1. Ultrasound evaluation of
fetal thorax
Dr.N.Suriyaprakash

2. EMBRYOLOGY OF FETAL LUNGS
• Intact pulmonary system is not required for
intrauterine viability but the prenatal
development of the respiratory system is integral
to ex utero life and survival.
• Structural development - Branching of the
airways and development of alveolar spaces
• Functional development - Creation of a
surfactant system  decrease alveolar surface
tension  inhibits alveolar collapse during
exhalation
Surfactant system typically mature at 36 weeks gestation. Birth
prior to this results in neonatal respiratory compromise

3. ASSESSMENT OF THORACIC STRUCTURES
• Evaluation of lung structure and appearance
- Homogeneous with no fluid collections
• Size of the thorax relative to the fetal abdomen
• Overall chest size relative to the size of the heart
structures
• Cardiac circumference should be approximately
50% of the thoracic circumference
• Abnormal cardiac axis or abnormal position
within the chest may be a marker for
displacement by a chest mass or a missing
portion of the lung

4. Diaphragm
• Diaphragm will appear echolucent on
ultrasound images
• Adequate evaluation of the diaphragm requires
sweeping side to side to assess continuity of
the structure.
• Care should be taken to examine the
posterolateral portions.
• The contour of the diaphragm should also be
assessed, as some abnormalities may be
associated with eversion of the diaphragm
downward.

6. PULMONARY HYPOPLASIA
• Incomplete development of unilateral or bilateral
lung tissue
• C/F - respiratory compromise
– Degree of reduction in lung size
– Reduction in the number of lung cells/alveoli
– Reduction in degree of bronchial branching
• Normal lung development
– Adequate thoracic space
– Sufficient distension of lungs through fluid
exchange - reduced fetal breathing movement
and loss of fetal lung fluid into amniotic fluid

7. • Decreased thoracic space
– Space occupying lesions - CDH, CPAM, massive
cardiomegaly, and pleural effusion
– Thoracic MSK abnormalities - skeletal dysplasias
and neuromuscular disorders
• Insufficient distension of lungs through fluid
exchange
– Oligohydramnios - renal or urinary tract abnormalities
– Preterm premature rupture of membranes

8. • Pulmonary hypoplasia  high mortality
rate  prenatal prediction is critical for
appropriate counseling
Subjective ultrasound
assessment of relative
chest size is helpful
only in extreme cases

9. • Fetal thoracic circumference
• Thoracic length
• Thoracic circumference to abdominal
circumference (TC/AC) ratio
• Lung-to head ratio (LHR)
• Quantitative Lung Index (QLI)
–Lung area/(head circumference/10)2
– Fetal age independent
Indirect measurements of lung volumes do not
reliably and uniformly predict pulmonary hypoplasia,
lung function, or likelihood of survival
2D measurements

10. • 3D ultrasound to obtain volume measurements
either directly or through the VOCAL technique.
• MRI
– To calculate lung volumes
– More clearly delineating lung tissue from
mediastinal structures
– Not compromised by limitations of
ultrasound in the presence of oligohydramnios
or high maternal body mass index (BMI).
– Ability of MRI to predict prognosis and
survival has also been inconsistent.

12. • Pulmonary hypoplasia need prolonged
respiratory support and can result in infant death
despite aggressive postnatal management.
• Sonography nor MRI uniformly predicts
hypoplasia except in extreme cases
• Measurements obtained from both modalities 
assist predicted range of disease severity 
appropriate counseling

13. Congenital Pulmonary Airway Malformation
• MC lung lesions identified by fetal ultrasound
imaging
• Unilateral
• Right = left lungs . lower lobes MC affected.
• Pathogenesis – Maturational arrest in
bronchopulmonary development, resulting in
dysplastic tissue distal to this segment
• Communicate with the normal tracheobronchial
tree
• Blood supply - normal pulmonary circulation

14. Stockers classification
• Type 1 - Lesion with a dominant cyst (3-10 cm in
diameter)
• Type 2 - Multiple small cysts (0.5-2.0 cm
diameter) that are distributed evenly and blend in
with adjacent normal tissue
• Type 3 - Small microcyst or what appears to be
solid type of cyst on sonographic images
• Type 0 - Acinar dysplasia
• Type 4 - Large peripheral cyst of the distal acinus
lined with alveolar cells
Microcystic or macrocystic and to report its size

15. A, Macrocystic congenital pulmonary airway malformation, type 1, with several sizable
cysts in the left-sided chest mass. B, Echogenic congenital pulmonary airway
malformation, type 2, within the chest, displacing the heart. Small peripheral cysts are
seen. C, Displacement of the fetal heart toward the right facilitates identification of
homogeneous left-sided mass. The solid-appearing mass is consistent with congenital
pulmonary airway malformation, type 3. No discrete cysts are seen. Small amount of
normal-appearing lung is present on the right. LT, left thorax; RT, right thorax

16. Large solid and cystic type 2
congenital pulmonary airway
malformation shown on axial (A)
and coronal (B and C) views. Note
the small amount of ascites
present at the upper abdomen.
There is marked leftward
displacement of the heart (H). S,
stomach

17. Homogeneous, echogenic chest mass shown in axial (A) and sagittal (B) views,
consistent with type 3 congenital pulmonary airway malformation

18. 1) Shift in the location or axis of the fetal heart
2) Increased echogenicity of affected lung with
possible presence of discrete cysts
3) Polyhydramnios in the later stages of pregnancy
- decreased swallowing of amniotic fluid due to
esophageal compression or increased fluid
production by the abnormal lung
4) Larger masses - Risk of fetal hydrops

19. Fetus with homogeneous echogenic lung mass and polyhydramnios

20. Prognosis
• Size of the lesion
• Presence of mediastinal shift
• Variable growth behavior
• Presence of a dominant cyst
• Fetal hemodynamic alterations
• Outcome is most closely related to the size
of the mass, attempts have been made to
quantify lesion size to provide prognosis.
• In calculating CVR, include the margins of the
lesion and to measure its maximal dimensions
CVR = (length ×width × depth × 0.52) / HC

22. • Volume of the lesion relative to the size of the
fetus(CVR) is the best predictor of both prenatal
development of hydrops and the presence of
respiratory symptoms at birth.
• Hydrops is associated with close to 100%
mortality rate and is considered an indication for
prenatal therapy
CVR >1.6 is risk for fetal hydrops
CVR > 1.0  respiratory symptoms at
birth and an increased risk of requiring
neonatal surgical intervention

23. Management
• Open fetal surgery - preterm labor, preterm rupture of
membranes, fetal demise, and potential maternal
complications
• Cyst aspiration - to slow disease progression
• Thoracoamniotic shunting – increases overall survival
rate
CPAMs tend to stabilize in size in the late second/early
third trimester (mean GA 26 weeks)

24. • Prenatal administration of corticosteroids is an
effective alternative to the invasive surgical
approach.
– Reversal of hydrops is reported in 78% of cases
– CVR >1.6  hydrops did not develop
• observation for signs of lesion growth or
development of hydrops with serial scans every 2
weeks
• CVR > 1.6  weekly assessment
• If a single dominant cyst is noted in the setting of
hydrops or decompensation  percutaneous US
guided drainage

25. Bronchopulmonary sequestration
• Mass of nonfunctioning lung tissue that does
not communicate with the bronchial tree.
• Aberrant systemic arterial blood supply
arising from the descending thoracic aorta
• Intralobar - same pleural covering as normal
lung tissue
• Extralobar – MC . distinct and separate pleural
covering.
• Extralobar lesions may occur within the
abdomen, appearing as echogenic masses
below the diaphragm.

27. BRONCHOGENIC CYST
• Result from abnormal budding of the primitive
esophagus and tracheobronchial tree during
embryogenesis
• Between 4 and 8 weeks gestation
• MC location - lung parenchyma - lesion arises
after separation of the airway and the
esophagus
• Mediastinum – lesions arising before or during
the separation of the embryonic foregut
• Cyst wall - Ciliated epithelium and contains
structural elements of the airway,

28. • Single anechoic unilocular cyst located in
the central area of the lung parenchyma.
Bronchogenic cyst (arrow) in fetus at 28 weeks’ gestation, shown in longitudinal (A)
and transverse (B) planes and transverse image with power Doppler sonographic
evaluation (C).

29. • Right-sided, near the midline, and in close
proximity to the tracheobronchial tree
• Size varies - 2 to 10 cm in diameter
• Bronchogenic cysts  enlarge with advancing
gestation  cause compression of surrounding
normal lung parenchyma  hydrops and
pulmonary hypoplasia.

30. Management
• Inutero aspiration of the cyst
• Thoracoamniotic shunting
• Closely followed and managed in the neonatal
period with thoracotomy and cyst excision.
• Wedge resection, segmental resection, and
lobectomy have been described to improve
neonatal respiratory status

31. Differential Diagnosis
1. Neurenteric cyst
• Posterior enteric remnants that result from
incomplete separation of the notochord from
the foregut in the 3rd to 4th weeks of
embryogenesis
• 90% - Right posterior mediastinum,
• 50% - Vertebral abnormalities such as scoliosis,
segmentation abnormalities with hemivertebrae,
and butterfly vertebrae
Neurenteric cysts can be distinguished from the other
cystic lesions discussed based on their association
with vertebral anomalies.

32. 2. Macrocystic CPAM with a single
dominant cyst
• Location
• Absence of surrounding echogenic lung
tissue characteristic of CPAM will aid in
reaching the correct diagnosis.

33. • Localized atresia or stenosis of a segmental bronchus.
• Mech: Focal obliteration of proximal segmental or
subsegmental bronchus, with normal development of
the distal structures.
• Prenatally diagnosed CLE can be caused by lobar
bronchial atresia
• Short atretic segment leads to mucous accumulation
within the distal bronchi, resulting in a bronchocele
BRONCHIAL ATRESIA

34. • Extremely large, massively overexpanded
unilateral lung or lung segment.
• Mass results in mediastinal shift and
compression of chest structures and often
with eversion of ipsilateral hemidiaphragm.
• Contralateral lung volumes may appear small.
• Branching fluid-filled structures within the
enlarged echogenic lung, representing dilated
airways peripheral to the central obstructed
Sonographjic findings

35. Color Doppler images through fetal chest. Axial (A) and sagittal (B) images demonstrate
markedly enlarged echogenic lung, with eversion of the hemidiaphram, consistent with
bronchial atresia. Note fluid-filled airway

36. • Serial sonograms
– To delineate anatomy
– Assess for enlargement of the lesion
– Development of hydrops
– Search for possible concomitant anomalies.
• MRI
– Helpful to identify the atretic airway
– To distinguish this lesion from a large CPAM
– Assisting with tissue characterization
– Determining level and location of atresia
– Delineating complex anatomy

37. Coronal fetal magnetic resonance images showing unilateral hyperexpanded left
lung. Note the left perihilar T2-weighted hyperintense structure consistent with a
dilated, fluid-filled airway

38. Bronchial atresia and CPAM
• Large echogenic lung appears very similar to
microcystic (type 3) CPAM
• Central versus peripheral location of cystic
components
• Involvement of multiple lobes of the lung
should raise suspicion for bronchial atresia
• BA typically enlarge during pregnancy
• Risk of hydrops is increased with larger
lesions, but the ability to prognosticate
based on lesion size is not very reliable with
bronchial atresia

39. • Bronchial atresia  segmental or
subsegmental bronchi  asymptomatic or
may not present until adolescence.
• Optimal management for a fetus with mainstem
bronchial atresia remains uncertain
• Fetus with bronchial atresia be delivered in a
tertiary care center because of pulmonary
hypoplasia and potential for air trapping in the
alveoli supplied by the affected bronchi

40. • When a larger lesion is noted, ex utero
intrapartum treatment (EXIT) and a
primed extracorporeal membrane
oxygenation (ECMO) circuit may be
considered for delivery.
• Overall prognosis remains poor for the
larger lesions identified by massive
unilateral hyperplasia, marked distention
of the obstructed bronchi, bronchiectasis,
as well as fluid filled air spaces seen at the
time of postnatal surgery

41. • Developmental abnormality of the lower respiratory
tract that is characterized by entrapment of fluid in
the lungs, resulting in hyperinflation of one or more
of the pulmonary lobes.
Bronchi are underdeveloped or obstructed
Collapsed distal lung
Prohibits normal lung fluid homeostasis.
Progressive lobar hyperinflation.
CONGENITAL LOBAR EMPHYSEMA

42. • Extrinsic compression - aberrant
cardiopulmonary vasculature or other
intrathoracic lesions like anomalous pulmonary
venous return, duplication cysts, teratomas, or
bronchogenic cysts  altered distal
development and diffuse bronchial abnormalities
• Bronchial atresia with an atretic portion of the
bronchus
• Intrinsic obstruction - defects in the bronchial
wall, such as deficient or dysplastic bronchial
cartilage  obstruction of the lower airway
CAUSES

43. • Postnatally  “ball-valve” mechanism 
greater volume of air enters the affected lobe
during inspiration than leaves during expiration 
trapping in distal areas of the lung 
emphysema.
• Upper and middle lobes and unilateral.
• Lower pulmonary tissue is typically normal in
appearance
• Blood supply is derived from the normal
pulmonary artery and vein.
• CLE is most often diagnosed in the neonatal
period secondary to respiratory symptoms

44. • Homogeneous echogenic lung mass,
usually without cystic components.
• Unilateral lesion because of the inflated lung
distal to the obstruction.
• Mass often crosses the midline and results in
displacement and compression of the heart.
• Mediastinal shift, polyhydramnios, and fetal
hydrops can also be seen and are predictors
of severe respiratory distress and increased
risk of death.

45. Differential Diagnosis
• CPAM
– Dilated fluid-filled airways will not be seen in CPAM.
– Demonstrates a plateau or gradual decrease in lesion
size after 26 weeks’ gestation
• BPS - anomalous arterial supply arising from the
aorta
• Unilateral bronchial atresia – Fetal MRI may
help confirm and delineate the underlying
pathologic proces
Appropriate treatment of CLE in neonates with
respiratory distress is surgical resection of the
affected lobe

46. • Results obstruction of the fetal upper airway
• Causes
– Laryngeal agenesis, subglottic stenosis or
atresia, and laryngeal webs or cysts
– Tracheal atresia occurs secondary to deficient
recanalization of the upper airway at about the
10th week of gestation . complete atresia is ass
with trachea-esophageal fistula
CHAOS

49. • Spontaneous resolution of the ultrasound
findings result from spontaneous perforation
of an obstructing web with decompression of
the lungs as the fluid is released into the
amniotic cavity.
• Resolution of the ultrasound findings is not
always associated with improvement in lung
function.

50. Coronal T2-weighted fetal MR images showing enlarged bilateral lungs with
eversion of the diaphragm and fluid-filled trachea (arrow) consistent with
congenital high airway obstruction syndrome, owing to laryngeal atresia.
Associated hydrops with moderate volume of fetal ascites is evident

51. Associations
• Isolated unilateral lung agenesis
• Fraser syndrome – AR with microphthalmia,
cryptophthalmos, polydactyly, and syndactyly in
association with upper airway obstruction
• Cri du chat syndrome
• Short-rib polydactyly syndrome
• 22q11.2 deletion syndrome
Thorough anatomic survey identifying additional
findings allows for optimal counseling regarding
anticipated prognosis and inheritance implications for
future pregnancies

52. Transverse ultrasound image shows marked deviation
of the fetal heart toward the left. The right lung
appears enlarged and echogenic, suggesting
unilateral bronchial atresia
Coronal T2-weighted fetal MRI of
unilateral bronchial atresia with marked
enlarged right lung. Distended
fluid-filled airway seen centrally (arrow).
Associated hydrops with marked fetal
ascites. The contralateral left lung was n
visualized

53. Differential Diagnosis
• Bilateral CLE
• Bronchial atresia
• Bilateral CPAM
• Extrinsic causes of tracheolaryngeal
obstruction – lymphatic malformation,
cervical teratoma, and vascular rings

54. • Higher mortality rate
• Prediction is crucial
• Volume – 2D/3D US or MR
Pulmonary
Hypoplasia
• Rare and Unilateral
• Communicate with the normal
tracheobronchial tree with normal pulmonary
circulation
• Micro/Macrocystic and mention the size
• Calculate CVR  Prognosticate
CPAM
• Extremely large, massively overexpanded
unilateral lung or lung segment with mass
effect
• Branching fluid filled structures within
echogenic lung
Bronchial
atresia

55. • Single anechoic unilocular cyst
located in the central area of the lung
parenchyma
• Rt side near the midline close to TBT
Bronchogenic
cyst
• B/L sym enlarged hyperechoic lungs
• Dilated fluid filled trachea
• Eversion of diaphragm
CHAOS
• Abnormality of distal respiratory tract
• Unilateral homogeneous echogenic
lung mass with mass effect
• Bronchial atresia
Congenital
Lobar
Emphysema

56. CONGENITAL HYDROTHORAX
• A/K/A primary pleural effusion,
• abnormal accumulation of fluid in the pleural
space
• As fluid increases  mass effect 
compression of adjacent thoracic structures 
compromising heart function as well as lung
development.
• Primary hydrothorax as a cause of nonimmune
hydrops should be suspected with a very large,
unilateral effusion or markedly asymmetric
bilateral effusions

57. Causes for congenital pleural effusions
• Primary chylothorax,
• Infection
• Congenital heart disease
• Genetic or chromosomal abnormalities,
• Pulmonary lesions including CPAM, or
CDH or tracheoesophageal fistula
• Hydrops fetalis.
• The two most commonly associated
abnormalities are cdh and trisomy.

60. • Isolated pleural
effusions are
differentiated
from pericardial
effusions by the
extension of fluid
around the lung
structures

61. Sonographic findings range
from small amounts of fluid
adjacent to the normal-
appearing lung (typically
more prominent in
the anterior chest) to larger
effusions causing
mediastinal shift and
downward displacement of
the diaphragm

62. • worse prognosis is associated with
bilateral effusions, the presence of
hydrops, persistence of effusions, or
premature delivery

65. • Cystic or fluid-filled structures within the
thorax such as CDH, cystic CPAM,
bronchogenic cyst, and pericardial fluid

66. CONG DIAPHRAGMATIC HERNIA
• Absence or deficiency of a portion of the
diaphragm owing to incomplete formation of the
structure, with subsequent herniation of
abdominal contents into the fetal chest
• 85% of the defects are posterolateral and on the
fetal left side

67. • Embryology : normal primitive diaphragm is
formed by the end of the 8th week of gestation
with development of the muscular diaphragm
completed by the 14th week.
• Failure of fusion of the pleuroperitoneal canal -
early in gestation, the herniation of intra-
abdominal contents may not occur until later in
fetal life, making small defects difficult to identify
early in pregnancy.
• Detected at the time of the 18- to 20-week fetal
anatomy sonogram

68. • Abnormal position of the fetal heart that
provides the first clue to the presence of a
diaphragmatic defect
• Left-sided lesion - shift of the mediastinum and
heart toward the right
• Right-sided lesion – heart may be in usual
location
Clue 1 : Position of the fetal heart

69. • Presence of the fluid-filled stomach in the chest
is easily recognized
• Bowel-containing CDH with normal-appearing,
normally located stomach  challenging
• Inability to visualize fluid filled stomach
– Oesophageal atresia
– CDH
• Location of the stomach is also helpful in
assessing the severity and the presence of other
herniated abdominal contents
Clue 2 : Stomach position

70. • Clue 3 : Polyhydramnios frequently
accompanies CDH but is usually a late finding
• Clue 4 :
• Paradoxic motion of the hemidiaphragm with
fetal breathing movements is diagnostic of a
diaphragmatic abnormality
• Descent of one hemidiaphragm with ascent of
the other
• Observed on coronal imaging during fetal
inspiration

73. • Assessment of the location of the fetal liver is
necessary for providing prognosis and patient
counseling.
• Liver herniation - higher rate of postnatal
mortality as well as morbidity.
• Left hepatic lobe is likely herniated into the
– fetal stomach is located posteriorly within the
chest.
– deviation/distortion of the midhepatic portion
of the umbilical vein to the left
Herniation of fetal liver

74. • altered hepatic venous anatomy can be
differentiated from an intrahepatic persistent
right umbilical vein by assessing the location
of the gallbladder

79. Eventration of the diaphragm
• Eventration of the diaphragm may appear as
herniation of intraabdominal contents into the
fetal chest and can be mistaken for CDH.
• Eventration results from failure of
muscularization of the otherwise intact primitive
diaphragm
• Better prognosis.