Congenital diaphragmatic hernia (CDH) occurs when abdominal organs herniate into the chest cavity due to a failure of the diaphragm to fully form. This causes pulmonary hypoplasia and decreased lung growth. The pathogenesis involves decreased pulmonary blood flow and alterations to the surfactant system. The most common types are Bochdalek and Morgagni hernias. Right-sided CDH is associated with worse outcomes such as need for nitric oxide and longer term breathing support. Autopsy and MRI can be used to further characterize CDH anatomy and effects.

1. Pathogenesis of CDH and
anatomic findings

2. What is CDH ?
Failure of diaphragmatic fusion
Hernitation of abdominal contents into
thoracic cavity
Pulmonary hypoplasia

3. Causes
Genetics
Harmful environmental exposure
during pregnancy
Fetal malnutrition

4. Pathogenesis of CDH
pulmonaryhypoplasia due to decrease in cross-sectional area
of the pulmonary vasculature and alterations of the
surfactant system
The lungs have a small alveolar capillary membrane for gas
exchange, which may be further decreased by surfactant
dysfunction
There is increased muscularization of the intraacinar
pulmonary arteries
In very severe cases, left ventricular hypoplasia is observed.
Pulmonary capillaryblood flow is decreased because of the
small cross-sectional area of the pulmonary vascular bed, and
flow may be further decreased by abnormal pulmonary
vasoconstriction.

5. Types of congenital diaphragmatic hernia
Bochdalek hernia: A left-sided CDH
(present in ~83% of babies)
Morgagni hernia: right-sided CDH
(present in ~17% of babies)
The hiatus hernia

6. left vs. right CDH
In right CDH, the liver is more likely to move up into the chest
where the baby’s lungs should be growing.
The timing of surgery to repair the CDH was later in babies with
right-sided defects.
Babies with right CDH are more likely to need treatment with
nitric oxide.
Right CDH babies are also more likely to need medications to keep
their lungs relaxed after discharge.
In right CDH, there is a greater likelihood of needing
supplemental oxygen at the time of discharge, and more of a
chance of needing a tracheostomy for long-term breathing
support.

7. Total fetal lung volume can be calculated on MR by tracing the lung area (cyan solid arrow) on
consecutive images, summing the areas, and multiplying by slice thickness. Postprocessing software
may also be used (liver (white open arrow), stomach (cyan curved arrow)).
Sagittal T2 MR shows herniated liver (white curved arrow) through a small anterior foramen of
Morgagni. These are rare in fetuses and are an exception to the "liver up is bad" rule. Note that the
herniated liver is having little effect on the lung (white open arrow).

8. Autopsy in a different case shows both small bowel (white curved arrow) and liver (cyan open arrow) herniated into the left chest via a posterior diaphragmatic defect. The left lung (cyan curved arrow) is
superiorly displaced, and the heart (white open arrow) is in the right chest. Note the anterior diaphragm (black solid arrow) is intact.