Congenital Diaphragmatic Hernia - Types, Causes, Symptoms, Diagnosis, and Treatment

Introduction:

Congenital diaphragmatic hernia (CDH) is a developmental abnormality that causes protrusion of the abdominal contents into the thoracic cavity. The diaphragm is a thin muscular sheet separating the chest from the abdomen. In a congenital diaphragmatic hernia, a hole is created in the diaphragm muscle layer, resulting in an abnormal opening through which the abdominal contents protrude into the thorax. During the development of the fetus in the uterus, the diaphragm muscle fails to close. Therefore, it results in the migration of the stomach, intestines, and liver into the chest. This abnormal migration affects lung development resulting in several lung complications such as pulmonary hypoplasia (underdevelopment of the lungs) and pulmonary hypertension.

What Are the Types of Congenital Diaphragmatic Hernia?

Depending on the location of the defect, the congenital diaphragmatic hernia is classified into four variants such as:

• Bochdalek Hernia: It is the most common type and is seen in 70% to 75% of cases. It affects the posterolateral part of the diaphragm.

• Morgagni Hernia: It is seen in 20% to 25% of the cases. It affects the anteromedial portion of the diaphragm.

• Central Hernia: It affects two to five percent of the total cases.

• Bilateral Hernia: It is a very rarely occurring variant.

What Is the Incidence of Congenital Diaphragmatic Hernia?

• It is a common birth disorder affecting one in 2500 to 3000 live births.

• The congenital diaphragmatic hernia has a male predilection, and the reason for this is still unknown.

What Is the Cause of Congenital Diaphragmatic Hernia?

Although the exact cause of congenital diaphragmatic hernia is uncertain, it is believed to be multifactorial. It includes genetic, environmental, and nutritional factors. The genetic conditions contributing to this disorder are any mutations seen in GATA4 and LRP2 genes. Congenital diaphragmatic hernia is also seen in Trisomy 18, Trisomy 13, Trisomy 21, and Turner syndrome. Other factors that may cause congenital diaphragmatic hernia are:

• Exposure to teratogens such as Mycophenolate mofetil, Allopurinol, lithium, etc., during pregnancy, especially during the first trimester when organogenesis takes place.

• Any disturbances to the retinoid signaling cells may also cause this congenital disability.

What Are the Other Syndromes Associated With Congenital Diaphragmatic Hernia?

• Pallister-Killian syndrome.

• Fryns syndrome.

• Cornelia de Lange syndrome.

What Is An Isolated Congenital Diaphragmatic Hernia?

In some cases, a congenital diaphragmatic hernia occurs without any genetic cause. Therefore, it is referred to as an isolated congenital diaphragmatic hernia.

What Is Pathophysiology?

The diaphragm is a thin layer of muscle that separates the chest from the abdomen. The septum transversum and the pleuroperitoneal membrane form the major component of the diaphragm. Generally, the development of the diaphragm muscle is completed by the 12th week of gestation. Any disturbances during this period may result in discontinuity or failure of muscle closure, resulting in abnormal communication. In addition, it results in the protrusion of the abdominal contents into the thorax, thus interfering with lung development. In CDH, the left lung is usually more affected than the right lung.

What Is the Clinical Presentation of CDH?

• Chronic lung disease.

• Hearing loss.

• Recurrence of hernia.

• Pulmonary Hypertension: It occurs due to the underdevelopment of the pulmonary blood vessels and the inability to take up enough oxygen from the lungs.

• Gastroesophageal Reflux: A condition where fluids and acids from the stomach move up into the esophagus resulting in heart burns, vomiting, etc.

• Failure to Thrive: Lung problems may interfere with the growth and nutrition of the child. Hence feeding is supported with the help of feeding tubes.

• Developmental Delays: The child may take longer than usual to reach the milestones compared to the other children.

What Is the Difference Between Left CHD and Right CDH?

The left congenital diaphragmatic hernia is seen in almost 83 % of cases. It results in the migration of the stomach, intestines, and liver into the chest cavity of the baby. The right-sided congenital diaphragmatic hernia is seen in 17 % of the cases where the liver is moved up into the chest cavity.

What Are the Other Similar Conditions?

• Congenital cystic adenomatoid malformations.

• Bronchopulmonary sequestration.

• Bronchogenic cysts.

• Bronchial atresia.

• Teratomas.

How Is Congenital Diaphragmatic Hernia Diagnosed?

More than half of congenital diaphragmatic hernia cases are diagnosed during prenatal ultrasounds. The prenatal ultrasounds performed during the 18th to 24th weeks may show the abdominal contents in the fetal chest cavity. It also indicates the presence of excess amniotic fluid.

The diagnostic procedures performed are:

• Doppler Ultrasound: The test is performed to identify the presence of ductus venosus and intrahepatic vessels in the thoracic cavity.

• Fetal Echocardiogram: It evaluates the structure and the functioning of the heart of the baby.

• Fetal Magnetic Resonance Imaging Test (MRI): This imaging test analyzes the chest and assesses lung development. It helps to predict the severity of CDH in the baby.

• Amniocentesis and Chorionic Villi Sampling: The amniotic fluid and a portion of the placental cells are taken and examined. It reveals the presence of any abnormalities in the baby from the genetic material in the amniotic fluid.

• Chest X-Ray: They are taken soon after the baby is born. The X-ray imaging of the chest reveals the abnormalities of the lungs, diaphragm, and intestines if present.

• Arterial Blood Gas Test: The arterial blood gas test is done on the baby to evaluate breathing ability.

How to Determine the Severity of CDH?

The severity of the condition is often predicted depending on the location of the liver in the baby. If the liver is situated in the chest region, it may obstruct and retard the growth of the lungs resulting in pulmonary hypoplasia. Pulmonary hypoplasia is calculated by measuring the following:

• Lung area to the circumference of the head.

• Total lung volume.

How Is CDH Treated?

After the diagnosis and confirmation of the condition, the treatment plan is done according to the severity. The treatment is categorized into:

Antenatal Management: If the doctor confirms the diagnosis of a congenital diaphragmatic hernia in the baby, close monitoring is done to assess the growth. In cases of severe CDH, fetal therapy is done.

Fetal Therapy: The trachea of the fetus is occluded with the assistance of an inflated balloon. This procedure is done under endoscopic visualization around 26 to 30 weeks of gestation. This procedure results in fluid accumulation in the lungs, stretching the organ and allowing it to grow adequately. The balloon is then retrieved between 33 to 34 weeks, which may affect the surfactant production. Although fetal therapy has a risk for preterm delivery, it is performed with utmost care and precautions as it may increase the survival rate of the baby.

Postnatal Management: Generally, in babies with CDH, labor is not attempted or encouraged before the completion of 37 weeks. It is always better to wait until 39 weeks unless there is an emergency for delivery. Soon after birth, the placement of a nasogastric tube is recommended to decompress the stomach and intestines.

• In case of respiratory distress, bag-mask ventilation should be avoided, and intubation should be started immediately.

• If pulmonary hypertension is suspected, inhaled nitric oxide is given in infants older than 34 weeks of gestation.

• If the child does not respond to any conservative treatments, the final option is extracorporeal membrane oxygenation (ECMO). It is initiated following the guidelines given by the CDH Euro consortium.

• The ECMO takes over the function of the lungs, delivers oxygen, and removes carbon dioxide.

• Surgery is usually done only after 48 to 72 hours after birth. This time is given for the adaptation of pulmonary vasculature. The surgical repair of the defect is performed under general anesthesia and monitored continuously. An incision is made below the ribcage, and the organs are placed in the abdomen and secured with the suture.

• A muscle flap or Gore-Tex patch is used to close the opening if the hole is extremely large. It is then assessed regularly as the child grows and checked for intactness.

What Are the Post-operative Instructions?

• The baby will require regular follow-ups.

• Nutrition is essential for the proper growth of the lungs. Initially, food is supplied through an intravenous route. Then, soon after recovery from surgery, a nasogastric feeding tube is placed that goes directly into the stomach and intestines.

Conclusion:

The diagnosis of congenital diaphragmatic hernia in the child may be distressing for the parents. These patients may require long-term periodic follow-ups. Parents are counseled and explained the importance of regular follow-up for the betterment of the health of the child.