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CH. 60 The Fetal Thorax > Ch. 60-The Fetal Thorax > Flashcards

Ch. 60-The Fetal Thorax Flashcards

1
Q

What is probably the single most important determinant for fetal viability?

A

Adequacy of pulmonary development

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2
Q

What is the major reason why fetuses younger than 24 weeks of gestation are generally considered nonviable?

A

Pulmonary immaturity

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3
Q

Breathing movements before birth result in:

A

*the aspiration of fluid into the lungs

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4
Q

How much of the lungs are filled with fluid at birth?

A

About half

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5
Q

What are the 3 routes that the fluid in the lungs at birth clears by?

A

1) Through the mouth and nose 2)Into the pulmonary capillaries 3) Into the lymphatic’s and the pulmonary vessels

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6
Q

What planes is the fetal thorax examined?

A

Transverse and coronal or parasagittal planes

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7
Q

The normal shape of the thoracic cavity is:

A

*symmetrically bell shaped, with the ribs forming the lateral margins, the clavicles forming the upper margins, and the diaphragm forming the lower margin.

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8
Q

What serve as the lateral borders for the heart and lie superior to the diaphragm?

A

The lungs

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9
Q

What does the diaphragm look like on real-time sonography?

A

An echogenic smooth hypoechoic muscular margin between the fetal liver and the lungs.

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10
Q

The thorax is normally slightly _______ than the abdominal cavity, and this ratio has been reported to remain _______ throughout pregnancy.

A

smaller; constant

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11
Q

What measurements are made in the transverse plane at the level of the four-chamber view of the heart?

A

Chest circumference measurements

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12
Q

A fetus with a significant narrow diameter of the chest may have:

A

asphyxiating thoracic dystrophy

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13
Q

What type of dwarfism may be associated with asphyxiating thoracic dystrophy?

A

Thanatophoric dwarfism

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14
Q

The central portion of the thorax is occupied by the mediastinum, with the majority of the heart positioned in the:

A

midline and left chest.

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15
Q

The apex of the heart should be directed toward the _______ chest wall at an axis that is _______ degrees from the midline.

A

left; 45

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16
Q

Where does the base of the heart lie in regards to the diaphragm?

A

Horizontal to the diaphragm.

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17
Q

The location of the heart is important to document as detection of abnormal heart position may indicate the presence of: (3 things)

A
  • chest mass
  • pleural effusion
  • cardiac malformation
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18
Q

The fetal lungs appear _______ on sonography with moderate _______.

A

homogenous; echogenicity

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19
Q

Early in gestation, the lungs are similar to or slightly _______ echogenic than the liver.

A

less

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20
Q

As gestation progresses, there is a trend toward increased:

A

pulmonary echogenicity relative to the liver.

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21
Q

The lungs will not grow properly or develop properly when: (4 things)

A
  • there is a small uterine cavity resulting from severe oligohydramnios
  • when the chest cavity is abnormally small
  • when the balance b/n tracheal and airway pressure and fluid volume is inadequate
  • when the fetus is unable to practice breathing movements
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22
Q

What is pulmonary hypoplasia caused by?

A

A decrease in the # of lung cells, airways, and alveoli, with a resulting decrease in organ size and weight.

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23
Q

What does the reduction in lung volume due to pulmonary hypoplasia result in?

A

Small, inadequately developed lungs.

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24
Q

Pulmonary hypoplasia is a condition that most commonly occurs from:

A

*prolonged oligohydramnios or is secondary to a small thoracic cavity as a result of a structural or chromosomal abnormality

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25
Pulmonary hypoplasia may also occur in fetuses with severe:
IUGR and early rupture of the membranes.
26
Pulmonary hypoplasia may be caused by masses within the thoracic cavity including: (5)
* pleural effusion * diaphragmatic hernia * cystic adenomatoid malformation of the lung * bronchopulmonary sequestration * other large cysts and tumors of the lung and thorax
27
Other abnormalities resulting from pulmonary hypoplasia: (4)
* cardiac defects * skeletal dysplasias * CNS disorder * chromosomal trisomies (13, 18 & 21)
28
Sonographic findings used to determine the presence of pulmonary hypoplasia: (5)
* thoracic measurements * various lung measurements * estimation of lung volume * Doppler studies of the pulmonary arteries * Assessment of fetal breathing activity
29
What are echo-free masses that replace normal lunch parenchyma?
lung cysts
30
Lung cysts may vary in size, ranging from:
small isolated lesions to large cystic masses that may cause notable shifts of intrathoracic structures.
31
What is the most common lung cyst detected prenataly?
bronchogenic cyst
32
Where do bronchogenic cysts typically occur?
within the mediastinum or lung, infrequently they are inferior to the diaphragm.
33
How do bronchogenic cysts appear sonographically?
as small circumscribed masses w/o evidence of a mediastinal shift or heart failure --amniotic fluid volume is w/in a normal range
34
What is pleural effusion or hydrothorax?
Accumulation of fluid w/in the pleural cavity that may appear as an isolated lesion or 2ndary to multiple fetal anomalies.
35
How does pleural effusion appear sonographically?
As echo-free peripheral masses on one or both sides of the fetal heart.
36
Effusions conform to the thoracic cavity and often compress what?
lung tissue
37
The lung appears to ________ in the fluid.
float
38
Pleural fluid is rarely encountered before the ________ week of gestation, except in association with ________ or _________ syndrome.
15th week; Down or Turner syndrome
39
What may cause pulmonary hypoplasia, which often represents a life-threatening consequence for the neonate?
Compression of lung parenchyma
40
The presence of a pleural effusion may cause: (3 things)
* a shift of mediastinal structures * compression of the heart * inversion of the diaphragm
41
How does the shape of the lung appear in the presence of pleural effusion?
normal
42
What should be searched for once a pleural effusion has been discoverd? (4 things)
* lung * cardiac * diaphragmatic lesions * hydrops--ascites, scalp edema, tissue edema)
43
When the pleural effusion is large, what is impared and what may this result in?
lung development, which may result in pulmonary hypoplasia
44
Solid tumors of the fetal lungs have been reported by US, appearing as:
echo-dense masses in the lung tissue - -pulmonary sequestration - -certain types of CAMS
45
What does CAMS stand for?
cystic adenomatoid malformations
46
What is pulmonary sequestration?
A supernumerary lobe of the lung, separated from teh normal tracheobronchial tree.
47
In pulmonary sequestration, where is extra pulmonary tissue present?
Within the pleural lung sac or is connected to the inferior border of the lung w/in it's own pleural sac.
48
True or false: The extra lung tissue caused by pulmonary sequestration is functional.
False, it is nonfunctional and receives its blood supply from systemic circulation
49
The arterial supply to the extra lung tissue is usually from:
the thoracic aorta, with venous drainage into the vena cava
50
Sonographic features of pulmonary sequestration:
* echo-dense solid mass resembling lung tissue, usually in the lower lobe of the lung * the majority of estralobar defects occur on the lt. side and rarely below the diagram
51
Intralobar lesions appear:
spherical
52
Extralobar sequestration appears:
cone-shaped or triangular mass
53
What is congenital cystic adenomatoid malformation (CCAM)?
A multicystic mass w/in the lung consisting of primitive lung tissue and abnormal bronchial and bronchiolar-like structures
54
CCAM is one of the __________ ________ malformations.
bronchopulmonary foregut
55
How may forms of cystic adenomatoid malformation are there?
3--CCAM type I-III
56
What happens in CCAM type I?
One or more large cysts replace normal lung tissue--single or multiple cysts measuring more than 2 cm and up to 19 cm.
57
CCAM type II lesions consist of:
multiple small cysts--less than 1 cm.
58
CCAM type II lesions are associated with fetal and/or chromosomal abnormalities in _____% of cases including: (3 things)
* 25% | * renal agenesis, pulmonary anomalies and diaphragmatic hernia
59
How are CCAM type III malformations characterized?
As bulky, large, noncystic lesions appearing as echo-dense masses of the entire lung lobe.
60
What is differentiation of the CCAM types imperative?
B/c prognosis varies depending on the type of lesion.
61
When there is a shift of the mediastinal structures, what may happen? (3 things)
* lung compression may occur * hydrops may develop * Hydramnios may be seen due to esophageal compression, preventing normal swallowing
62
US findings when a cystic or solid lung mass has been identified, attempt to do the following: (6 things)
* Determine the # and size(s) of the cystic structure(s) * check for presence or absence of a mediastinal shift * identify and assess the size of the lungs * look for fetal hydrops * exclude cardiac masses * search for other fetal anomalies
63
What is congenital bronchial atresia?
A rare pulmonary anomaly that results from the focal obliteration of a segment of the bronchial lumen
64
Where is congenital bronchial atresia most commonly found?
In the left upper lobe and appears on US as an echogenic pulmonary mass lesion
65
What is an important muscle separating the thoracic cavity from the abdomen?
the diaphragm
66
How should the diaphragm appear in a normal fetus?
As a curvilinear hypoechoic structure coursing anteriorly to posteriorly
67
The ________ ________ and ________ should be identified _________ to the diaphragm, with the lungs and heart positioned __________.
fetal stomach and liver; caudal; cephalad. | **Failure to recognize these normal relationships should prompt you to search for diaphragmatic defects
68
When does the muscular diaphragm form?
Between the 6th and 14th week of gestation
69
The diaphragm forms as a result of a chain of events involving the fusion of four structures:
* the septum transversum * pleuroperitoneal membranes * dorsal mesentery of the esophagus * body wall
70
What is the part of the diaphragm that forms last and is the most commonly defective?
The most posterior aspect
71
What is a congenital diaphragmatic hernia?
A herniation of the abdominal viscera into the chest that results from a congenital defect in the fetal diaphragm.
72
Where does the diaphragmatic hernia permit the abdominal organs to enter?
The fetal chest
73
Where does the most common type of diaphragmatic defect occur? What percentage?
90% of defects occur posteriorly and laterally in the diaphragm--herniation through the **foramen of Bochdalek
74
Where does the diaphragmatic hernia usually found?
On the left side of the diaphragm, and the left-sided organs enter the chest through the opening.
75
The abnormally positioned abdominal organs shift the heart and mediastinal structures to the _______ side of the chest. Usually the stomach is in the chest near the heart, instead of below the ________.
right; diaphragm
76
In left-sided hernias, what should you look for to be in the thoracic cavity? (4 things)
* stomach * portions of the small and large intestines * left lobe of the liver * spleen
77
Diaphragmatic hernias may occur ________ and ________ in the diaphragm, through the ____________, and may communicate with the pericardial sac.
anteriorly and medially; foramen of Morgagn
78
What happens with the heart and stomach in anteromedial defects?
The heart may be normally positioned but surrounded by pleural fluid, while the fetal stomach may be located in its normal position in the abdomen.
79
Defects on the right side of the diaphragm allow:
the right side abdominal organs (liver, gb, intestines) to enter the chest. As a result, the lungs are compressed and may become hypoplastic
80
Sonographic findings of a left congenital diaphragmatic hernia:
* cardiac silhouette is displaced to the right and an ectopic stomach is in the chest. * apex of the heart will be abnormally shifted, depending on the size of the defect * small bowel and colon are commonly intrathoracic, but are often collapsed and difficult to specifically identify if peristalsis isn't present
81
What is very important to note in order to make the diagnosis of a hernia?
The cardiomediastinal shift
82
In a right-sided diaphragmatic hernia, you will see: (4 things)
* the liver in the chest * possibly a collapsed bowel * the heart deviated far to the left * stomach alignment will be abnormal, but inferior to the diaphragm and moved to the right.
83
The prognosis for congenital diaphragmatic hernias is poor for the fetus if: (4 things)
* if the hernia is detected before birth * the presence of the stomach is found in the chest, especially if it's dialted * if the left heart is underdeveloped * if congenital heart disease is present - -The primary cause of death is pulmonary hyplasia
84
Frequently associated abnormalities include: (7 things)
* cardiac malformations (20%) * CNS malformations (30%) * renal anomalies * vertebral defects * pulmonary hypoplasia * facial clefts * chromosomal abnormalities
85
At birth, the majority of infants with congenital diaphragmatic hernia have 2 things:
* pulmonary hypoplasia | * 2ndary respiratory insufficiency
86
What is the mortality rate b/c of the increased frequency of coexisting fetal congenital anomalies?
75%

CH. 60 The Fetal Thorax (1 decks)

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