Diagnostic ultrasound ( PDFDrive )

1258 PART IV Obstetric and Fetal Sonography
FIG. 36.11 Pericardial Effusion. Note how the lungs (arrows) are
compressed posteriorly in the fetal chest by the effusion surrounding
the heart.
Case reports of other treatment options include pleurodesis
and intrapleural injection of autologous blood, which yield a
survival rate of 80%. 155,156
PERICARDIAL EFFUSION
In contrast to pleural efusions that surround the lungs and
compress the tissue medially, pericardial efusions are anteromedial
luid collections. Fluid collections of up to 2 mm in
thickness are common, and a small amount of pericardial luid
(up to 7 mm, in isolation) can be a normal inding. 157 A large
pericardial efusion compresses the lungs against the posterior
chest wall (Fig. 36.11). he heart is visualized as “loating” within
the anterior thoracic luid collection.
PULMONARY LYMPHANGIECTASIA
Pulmonary lymphangiectasia is a congenital obstruction and
dilation of the pulmonary lymphatic system. he lungs become
enlarged and stif, with development of efusions that can result
in respiratory failure. here are primary and secondary forms
of pulmonary lymphangiectasia. he secondary form is caused
by congenital heart diseases that result in poor venolymphatic
return. 158-160 Ultrasound indings can be subtle with pleural
efusions and heterogeneous lung parenchyma (Fig. 36.12). he
use of echocardiography is important to exclude cardiac
anomalies.
Fetal MRI demonstrates pleural efusions and lung heterogeneity.
Tubular T2-hyperintense branches may be present radiating
from the hila. A heterogeneous pattern referred to as the “nutmeg
lung” (Fig. 36.12C) provides a more speciic diagnosis. 161
Postnatal management includes restriction of dietary fats,
pleural efusion drainage, pleurodesis, and thoracic duct ligation.
Recent experimental treatment using ethiodized oil to embolize
the patulous pulmonary lymphatics has shown some success. 162
CONGENITAL DIAPHRAGMATIC
HERNIA
CDH results from failure of the pleuroperitoneal canal to close
at the end of organogenesis. 163 A “dual hit” hypothesis suggests
that the defect arises in the embryologic period (irst hit), and
during further gestation, lung development is impaired (second
hit). 164 he defect in the diaphragm allows herniation of viscera
into the chest. Mass efect from visceral organs in the chest has
an adverse impact on the normal development of the fetal cardiac
and pulmonary systems. hus CDH is associated with substantial
morbidity and mortality. 165-168 he incidence of CDH is about 1
in 3000 births.
CDHs can be classiied based on location; types include
posterolateral Bochdalek hernia (70%-75%), anterior Morgagni
hernia (23%-28%), and central defects (2%-7%). Most CDHs
(85%-90%) are let sided, 10% to 15% are right sided, and only
2% are bilateral. 169-173 Complete agenesis of the diaphragm,
herniation of the central tendinous part, pericardial hernia,
membrane-covered hernias, and eventration of the diaphragm
are rarer manifestations. 173
Ultrasound indings of CDH include presence of stomach
bubble, gallbladder or bowel within the thoracic cavity, deviation
of the heart and mediastinum, herniated liver, abnormal position
of the umbilical and hepatic veins, pleural efusion, and polyhydramnios.
170,174,175 he abdominal circumference is oten small,
with a scaphoid shape of the abdomen secondary to displacement
of viscera into the chest. 176
Let-sided CDH is most oten diagnosed when the stomach
is in the chest near the let atrium, with absence of the normal
stomach below the diaphragm (Fig. 36.13, Videos 36.3 and
36.4). Small and large bowel as well as the liver, spleen, and
kidney can herniate into the thorax. As the abdominal contents
herniate into the chest, mediastinal shit occurs with the heart
deviating to the right. 9,172,177 In large hernias, mediastinal shit
is severe, leading to vascular compromise. Compression of the
heart, impaired swallowing, and partial obstruction of the
gastrointestinal tract lead to polyhydramnios, which is present
in up to 69% of cases, particularly late in gestation (by the third
trimester). 165,178,179
Prenatal sonographic diagnosis of CDH can be made as
early as the irst trimester. 180-182 Detection rate sonographically
in centers with screening programs is as high as 74%, with an
increased detection rate when CDH is associated with other
anomalies. 183
At times, a let-sided hernia will be present with the stomach
in the abdomen and only small bowel loops in the chest. Real-time
ultrasound can demonstrate peristalsis of the bowel in the chest.
Paradoxical movement of abdominal contents during fetal
inspiration on real-time sonogram may help to conirm CDH,
along with traditional sonographic indings. 166
In most let-sided hernias the let lobe of the liver herniates
into the chest. he diagnosis of liver in the chest is made by
direct visualization of the liver (Video 36.5). At times, sonographic
detection of intrathoracic liver is diicult because of the liver’s
isoechoic appearance with the fetal lung. In these cases,