chapter 61 fetal thorax Flashcards
single most important determinant for fetal viability
adequacy of pulmonary development
the major reason why fetuses younger than 24 weeks gestation are generally nonviable
pulmonary immaturity
breathing movements that occur before birth result in
aspiration of fluid into the lungs
the lungs at birth are about ____ filled with fluid from amniotic cavity
half-way filled
the fluid in the lungs at birth clears via 3 routes:
- through the nose/mouth
- into pulmonary capillaries
- into the lymphatics and pulmonary vessels
normal thoracic cavity is symmetric and ____ shaped
bell shaped
the lungs serve as lateral borders for the hear and lie ____ to the diaphragm
superior
the diaphragm can be seen as a _______ curvilinear margin
smooth hypoechoic/sonolucent
normally the fetal thorax is slightly _____ than the abdominal cavity
smaller
the ratio of thoracic cavity(TC) and abdominal cavity(AC) is ______ throughout pregnancy
constant
oligohydramnios can result in _______
pulmonary hypoplasia
thoracic circenference is measured in the ____ plane at the level of the _____
transverse
4 chamber heart
a fetus that has a significantly narrower chest diameter may have _____
asphyxiating thoracic dystrophy
the majority of the heart is positioned in the midline and ____
left
the apex of the heart should be directed toward the ____
spleen(left)
detection of abnormal position of the heart may indicate:
- chest mass
- pleural effusion
- cardiac malformation
fetal lungs appear:
homogeneous with moderate echogenicity
fetal lungs: echogenicity _____ as pregnancy progresses
increases
fetal breathing becomes more prominent in the ____
2nd and 3rd trimesters
a matrue fetus spends almost _____ of its time breathing
1/3
color doppler may be used to detect fetal breathing through ___
the nostrils
when evaluating fetus for lung mass, you must note:
- position of heart
- orientation of cardiac axis
- measurement of thoracic circumference
deviation of heart from the normal axis may suggest presence of
intrathoracic mass
caused by a decrease in the number of lung cells, airways, and alveoli
pulmonary hypoplasia
pulmonary hypoplasia results in
decreased organ size and weight, small undeveloped lungs
pulmonary hypoplasia most commonly occurs from
prolonged oligohydramnios or secondary to small thoracic cavity resulting from structural/chromosomal abnormality
_____ abnormalities may result in lethal pulmonary hypoplasia
kidney
abnormalities that may cause pulmonary hypoplasia
- cardiac defects
- skeletal dysplasias
- CNS disorders
- Trisomy
________ pulmonary agenisis or hypoplasia is rare
unilateral
every fetus with mediastinal shift and chest mass, the differential should include
absent lung
prognosis for pulmonary hypoplasia: ____% die after birth
80%
severity of pulmonary hypoplasia depends on
when it occurred during pregnancy
thoracic circumference below the ____ percentile suggests pulmonary hypoplasia
5th