1. Diagnostic Medical Sonography Program
Obstetrical Sonography Part I
Lecture 13
Ultrasound evaluation of the Fetal Thorax
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2. The Fetal Thorax

3. Outline Key points for chapter 13
Ultrasound evaluation of the fetal thorax
Congenital cystic adenomatoid malformation (CCAM)
Pulmonary sequestration
Congenital diaphragmatic hernia (CHD)
Pulmonary hypoplasia
Pleural effusion/Fetal hydrothorax
Sonographic Evaluation of Fetal Lung Maturity
Infant Respiratory Distress Syndrome (IRDS)
L/S ratio
Pulmonary Surfactant Lipids
Vernix
Homework

4. Pulmonary Anomalies
Congenital cystic Adenomatoid Malformation of the lung (CCAM)
Cystic Adenomatoid malformation is typically a unilateral condition characterized by the replacement of normal lung parenchyma with abnormal tissue, which often includes visible cysts. In cases where the lesions are large enough, the mediastinum may be shifted away from midline. Three classes of CCAM exist based on the size of the cysts:

5. TYPE I-large cysts 2cm or greater
TYPE II-multiple small cysts < 1-2 cm in diameter
TYPE III-tiny cysts not resolvable sonographically

6. Sonographic findings:
Demonstration of a non-pulsatile echogenic (with solid and cystic components) mass in the fetal lung
Lateral displacement of the heart
Possible sonographic signs of Hydrops Fetalis (most commonly with type III CCAM)
Associated Polyhydramnios

7. Important to recognize the following:
An image of CCAM type I
An image of CCAM type II (showing mediastinal shift)
An image of CCAM Type III

8. CCAM type I

9. CCAM type II (showing mediastinal shift)

10. CCAM Type III

11. Definitions:
Hydrops fetalis: Hydrops fetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments.
Immune Hydrops:
Rh disease is a cause for immune hydrops fetalis; however, owing to preventative methods developed in the 1970s Rh disease has markedly declined.
Non-Hydrops fetalis:
The non-immune form of hydrops fetalis has many causes including:
Iron deficiency anemia.

12. Hydrops Fetalis

13. Pulmonary Sequestration
The separation of a mass of pulmonary parenchyma from the normal lung results in pulmonary sequestration.
This mass receives its blood supply from the systemic circulation and does not communicate with the bronchial tree. Non-Immune Hydrops may be present.

14. Sonographic findings:
Homogeneous echogenic intra-thoracic mass

15. Pulmonary Sequestration

17. Congenital Diaphragmatic Hernia

19. Congenital Diaphragmatic Hernia

20. CDH
Congenital Diaphragmatic Hernia (CDH) is a condition in which a hole in the diaphragm allows abdominal organs to move into the chest and restrict lung development. Congenital diaphragmatic hernia (CDH) is a birth defect that occurs in about one in every 2,500 live births.

21. It is characterized by the development, very early in gestation, of a hole in the diaphragm, the breathing muscle that separates the chest from the abdomen. The hole occurs most commonly on the left side.
As a result, the intestines and other organs in the abdomen can move into the chest and compress the developing lungs. This prevents the lungs from growing and developing normally, which can cause reduced blood flow to the lungs and pulmonary hypertension (high blood pressure in the pulmonary circulation).

22. As with other birth defects, most congenital diaphragmatic hernias (CDHs) are typically discovered by routine ultrasound at 16 to 18 weeks gestation.
It can be life-threatening unless treated.

23. The severity of congenital diaphragmatic hernia (CDH) is largely determined by the position of the liver and the L. Outcomes are generally better in cases where the liver remains down in the abdomen and the lung-to-head circumference ratio (LHR) is higher. The overall survival rate is 70 percent.
Most babies do not survive because of pulmonary Hypoplasia.

24. CDH

25. CDH on MRI

26. CDH on radiography

27. Pulmonary Hypoplasia

28. Pulmonary Hypoplasia

29. Pulmonary hypoplasia is a condition in which the lungs are abnormally small, and do not have enough tissue and blood flow to allow the baby to breathe on his or her own. Sometimes this problem can be fatal.
Most often the pulmonary hypoplasia is a secondary problem due to another diagnosis. Either something is compressing the lungs or preventing the lungs from developing properly.

30. In babies with congenital diaphragmatic hernia (CDH) of the lungs are compressed by the abnormal position of the intestines in the chest.
A baby with massive pleural effusions (fluid buildup around the lungs) can also have very small, underdeveloped lungs.
In babies with bladder outlet obstruction or severe oligohydramnios, there is very little amniotic fluid. The amniotic fluid puts pressure on the lungs to grow and without the pressure, pulmonary hypoplasia develops.

31. Pleural Effusion

33. Fetal Pleural effusion/Fetal hydrothorax
Fetal pleural effusions (also known as fetal hydrothorax) are abnormal accumulations of fluid in the chest cavity. The fluid exists between the lungs and the chest wall and can be on the left, right or both sides. As the fluid increases, it can compress the other structures in the chest such as the lungs and heart. Severe pleural effusions can result in poor development of the lungs or heart failure. Causes of the pleural effusion may include infection, heart conditions, genetic or chromosome problems, abnormal lymph drainage or lung problems but in most cases are unknown.

34. Treatment
Depending on the severity of the effusion and impairment of lung development, the newborn may have difficulty breathing.
Most cases of pleural effusion are mild and children will grow up with normal lung function.
Unfortunately, it is difficult to predict the severity of the lung damage based on prenatal ultrasounds or even shortly after birth.

35. Sonographic Evaluation of Fetal Lung Maturity
What are the indicators for the assessment of fetal lung maturity?
List and describe the amniotic fluid tests of fetal lung maturity.
Describe the relationship between Placental Grade III and fetal lung maturity.
Describe the tissue characterization of the fetal lung.

36. Infant respiratory distress syndrome (IRDS), also called "Respiratory distress syndrome of newborn", previously called hyaline membrane disease), is a syndrome caused in premature infants by developmental insufficiency of production and structural immaturity in the lungs. It can also result from a genetic problem with the production of associated proteins. RDS affects about 1% of newborn infants and is the leading cause of death in preterm infants. The incidence decreases with advancing gestational age, from about 50% in babies born at weeks, to about 25% at weeks. The syndrome is more frequent in infants of diabetic mothers and in the second born of premature twins.

37. Respiratory distress syndrome begins shortly after birth and is manifest by tachypena, tachycardia, chest wall retractions , expiratory grunting, flaring of the nostrils and cyanosis during breathing efforts.
As the disease progresses, the baby may develop rising carbon dioxide concentrations in the blood, and prolonged cessations of breathing ("apnea"). Despite huge advances in care, RDS remains the most common single cause of death in the first month of life. Complications include metabolic disorders (acidosis, low blood sugar), patent ductus arteriosus, low blood pressure, chronic lung changes, and intracranial hemorrhage. The disease is frequently complicated by prematurity and its additional defects in other organ function.

38. Pathology
The characteristic pathology seen in babies who die from RDS was the source of the name "hyaline membrane disease". These waxy-appearing layers line the collapsed tiny air sacs ("alveoli") of the lung. In addition, the lungs show bleeding, over-distention of airways and damage to the lining cells.

39. Pathophysiology
The lungs are developmentally deficient in a material called surfactant, which allows the alveoli to remain open throughout the normal cycle of inhalation and exhalation. Blood oxygen levels fall and carbon dioxide rises, resulting in rising blood acid levels and hypoxia. Structural immaturity, as manifest by low numbers of alveoli, also contributes to the disease process. Therapeutic oxygen and positive-pressure ventilation, while potentially life-saving, can also damage the lung. The diagnosis is made by the clinical picture and the chest xray,

40. Prevention
Most cases of hyaline membrane disease can be prevented if mothers who are about to deliver prematurely can be given one of a group of hormones glucocorticoids. This speeds the production of surfactant. For very premature deliveries, a gluco-corticoid is given without testing the fetal lung maturity. In pregnancies of greater than 30 weeks, the fetal lung maturity may be tested by sampling the amount of surfactant in the amniotic fluid, obtained by inserting a needle through the mother's abdomen and uterus. The 'maturity level' is expressed as the lecithin-sphingomyelin (or "L/S") ratio. If this ratio is less than 2:1 , the fetal lungs may be surfactant deficient, and a glucocorticoid is given.

41. L/S ratio Lecithin-sphingomyelin (L/S) ratio - amniotic fluid
Specimen: Amniotic Fluid
Reference interval: L/S ratio > 2.0 indicates fetal lung maturity
Application: Assessment of fetal lung maturity
Interpretation:
L/S ratio <2.0 indicates an increased risk of respiratory distress syndrome (RDS) at delivery.
L/S ratio <1.5 indicates a very high risk of developing RDS.
Babies of diabetic mothers can develop RDS with L/S ratios >2.0.

42. L/S ratio continued…
If a neonate is delivered before the lungs have had time to fully mature, neonatal respiratory distress syndrome (RDS, also called hyaline membrane disease) may result. A major element in the development of RDS is the inability of immature lungs to produce pulmonary surfactant, the lipid/protein material that reduces surface tension in the alveolar water layer and promotes uniform inflation of the lungs.

43. Pulmonary surfactant lipids
Pulmonary surfactant is rich in lecithin. Lecithin synthesis in the lung increases dramatically as the lung matures and begins producing surfactant. Because the amount of amniotic fluid and the concentration of material in it may vary between pregnancies, lecithin levels are generally expressed as a ratio against sphingomyelin, a non-pulmonary lipid whose concentration is relatively constant in amniotic fluid. Thus the lecithin level is generally expressed as a lecithin-to-sphingomyelin ratio or L/S ratio. L/S ratios of greater than 2 are rarely associated with RDS, except in complicated pregnancies (diabetes mellitus, premature rupture of membranes, etc.). L/S ratios of less than 2 indicate increased risk of RDS, but the majority of these neonates still do not develop RDS.

44. Vernix
Vernix is the waxy or "cheesy" white substance found coating the skin of newborns. It is secreted by the fetus's sebaceous glands in utero, and is hypothesized to have antibacterial properties. Vernix is the Latin word for "varnish." The vernix (or "varnish"), "varnishes" the baby.
Vernix is composed of the oil of the skin and cells that have sloughed off the fetus' skin.
The vernix is secreted by the sebaceous glands around the 20th week of gestation, presumably to protect the baby's skin from dehydration in the womb. Without the vernix, the baby would have very wrinkled skin from constant exposure to the watery amniotic fluid. The amount of vernix present decreases toward the end of gestation.

45. Vernix

46. Vernix

47. Homework
What are the types of congenital cystic Adenomatoid malformation (CCAM)? Describe the sonographic differences.
What is pulmonary sequestration and
How can it be differentiate from a type III CCAM?
What is the most recognizable feature of a Congenital Diaphragmatic Hernia? (CDH)?
List other sonographic findings of CDH, as well as possible associated anomalies.

48. Which of the following statements regarding diaphragmatic hernias is not true?
A. Most diaphragmatic hernias occur on the right side
B. A differential diagnosis for a fluid-filled mass in the lung is CCAM type 1
C. Severe diaphragmatic hernias include bowel and even liver
D. There is associated Polyhydramnios with a diaphragmatic hernia

49. Fetal lung maturity is assessed by performing amniocentesis and evaluating the amniotic fluid for
Vernix
Uric acid concentration
Meconium staining
Lecithin and sphingomyelin

50. What are the four factors that are most important for normal lung development during fetal life? Explain how we can test for fetal lung development. (Please be specific).
Are there charts for fetal thoracic circumference? If so, what are they actually measuring? Why is this important?
Explain the significance of Aortopulmonary vascular calcifications.

51. How does one diagnosis CDH with ultrasound?
Is the location of the liver in CDH of any significance? Explain.
Are there treatment options for fetuses with CCAM? Explain.

52. Are there treatment options for fetal pleural effusion? Explain.
What is bronchopulmonary Sequestration?
What is hydrothorax and what are the consequences of it?