Ultrasound signs of fetal pathology

Fetal pathology

Anomalies of fetal development

Anomalies of neural tube development

• Anencephaly.
• Hydrocephalus.
• Microcephaly.
• Encephalocele.

Anomalies of the spine

• Myelomeningocele.
• Splitting of the spine (spina bifida).

Cystic hygroma.

Heart anomalies

• Anomalies of the position of the heart.
• Defect of interventricular septum.
• Hypoplasia.

Anomalies in the development of the gastrointestinal tract

• Atresia of the duodenum.
• Atresia of jejunum.
• Cardiac atresia.

Anomalies of anterior abdominal wall development

• Ophalocele.
• Gastroschism.
• Fetal ascites.

Kidney anomalies

• Hypoplasia.
• Obstruction.
• Polycystic kidney disease.

Anomalies in the amount of amniotic fluid

• Malodode.
• Polyhydramnios.

Fetal death

Anomalies of neural tube development

Anencephaly - congenital absence of the cranial vault of the brain - is the most common anomaly in the development of the central nervous system of the fetus. This anomaly is recognized at the 12th week of pregnancy: hydramnion and other anomalies will also be detected. In the amniotic fluid and serum of maternal blood, an elevated level of alpha-fetoprotein will be detected.

Hydrocephalus can be recognized at the 18th week of pregnancy. The expansion of the anterior and posterior horns of the lateral ventricles will be determined.

Hydrocephalus against the background of the Arnold-Chiari syndrome is combined with the lumbar meningocele. The increase in the frontal tubercles gives the head a characteristic shape, in the detection of which a thorough examination of the head and spine is necessary, especially if there is an increase in a-fetoprotein in the mother's blood serum.

If hydrocephalus is secondary to the background of brain atrophy, the fetal head is usually reduced in size.

Microcephaly. A pathological decrease in the size of the head takes place if the biparietal diameter is less than the established average values by more than three standard deviations. It is necessary to determine the biparietal diameter of the fetal head, but it is also necessary to calculate the ratio of the size of the head and body to exclude the intrauterine growth retardation of the fetus. Isolated microcephaly is rare, and diagnosis in borderline cases is always complicated. Serial studies and a very cautious interpretation are necessary. Except for cases with a sharp decrease in the head of the fetus, try not to diagnose microcephaly, unless there are other abnormalities of development.

Be very careful with the diagnosis of microcephaly. Serial research is necessary.

Encephalomeningocele. This defect in the development of the neural tube is usually defined as a round protrusion in the region of the bones of the cranial vault containing fluid or medulla. The most common occipital encephalomeningocele, but in some ethnic groups there is an anterior encephalocele. In the presence of asymmetric encephalocele, amniotic constrictions will also be determined. The most common cause of the error is a similar shadow caused by the ear of the fetus or limb located next to the head. Repeat the test in different planes and at another time. Errors can also occur in the presence of a cystic hygroma, but the bones of the cranial vault will be intact. Encephalocele can be combined with polycystic kidney disease or polydactyly.

Recognizing neurological abnormalities can be extremely difficult. It is always necessary to confirm their presence in repeated studies and, preferably, also by another specialist.

Anomalies in the development of the spine

Anomalies in the development of the spine most often affect the cervical and lumbar spine. It is necessary to investigate soft tissues above the spine to determine continuity of their contour, and also the spine for the presence of additional formations. The spine of the fetus can distinctly differentiate starting from the 15th week of pregnancy.

Myelomeningocele is visualized as a liquid-containing saccular formation located behind, often having elements of the spinal cord in the cavity. Open myelomeningocele may not have a superficial "sac" - it will only determine the prolapse of soft tissues through a defect: the myelomeningocele without the bulging of the contour is particularly difficult to detect. Bone anomalies are usually determined. Normally, posterior centers of ossification are visualized as two hyperechoic linear, almost parallel echostructures, however, when they split the spine (spina bifida), their discrepancy will be observed. On normal transverse sections, the centers of ossification from the rear look parallel; in the presence of spina bifida, the posterior elements are laterally displaced, not parallel, diverge outwards. Longitudinal sections are used to identify the hernial sac.

Not all stages of spina bifida can be detected by ultrasound.

Cystic hygroma

Cystic hygroma is an anomaly of the development of the lymphatic system, with a cystic formation with septa located in the cervical region posterior. This formation can spread laterally and anteriorly; in some cases, septa or structures resembling the spokes of the wheel are identified in the center. Unlike encephalocele or cervical meningocele, the skull and spinal cord are intact.

When the cystic hygroma is combined with a generalized abnormality of the lymphatic system, fluid is detected in the abdominal cavity, in the pleural cavities, and the survival of the fetus is unlikely.

Anomalies of fetal heart development

The detection of most heart anomalies requires special equipment, with the possibility of carrying out Doppler study, as well as special knowledge. Anomalies of the position of the heart, hypoplasia of one half, defects of the interventricular septum can be detected, however in any case, if an anomaly of the heart is suspected, an additional expert opinion is needed. If the final diagnosis is difficult to establish, clinicians should be warned about possible complications, so that they are ready to provide specialized assistance in the birth of a child.

Anomalies of development of the intestine of the fetus

Congenital bowel obstructions most often occur either in the duodenum, or in the jejunum or ileum.

1. Atresia of the duodenum is the most common anomaly in the development of the gastrointestinal tract. In this case, the rounded cystic structures in the upper part of the abdomen of the fetus will be visualized. The cystic structure on the left is the dilated stomach, the cystic structure on the right is the duodenum. This is the echographic sign of the "double bubble". In 50% of cases, this anomaly is combined with polyhydramnios in Down's syndrome, and often anomalies of the heart, kidneys, central nervous system.
2. Atresia of the jejunum and ileum. Diagnosis can be complicated. In the upper part of the abdomen of the fetus, multiple cystic structures can be visualized; it is overgrown loops of the intestine. Usually, this anomaly is revealed in the second usual ultrasound study in the III trimester of pregnancy. Polyhydramnios usually occur in the presence of high intestinal obstruction, localization of obstruction in the lower divisions of polyhydramnios is not observed. Combined anomalies are much less common than with duodenal atresia.
3. Obstruction or atresia of the colon. This developmental defect is rare, and it is almost impossible to make an accurate diagnosis from ultrasound data.

Anomalies in the anterior wall of the fetal abdomen

The most frequent developmental abnormality is the defect of the anterior abdominal wall along the midline (omphalocele); Ophalocele is often combined with other congenital anomalies. Depending on the size of the defect, the hernial sac may contain part of the intestine, liver, stomach and spleen, covered externally by the amniotic membrane, and from the inside - by the parietal peritoneum. The umbilical cord usually penetrates into the hernial sac and spreads inside the wall of the hernial sac.

Other defects are mainly defined in the right podopump region (gastroschisis) and are usually isolated. Through this defect, only loops of the intestine that are not covered by the amniotic membrane usually prolapse. When echography is determined loops of the intestine, floating in the amniotic fluid outside the front abdominal wall. The umbilical cord enters the abdominal wall normally.

Ascites from the fetus

Free fluid in the abdominal cavity of the fetus is defined as an anechoic zone surrounding the internal organs of the fetus. In the presence of true ascites, the fluid surrounds the crescent ligament and the umbilical vein. It is mistaken for ascites to be taken hypoechoic rim around the abdomen, due to the presence of muscle and fatty layers of the abdominal wall.

If suspicion of ascites is necessary, the anatomy of the fetus must be carefully studied to exclude the associated anomalies. The most common causes of ascites are renal obstruction or dropsy. Since ascitic fluid can be represented by urine, it is necessary to carefully examine the kidneys. The dropsy can not be diagnosed until there is a thickening of the skin or presence of fluid in at least two cavities (eg, ascites along with pleural or pericardial effusion). The most common causes of dropsy are:

• Rhesus-conflict or incompatibility of other blood factors;
• heart abnormalities;
• arrhythmias of the heart (usually tachyarrhythmia);
• vascular or lymphatic obstruction (for example, with cystic gigroma).

Anomalies in the development of the fetal urinary system

Some abnormalities of kidney development are incompatible with life, and if detected within a period of up to 22 weeks, indications for abortion (where permitted) can be determined. Recognizing anomalies later in pregnancy can also affect the management of a pregnant woman.

The presence of echographically unchanged (in size, shape, echogenicity) kidney does not exclude the possibility of an abnormality in the development of the urinary system.

Syndrome of kidney agenesis (missing kidneys). There is no amniotic fluid and ultrasound diagnosis is difficult. In the last few weeks of pregnancy, a false impression of the presence of the kidneys can be created due to a significant increase in the adrenal glands, which acquire the bean-like form of the kidneys. The bladder is usually small or nonexistent. It is necessary to cut in different planes.

Hypoplasia of the kidneys (small kidneys). Measuring the kidneys will show their decrease.

Kidney obstruction; hydronephrosis. It should be borne in mind that the transient expansion of the renal pelvis is permissible. Such dilatations are more often bilateral, but they can be one-sided and persist for some time. Repeat the test after 2 weeks. If the dilatation of the renal pelvis is physiological, the diameter of the renal pelvis either remains the same, or the dilatation disappears.

With a pathological dilatation, negative dynamics will be observed. Bilateral renal obstruction (bilateral hydronephrosis) is usually combined with malnutrition and has an unfavorable prognosis. Unilateral obstruction is not combined with anhydrous, as the opposite kidney takes on the function of both kidneys.

In some cases, there is polyhydramnios. With echography in the central part of the kidneys there is a cystic formation with smaller in diameter cystic structures located outside. These smaller cysts (up to 1 cm) in the projection of the parenchyma of the hydroschemically altered kidney may be a sign of infrequent dysplasia of the kidney. Increased echogenicity and reduced thickness of the parenchyma are fairly accurate signs of impaired renal function.

In the presence of obstruction at the level of the ureteropelvic segment, the renal pelvis has a rounded shape, and the ureter is not visualized. If there is obstruction of the internal opening of the urethra (usually with the urethral valve in male fetuses), there is a bladder dilatation, as well as an expansion of both ureters and renal pelvis. Sometimes stretching of the posterior urethra in the form of a bulging of the urethra contour can be determined.

Multicystic kidney. With echography, several cysts of different diameters will be detected, usually located diffusely, less often in one part of the kidney. Two-sided vice is incompatible with life. The tissue of the kidney can be determined between the cysts, although the parenchyma does not clearly differentiate, since the tissue will be much more echogenic than the normal parenchyma of the kidney.

Autosomal recessive polycystic kidney is usually recognized only in the III trimester of pregnancy. Usually there is a hereditary anamnesis and low blood pressure due to a sharp decrease in kidney function. Both kidneys can be so enlarged that they can be taken for the liver, but the shape of the kidneys persists. Individual cysts are not visible, since their diameter is too small to be differentiated, but the presence of a multitude of reflective surfaces gives a sharp increase in the echogenicity of the kidneys.

Amniotic fluid

Increase in the amount of amniotic fluid (polyhydramnios, hydramnion). An increase in amniotic fluid can occur with various fetal pathologies. The most common causes of polyhydramnios are:

• Gastrointestinal obstruction (high obstruction of the jejunum or higher);
• anomalies of the central nervous system and neural tube defects:
• dropsy of the fetus;
• slight defects in the anterior abdominal wall;
• Skeletal dysplasia of the chest (microsomia) - defects, usually incompatible with life;
• multiple pregnancies;
• diabetes in the mother.

Decrease in the amount of amniotic fluid (hypochlorism).

In general, the production of amniotic fluid of the fetus, starting from 18-20 weeks of pregnancy, is due to renal secretion. In the presence of bilateral renal obstruction, renal dysplasia or dysfunctional kidneys, the amount of amniotic fluid is sharply reduced or absent. This can lead to pulmonary hypoplasia.

Malnutrition develops due to:

• damage to shells with leaking fluid;
• bilateral renal abnormality or anomaly of the development of the urinary tract (abnormalities of the kidneys, ureters or urethra);
• intrauterine growth retardation;
• masturbation of pregnancy;
• intrauterine fetal death.

Most formations in the abdominal cavity of the fetus are of kidney origin.

Multicystosis can be one-sided and two-sided, with unrelated cysts being identified.

Autosomal recessive (infantile type) polycystic is echographically defined as "large white kidneys": individual brushes do not differentiate.

Malnutrition is a poor prognostic sign in the presence of kidney anomalies, as this leads to hypoplasia of the lungs.

Intrauterine fetal death

The diagnosis is established in the absence of fetal heartbeat. A normal fetus may be characterized by a transient bradycardia or a syncopal absence of the heartbeat, so monitoring is necessary for several minutes. Other signs of fetal death are low blood pressure, as well as damage to the bones of the skull with the appearance of bone fragments one by one (Spalding's sign).