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Diaphragmatic Hernia



This is a congenital defect of the closure of the diaphragm, which is the muscle that separates the abdominal and chest cavities.

Types

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.

Clinical signs


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.
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.

Inheritance pattern

The inheritance is most probably multifactorial, i.e. a number of genes act together, possibly with environmental effects.

Penetrance

Unknown.

Associated features that can be demonstrated in tests performed during pregnancy

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.

What is the risk of recurrence in a subsequent pregnancy?

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.

Molecular genetic information

The gene for the disease

Not known

Location

Not known

Genetic testing

Diagnostic testing

Not available.

Carrier testing

Not available.

Fetal testing

Ultrasound examination only.
 
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