Ch 7 Chest Flashcards
What does the normal intrathoracic contents consist of?
-Homogeneous, relatively symmetric lung parenchyma surrounding central heart
-Mediastinum
The clavicles ossify (turn into bone) as early as how many weeks?
8 wks
The scapulae ossify beginning at what week?
10 wks
Ossification of sternum begins b/w what weeks?
21-27 wks
Evaluation + assessment of fetal thorax/chest includes what?
-Observation of size/symmetry of bony + soft tissue elements
-Assess heart, pulmonary echotexture, diaphragm, bony elements for symmetry + chest size compared to abdomen
What should we be looking out for when assessing the thorax?
Asymmetry, mass, mass effect or mediastinal shift
What are the posterior elements also called?
Lamina
(there is only 1 anterior element)
Why should we examine the vertebrae?
For ensure there is convergence of the paired posterior ossified elements toward the nonossified spinous process + single anterior element
Why evaluate the posterior skin surface?
To rule out a break in the skin surface (associated with myelomeningocele)
Muscles of chest wall are hypoechoic or hyperechoic + thick or thin?
Hypoechoic + thin
List 2 reasons why soft tissues may appear thick?
-With fetal edema/swelling
-Due to subcutaneous fat deposits in infants of diabetic moms
Anterior chest wall masses (fetal breasts) can form/enlarge under the influence of what?
Maternal hormone stimulation
(can be seen in fetuses of either sex)
What type of biometry is used to rule out pulmonary hypoplasia or to assess gest age?
Thoracic circumference
How do we obtain a thoracic circumference?
-Outer to outer
-True TRV view, above diaphragm at level of heart
What would low thoracic circumference measurements indicate?
Decrease in lung volume (found with pulmonary hypoplasia)
Are all low TC/AC ratios caused by pulmonary hypoplasia?
No! Can just be a small thorax
The TRV view of chest (at level of AV valves) should show the heart taking up how much of the thorax?
One-third
(if it takes up more space, consider pulmonary hypoplasia + cardiomegaly)
Lungs begin developing in embryo as a diverticulum extending from what?
Tracheal bud
Primary bronchial buds grow laterally + become what structure?
Pleural cavity
In week 5, the bronchial buds join with the primitive trachea to form what?
The bronchi
In pseudoglandular period, the bronchi divides into secondary bronchi which forms what?
The lobar, segmental + intersegmental branches
Respiration is possible during what week due to development of terminal saccules?
Week 24
What happens in the terminal saccular period from 26 weeks to birth?
Saccules keep developing + increase ability of lungs to perform gas exchange
When is the alveloar period?
32 weeks to birth
(overlaps terminal saccular period)
When is the terminal saccular period?
26 weeks to birth
The lungs are separated by what?
The diaphragm
SF of normal lungs?
Homogeneous + symmetric
(compare echogenicity to liver + spleen in SAG/coronal)
How does the echogenicity of lungs compare to the liver?
Early gestation: lung is equal or slightly less of the liver
Later gesation: lung is greater than liver
What is the gold standard for assessing lung maturity?
Amniocentesis (u/s can not assess it)
CD imaging of lung vasculature helps rule out what?
Pulmonary agenesis
SF of diaphragm?
Thin, hypoechoic, dome shaped muscular band that separates abdominal cavities from thoracic cavity
What does the SAG plane of the upper/lower surface of the diaphragm show?
Upper surface: forms floor of thoracic cavity
Lower surface: roof of abdominal cavity
Imaging the diaphragm can help differentiate what 2 things?
Cystic intrathoracic masses from pulmonary origin VS intraabdominal origin
When in the pregnancy would fetal breathing possibly be detected by diaphragmatic motion?
As baby nears term
Location of thymus?
Posterior to sternum at level of great vessels in heart (anterior to AO + PA)
SF of thymus?
Hypoechoic structure
Do we regularly image the thymus?
No! Only if large pleural effusions present
(can assess when determining IUGR + predicting chorioamnionitis)
Location of larynx?
Fetal neck anterior to trachea, at level of 3rd-6th cervical vertebrae
When are the oropharynx + laryngeal pharynx occasionally seen?
When filled with fluid (see coronally)
Laryngeal atresia/stenosis is suspected when we see what in the trachea?
Persistently fluid filled trachea (wonder if there is an occlusion)
What is a pleural effusion?
Accumulation of pleural fluid in lungs
What is associated with pleural effusion?
-Hydrops (m/c)
-Congenital cardiac anomalies
-Chromosomal anomalies
-Polydactyly
How common are pleural effusions?
Common, makes up half of all intrathoracic abnormalities (will see in clinical)
Is a small amount of fluid in chest normal?
No! Should be NO fluid present
Is pleural effusion m/c an isolated finding?
Nope! M/c part of other fetal pathologic processes (m/c fetal hydrops)
What is fetal hydrops?
Excessive fluid accumulations in fetal soft tissues + body cavities
SF of bronchogenic cysts?
-Unilocular or multilocular
-Displaces mediastinal structures
-Found in lung parenchyma or mediastinum
(image looks like large, perfectly circular anechoic cyst in chest)
Are bronchogenic cysts common?
Nope!
Bronchogenic cysts often communicate directly with what?
Trachea or main stem bronchi
What is pulmonary sequestration?
-Solid, nonfunctioning mass of lung tissue
-Located in pleural sac
-Lacks communication with tracheobronchial tree + has a systemic arterial blood supply
How common is pulmonary sequestration?
Accounts for a quarter of lung lesions
Is pulmonary sequestration m/c in males or females?
Males (4:1 male to female ratio)
Location of extralobar pulmonary sequestrations?
Either above or below diaphragm
(has its own pleural sac + systemic venous drainage)
SF of intralobar pulmonary sequestration?
Lung mass that appears spherical, homogeneous, highly echogenic + often seen at lung base or inferior to diaphragm
(image shows large very echogenic mass in lung)
Do extralobar pulmonary sequestration massess have a good or bad prognosis?
Good! Can resolve spontaneously in utero
The determination of blood supply with CD aids in diagnosis for pulmonary sequestration + what other pathology?
CCAM (has arterial supply originating from PA)
Fetal edema may be limited to the neck, but is most commonly associated with what?
Fetal hydrops + increased soft tissue thickness
(this forms a HALO pattern around neck, thorax + abdomen)
Nuchal area edema is associated with what?
-Nonimmune hydrops
-Demise
-Skeletal dysplasias
What are cystic hygromas?
-Benign abnormalities of lymphatic origin occurring in 1 in 6,000 pregnancies
-Due to failure in development of normal lymphatic venous communication
Is fetal edema usually good or bad news?
Bad
Are cystic hygromas common?
Yes, very common in 1st trimester
SF of cystic hygromas?
-Lymphatic sacs dilate
-Unilocular or multilocular cystic masses
What is pulmonary hypoplasia?
Lack of development of lung
(usually secondary to lung compression, but can also result from abdominal masses)
A small thorax of several skeletal dysplasias is associated with what?
Lung underdevelopment
What is necessary for normal lung development?
Fluid movement due to maternal breathing + heart/body motion on chest wall
(with oligohydramnios, there is little fluid to transmit these movements which may cause pulmonary hypoplasia)
Is oligo or polyhydramnios associated with pulmonary hypoplasia?
Oligo
What is the prognosis of pulmonary hypoplasia?
-Depends on degree of hypoplasia (rarely primary cause of inadequate lung growth)
-Mortality is high with pulmonary insufficiencies due to inability of lungs to support extrauterine life
What fetuses would have erythroblastosis fetalis (severe anemia) or immune hydrops?
Fetus whose mom has been sensitized by a blood factor histoincompatibility (typically Rh factor)
Explain the immune reaction b/w mom + fetus in immune fetal hydrops?
Maternal immunoglobulin G (IgG) + fetal blood factor is not compatible
What is the result of immune fetal hydrops?
Fetal morbidity + mortality
(sm amount of ascites or pericardial effusion are signs of impending organ failure)
What can we give the mom to help protect against immune fetal hydrops?
RhoGam - can protect Rh-negative mom from incompatibility with future Rh-positive baby
Degree of fetal anemia with immune fetal hydrops can be determined through what exam?
Amniocentesis or cordocentesis
Is fetal hydrops m/c from immune or non-immune?
Non-immune
What is nonimmune hydrops from?
Variety of severe fetal diseases, NOT from incompatibility of fetal/maternal blood!!
(is also usually fatal)
SF of nonimmune fetal hydrops?
-Skin thickening
-Pleural + pericardial effusion
-Ascites
-Hepatomegaly + splenomegaly
-Thick placenta over 4cm (due to anemia)
-Polyhydramnios (warning sign of fetal distress)
What is a congenital diaphragmatic hernia (CHD)?
Defect of diaphragm that allows contents from abdomen to migrate into thorax
The opening into the pleuroperitoneal membrane with CHD may result in several different diaphragmatic abnormalities, what are they?
-Complete absence of diaphragm (uncommon)
-Protrusion of bowel through diaphragm
-Retrosternal, anteromedial herniation through foramen of Morgagni
-Posterolateral herniation through foramen of Bochdalek (M/C, over 90%), usually on left side
What accounts for the largest amount of congenital diaphragmatic hernias?
Posterolateral hernias through the FORAMEN OF BOCHDALEK!!!
(dustin will ask this)
Is left or right sided involvement more common with CHDs?
Left is 5x m/c
(liver helps prevent right sided herniation)
Are CHDs m/c unilateral or bilateral?
Unilateral 96% (left side)
Are CHDs m/c in men or women?
Men
The majority of CHD cases are due to what?
Unknown causes (half occur as an isolated defect)
Should we do an EV if we suspect a CDH?
Yes, early diagnosis is important as it affects the outcome
What organs tend to move into the chest if a posterior diaphragmatic defect is present?
Stomach, bowel, etc.
Cystic or solid abnormalities of the lung can stimulate CDHs?
Cystic - look at the abdomen to confirm absence of stomach
Will a fetus with CDH have a larger or smaller AC measurement?
Smaller
Will the heart + mediastinum shift towards or away from side of herniation?
Away
Is oligo or polyhydramnios a worse sign with CDHs?
Polyhydramnios - pleural effusions are bad too
(the smaller the herniation = better prognosis)
Are left or right sided hernias easier to see?
Left - b/c of cystic nature of stomach + ectopic presence in chest (no liver in the way)
List anomalies that mimick CHD?
-CCAM
-Pulm sequestration
-Bronchogenic cyst
-Teratomas
-Neurenteric cysts
-Bronchial atresia
Pressure from the herniated abdominal contents on the pulmonary vessels + lungs (with CDHs) can mimick an intrathoracic mass, what can this lead to?
Pulmonary hypoplasia
(can be bilateral despite a unilateral diaphragmatic lesion)
Are CDHs fatal?
Yes, 50-80% mortality rate with 35% stillbirth rate
If surgery is performed before how many weeks gestation can there be an improved prognosis for an CDH?
By 24 weeks, before lung development is complete
(it will reduce pressure + avoid pulmonary hypoplasia from forming)
Will a liver in an abdomen survive if there is a CDH?
Yes, 90% survival
What does CCAM stand for? How many types are there?
-Congenital cystic adenomatoid malformation
-3 types
What is the m/c identified mass in fetal chest, when excluding diaphragmatic hernias?
CCAM
Do CCAMs m/c involve a part of a lobe OR an entire lobe?
Entire lobe (usually unilateral)
Which part of the lobe do CCAMs occur in?
Upper lobe
What do CCAMs consist of?
A pathologic mass on the lung consisting of multiple cysts of different sizes
What does type 1 CCAM consist of?
Single cyst or multiple large cysts (2-10cm in diameter) with a trabeculated wall + smaller cystic outpouchings
What does type 2 CCAM consist of?
Multiple, uniform sized cysts (0.5-2cm in diameter)
What does type 3 CCAM consist of?
-Multiple microscopic cysts (0.5-5.0mm)
-Similar to PKD
-B/c they are so small, it will appear as a single solid homogeneous echogenic mass
80% of neonates who survive with CCAM present with what at birth?
Respiratory distress
Pt’s with CCAM type 2 may have what types of associated malformations?
-Renal
-Cardiac
-Gastrointestinal
Fetuses with CCAM may present with what conditions due to the compression on the lung?
-Hydrops
-Ascites
-Polyhydramnios
Will a CCAM cause in increased or decrease in thoracic diameter?
Increase - plus inversion of diaphragm
Which type of CCAM is worst?
Type 3 - is more extensive as it is solid appearing
(types 1 + 2 have better prognosis)
Which type of CCAM is m/c?
Type 1
SF of type 1 CCAM?
-Unilateral pulmonary/lung mass
-One or more large cysts
SF of type 2 CCAM?
-Echogenic mass
-Small cysts
SF of type 3 CCAM?
Solid, homogeneous echogenic mass
(worst prognosis b/c not cystic)
During which trimester is CCAM detected?
2nd
During which trimester does CCAM begin developing?
1st trimester
Due to mass effect of CCAM, what do some fetuses demonstrate?
-Ascites
-Pleural effusion
-Hydrops
-Inversion of diaphragm
How can CD help us differentiate a CCAM from pulmonary sequestation + diaphragmatic hernias?
CCAM: CD identifies arterial supply via pulmonary vessels
Sequestration + hernias: do NOT demonstrate vascularity with CD or power doppler
Will CCAMs show flow + vascularity?
Yes!
Can CCAMs disappear on its own?
Some can, most baby’s need operation once born
