Diaphragmatic Hernia - Types, Symptoms, Diagnosis, and Management

Introduction

A diaphragmatic hernia is a congenital defect with an abnormal opening in the diaphragm. It is primarily congenital but can be acquired as well. An acquired diaphragmatic hernia occurs due to trauma from blunt or penetrating injury, spontaneous or due to iatrogenic causes. Acquired diaphragmatic hernia is rare and can be life-threatening, resulting in incarceration and strangulation.

The diaphragm is a muscle that separates the thoracic and abdominal cavities. An opening in the diaphragm allows abdominal organs to move into the thorax. It mainly involves one side of the diaphragm, usually the left side. As a result, the lung on the affected side and the blood vessels are underdeveloped, known as pulmonary hypoplasia, causing high blood pressure in the lungs, known as pulmonary hypertension.

What Is the Pathophysiology Behind Diaphragmatic Hernia?

Acquired diaphragmatic hernia, as a result of trauma, is more likely to occur at areas of potential weaknesses along the embryological points of fusion of the diaphragm. It is produced by a sudden increase in the pleuroperitoneal pressure gradient developed due to trauma. The diaphragmatic hernia tends to occur on the left side of the diaphragm. This is because the liver protects the right side hemidiaphragm.

What Are the Types of Diaphragmatic Hernia?

There are two most common types of diaphragmatic hernia:

• Bochdalek hernia.

• Morgagni hernia.

Bochdalek Hernia:

It involves the sides and back of the diaphragm. The stomach, liver, spleen, or intestines move into the chest cavity. It accounts for 80-85 % of congenital diaphragmatic hernias.

Morgagni Hernia:

It involves the front of the diaphragm. The liver or intestines move into the chest cavity. It accounts for approximately 2 % of congenital diaphragmatic hernias. It is characterized by herniation through Morgagni's foramina, which is immediately adjacent and posterior to the xiphoid process of the sternum.

The diaphragm forms between the fourth to 12th week of intrauterine life. And the esophagus, as well as the intestines, develop at the same time.

What Are the Signs and Symptoms of Diaphragmatic Hernia?

It may produce respiratory, abdominal, and cardiac features. The most common signs and symptoms include:

• Shortness of breath (dyspnea).

• Marked respiratory distress.

• Chest pain.

• Diffuse abdominal pain.

• Postprandial fullness.

• Obstructive gastrointestinal symptoms.

• Vomiting.

• Tachypnea (increased respiratory rate).

• Tachycardia (increased pulse rate).

• Cyanosis (bluish discoloration of the skin).

What Are the Diagnostic Tests That Can Be Carried Out?

The diagnosis can be made with the help of the following:

• Fetal Ultrasound.

• Fetal magnetic resonance imaging.

• Chest X-ray.

Infant Examination:

• Irregular chest movement.

• Absent or decreased breath sounds on the affected side.

• Auscultation of bowel sounds in the chest.

• Paradoxical movement of the abdomen with breathing.

• The lower abdominal protuberance of the infant is compared to a normal infant.

A plain chest radiograph may show an indistinct diaphragm with opacification of part or all of the hemithorax, with the scaphoid abdomen, and deviation of lines such as a nasogastric tube, endotracheal tube, and umbilical arterial and venous catheters. Prenatal diagnosis may allow for chromosomal analysis and screening for other anomalies before the child's birth. Using ultrasonography, a congenital diaphragmatic hernia can be prenatally diagnosed as early as the second trimester of pregnancy.

On fetal ultrasound examination, visualizing abdominal contents in the thoracic cavity and mediastinal shift to the contralateral side of the diaphragmatic defect is a characteristic feature of diaphragmatic hernia. However, if the defect is small and there is an absence of herniation of abdominal contents, it may go unnoticed. A right-sided diaphragmatic hernia is difficult to diagnose since the echogenicity of both lungs and liver is similar on ultrasound.

In this case, a color Doppler ultrasound examination helps identify the presence of ductus venosus and intrahepatic vessels in the thoracic cavity. The lung area-to-head ratio is a marker of the degree of lung volume. It is calculated by measuring the lung area of the contralateral lung divided by the fetal head circumference. Fetal magnetic resonance imaging is a more promising technique that allows precise lung volume measurements indexed to body volume.

What Are the Differential Diagnosis of Diaphragmatic Hernia?

The differential diagnosis includes:

• Congenital cystic adenomatoid malformations.

• Bronchopulmonary sequestration.

• Bronchogenic cyst.

• Bronchial atresia.

• Teratomas.

How Is Diaphragmatic Hernia Managed?

The diaphragmatic hernia can be repaired with the help of surgery. The procedure involves an open abdominal approach and repair by primary closure with non-resorbable sutures. In cases where sutures cannot be placed because of the size of the defect, a mesh can be identified. If the treatment is delayed, a thoracic approach is used to reduce the viscera-pleural adhesions and intra-thoracic visceral herniation.

Even in some delayed cases, a thoracoabdominal approach may be advised. Minimally invasive surgery has become increasingly popular and a mainstay in managing patients with diaphragmatic hernia. It reduces postoperative pain and avoids complications associated with thoracotomy and laparotomy.

Carbon dioxide insufflation during these procedures may cause hypercapnia and acidosis. In addition to the surgical repair, a child with a congenital diaphragmatic hernia may require specialized equipment such as an oscillator ventilator, a heart-lung machine (ECMO), or nitric oxide. The extracorporeal membrane oxygenation allows the lung to rest. At the same time, the device does the work of the heart and lungs, delivering oxygen to the body tissues and removing carbon dioxide from the tissues.

What Are the Complications?

The complications include:

• Diaphragmatic rupture.

• Acute obstructive symptoms.

• Respiratory failure incarceration

• Strangulation.

• Cardiac tamponade.

• Pulmonary hypoplasia.

• Pulmonary hypertension.

What Are the Prognostic Factors of Diaphragmatic Hernia?

Signs suggestive of poor prognosis include:

• Large hernia size.

• Early gestational age.

• Intrathoracic liver.

• Small contralateral lung.

• Pulmonary hypertension.

• Early ventricular dysfunction, specifically biventricular dysfunction.

• Presence of associated abnormalities.

• Unfavorable lung head ratio.

• Bilateral congenital diaphragmatic hernia.

A composite prognostic index involving ten prenatal parameters was developed and found to have a stronger association with survival and the need for ECMO than any other parameter individually.

Conclusion

A congenital diaphragmatic hernia is a congenital defect with a very high mortality rate. Usually associated with pulmonary hypoplasia and pulmonary hypertension. Diagnosis of congenital diaphragmatic hernia can be challenging as the clinical features are non-specific, and the radiographic features potentially mimic other conditions such as pneumonia, pleural effusion, and pneumothorax. An incorrect diagnosis may expose the patient to unnecessary or harmful interventions.