OB test 3 Flashcards
What is the major reason why fetuses younger than 24 weeks are generally considered non viable?
Pulmonary immaturity
Fluid in lungs at birth clears by what 3 routes?
Mouth and nose
Into pulmonary capillaries
Into lymphatic and pulmonary vessels
In a normal thoracic cavity, the ribs form the ___ margins, the clavicles form the ____ margins, and diaphragm forms ___ margins
Lateral
Upper
Lower
In the presence of oligohydramnios, what may result?
Pulmonary hypoplasia
Chest circumference is measured in __ plane at level of ____ view
Trans
4 chamber view of heart
A fetus with significant narrow diameter of chest may have ___
Asphyxiating thoracic dystrophy
Central portion of thorax is occupied by the ____
Mediastinum
Apex of heart should be directed towards the ___
Spleen
Base of heart lies ___ to diaphragm
Horizontal
Abnormal position of heart may indicate ___
Chest mass
Pleural effusion
Cardiac malformation
Fetal lungs appear
Homogenous
Can US assess lung maturity?
No
As gestation increases, lung echogenicity ____
Increases
Fetal breathing becomes more prominent in what trimester?
2nd and 3rd
A mature fetus spend almost __ of its life breathing
1/3
When evaluating fetus for lung mass, sonographer should assess ___
Position of fetal heart
Orientation of cardiac axis
TC
Normal cardiac axis is at ___ degrees
45
Deviation of heart from normal axis suggests presence of
Intrathoracic mass
Lungs will not grow or develop when ____ occurs
Oligo
With a mass in thoracic cavity, heart and mediastinal structure may be ___ and lung may be ___
Displaced
Compressed
Pulmonary hypoplasia is caused by increase in numbers of ___
Lung cells
Airways
Alveoli
This type of abnormality results in lethal pulmonary hypoplasia
Kidney
Methods used to determine presence of pulmonary hypoplasia
Thoracic measurements Lung measurements Lung volume Doppler of pulmonary arteries Fetal breathing activity
What is the most common lung cyst detected prenatally?
Bronchogenic cyst
Bronchogenic cysts occurs as result of ____ and lack of communication with ___
Abnormal budding of foregut
Trachea or bronchial tree
Bronchogenic cysts usually occur within the ___
Mediastinum or lung
Do bronchogenic cysts show evidence of mediastinal shift or heart failure?
No
What is pleural effusion?
Accumulation of fluid within pleural cavity that may appear as an isolated lesion or secondary to multiple fetal anomalies
What is the most common reason for pleural effusion?
Chylothorax occurring as right-sided unilateral collection of fluid
Is hydrothorax bilateral or unilateral?
Both
Pleural effusions may occur in fetuses with ___
Chromosomal abnormalities
Cardiac mass
Lymphangiectasia
Pleural fluid is rarely encountered before ___ weeks except in association with ___ or ___
15 weeks
Down
Turners
Presence of pleural effusion may cause
Shift in mediastinal structures
Compression of heart
Inversion of diaphragm
Prognosis of pleural effusion is poorer when associated with
Hydrops
What is pulmonary sequestration?
Supernumerary lobe of the lung separated from the normal tracheobronchial tree
Pulmonary sequestration develops from
Separate outpouching of foregut or separation of segment of developing lung
In pulmonary sequestration, the extra lung tissue is functional r non?
Non functional
Pulmonary sequestration usually occur where?
Lower lobe of lung
W/ pulmonary sequestration, majority of extralobar defects occur on __ side
Left
What is CCAM?
Multicystic mass within lung consisting of primitive lung tissue and abnormal bronchial structures
CCAM lesion may involve
One of more lobes of lung
Entire lung
Or bilateral
With CCAM does is communicate with the bronchial tree or not?
It may
With CCAM, most lesions are uni or bilateral?
Unilateral and dont favor either lung
CCAM type 1 is also called
Macrocystic
