on their ultrasound identification. In the interpretation of the findings, however, the gynecologist and the pediatric cardiologist must be involved.

In the event of congenital heart disease, a diagnostic in-depth examination and an adequate informational interview with the future mother are indicated.

The best gestational period to perform fetal echocardiography is between the 20th and 22nd week, but it is possible to start the study of the heart of the fetus early, especially in high-risk cases.

How long does it last?

The duration of the examination is variable: as a rule, for the acquisition of the ultrasound images in different projections it takes at least 30-35 minutes, as it is necessary to study in detail all the components of the heart of the fetus in depth.

What does the report contain?

In the report of fetal echocardiography, the anatomical description (normal or pathological) and the diagnostic conclusion are reported, with the eventual iconographic documentation attached.

Preparation

Fetal echocardiography does not foresee any particular norm of preparation by the expectant mother. The patient is usually recommended to bring along the documentation relating to the previous exams for the comparative evaluation of the reports.

To perform the fetal echocardiogram, the pregnant woman is laid on the echocardiographic table in a supine position. The echocardiographic probe is placed, then, on the abdomen in specific points, based on the position of the fetus in utero, in order to better study the heart.

No preparation is required for this type of exam.

Accuracy

Fetal echocardiography identifies about 80-90% of congenital heart disease .

Certain variables relating to the examination technique contribute decisively to the final value of the general diagnostic accuracy, including:

  • Thickness of the maternal adipose panniculus;
  • Amount of amniotic fluid;
  • Position of the fetus.

Also, keep in mind that:

  • Some defects of the interventricular septum (especially muscle) are barely visible to ultrasounds, due to the resolution limit of the instrumental apparatuses;
  • The fetal circulation in the uterus is physiologically different from the post-natal one; this makes it impossible to diagnose some conditions (such as that of patent ductus arteriosus) and that of inter-atrial defect is difficult.
  • In some cases, the defect is evolutionary, ie the picture worsens over time and may become evident only in the third quarter; for this reason, some malformations are visible only in the third trimester (as happens in the case, for example, of stenosis of semilunar valves and aortic coarctation).

In some cases, it may happen that the in utero diagnosis of some abnormalities is not confirmed at birth : for example, a small interventricular defect present early in pregnancy can resolve spontaneously during fetal life.

Contraindications

Fetal echocardiography is not normally a painful or dangerous exam for the future mother and does not produce harmful effects on the fetus, even in the long term.

Risks of the method

Fetal echocardiography is a safe method for both the mother and the fetus, as it has been proven that ultrasound does not cause significant biological effects on human tissues and on the evolving organs of the fetus. For this reason, the survey is considered risk-free.

Limits of fetal echocardiography

Some factors may limit the diagnostic capacity of fetal echocardiography.

These include:

  • Overweight or obesity;
  • Abnormalities of amniotic fluid in defect (oligohydramnios) or in excess (polydramnios);
  • Inadequate gestational age (too early or late);
  • Excessive movements or position of the unfavorable fetus;
  • Multiple gestation.

In utero diagnosis and postnatal prognosis

The identification of a malformation in utero is important, especially for the most serious pathologies, since it allows to establish in advance the timing and location of the birth, in a structure able to provide adequate assistance to the newborn.