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Diaphragmatic Hernia
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This is a congenital defect of the closure of the diaphragm, which is the muscle
that separates the abdominal and chest cavities.
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Types
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There are two main types, which are easily distinguished:
- Posterior diaphragmatic hernia - this is the more common type and it is known as
Bochdalek hernia. Here the posterior (rear) part of the diaphragm, where the diaphragm
should connect to the peritoneum in the abdomen, fails to close. This hernia occurs
on the left side of the chest 7 times more frequently than on the right. Its frequency
is approximately 1 in every 7,000 births.
- Anterior diaphragmatic hernia - this is very rare, with a frequency of 1 in every
1,000,000 births. It is also known as Morgani hernia. Here the right side of the
diaphragm fails to connect with the left side.
A hernia must be distinguished from a condition in which the diaphragm is paralyzed
and the abdominal organs ascend but do not enter the chest cavity. This condition
does not require surgical intervention but the cause should be investigated, and
intervention and prognosis determined accordingly. Some of the causes can be severe
conditions, such as a severe systemic muscle disease like congenital myotonic dystrophy, or milder conditions such
as transient paralysis of the phrenic (diaphragmatic) nerves occurring as a birth
complication.
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Clinical signs
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Posterior diaphragmatic hernia - intestinal loops, and sometimes other organs such
as the liver, enter the chest cavity, displacing the chest organs to the contralateral
side (usually to the right, as noted).
The severity of the condition depends on the number of organs entering the chest
cavity since the pressure they put on the lungs interferes with the development
of those organs.
The appearance of polyhydramnios
indicates very high pressure in the chest and a very poor prognosis.
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After birth the baby develops respiratory distress. In mild cases this only appears
after 24 hours, after feeding the baby - this is because of the expansion of the
intestines due to the intake of food. In these cases the prognosis is better. The
severe cases are marked by early, severe respiratory distress and the appearance
of complications such as a tear in the lungs and pneumothorax, a condition where
air escapes into the chest cavity and causes additional disruption to the expansion
of the lungs and breathing. In this situation the air must be removed by inserting
a tube into the chest cavity surrounding the lungs. This must be performed as early
as possible, but only when the baby's general condition is stable. Induction of
premature birth in cases detected in pregnancy is not beneficial and may exacerbate
the respiratory problem.
About 50% of these operations are successful, but mortality is 50%. Mortality reaches
90% if there is polyhydramnios. Recently, attempts have been made in the USA to
operate on fetuses in the uterus, and the results up to now in animals have been
encouraging. This should prevent the disruption to the development of the lungs
caused by the pressure on them of the abdominal organs in the chest cavity. Some
researchers consider this condition to be the first model for a successful intrauterine
fetal operation. Associated defects occur in approximately 30 of cases and include
defects in the gastrointestinal tract,
neural tube defects (NTD),
heart defects, etc. Chromosomal problems occur in approximately 4% of
cases.
Anterior diaphragmatic hernia does not usually interfere with lung development to
any significant extent, and it manifests mainly as an obstruction of the intestines
that resolves after surgery. Associated defects have been found in the heart and
nervous system.
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Inheritance pattern
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The inheritance is most probably multifactorial, i.e. a number of genes act together,
possibly with environmental effects.
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Penetrance
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Unknown.
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Associated features that can be demonstrated in tests performed during pregnancy
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In posterior diaphragmatic hernia associated defects occur in approximately 30%
of cases and include defects in the gastrointestinal tract, neural tube defects,
heart defects etc. As noted, chromosomal problems occur in approximately 4% of cases.
Therefore it is advisable to perform chromosome analysis on amniotic fluid, or on
blood in the case of a neonate, in addition to performing an ultrasound examination that is directed towards
the organs that tend to have defects.
In anterior diaphragmatic hernia, associated defects have been found mainly in the
heart and nervous system.
In all these cases, it is important to refer the couple for genetic counseling, to which they should bring
all data, including the results of other tests performed during the pregnancy such
as alpha-fetoprotein, nuchal translucency, etc.
It is also advisable to refer the parents to a multidisciplinary clinic in a hospital
for professional counseling by a geneticist, an expert in ultrasound examinations,
a pediatric surgeon and a neonatologist, in order to collate all the data and discuss
the various risks in each specific case, the method of monitoring the fetus, possible
intervention if indicated, etc. The decisions taken will depend on the severity
of the problem, the presence of additional findings, etc.
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What is the risk of recurrence in a subsequent pregnancy?
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In posterior diaphragmatic hernia, the risk that a couple who have had a child with
this condition will have another is approximately 2%. Such a couple is also at increased
risk (2%) for having a child with a neural tube defect. The risk of recurrence of
diaphragmatic hernia increases if the parents have affected relatives or if other
defects have been found in addition to the hernia. For more distant relatives, the
risk is determined within genetic counseling based on the cause of the hernia and
the pedigree, the results of tests such as chromosome analysis, etc.
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Molecular genetic information
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The gene for the disease
Not known
Location
Not known
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Genetic testing
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Diagnostic testing
Not available.
Carrier testing
Not available.
Fetal testing
Ultrasound examination only.
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