Morgagni CDH can be mistaken for a number of other thoracic anomalies, both congenital and acquired. In infancy, these can include congenital cystic lung disease, esophageal hiatal hernia, and mediastinal mass.

Later in life, Morgagni hernia can be confused with a mediastinal mass, pericardial fat pad, atelectasis, pneumonia, or a pleural abscess.

The various imaging and diagnostic studies used to distinguish among these are mentioned in a subsequent section.

The diagnosis of a Morgagni diaphragmatic hernia can sometimes be a long and winding road. Neonates do not frequently arrive with the diagnosis already made by prenatal imaging, as is often the case with Bochdalek CDH. The signs and symptoms of Morgagni hernias are also usually nonspecific. Likewise, routine radiologic imaging can also overlook the more subtle defects. Because of this, Morgagni hernias are sometimes not diagnosed until later in life.

The most common presentation in neonates and infants is an increased work of breathing or respiratory distress. Many, however, are relatively asymptomatic. Children may present with a history of recurrent chest infections. Teenagers and adults can present with any variety of symptoms including dyspnea, chest pain, abdominal pain, nausea and vomiting, and constipation or they may be completely asymptomatic. Predisposing conditions, such as chronic cough, trauma, pregnancy, and obesity, can contribute to the likelihood of symptomatic presentation.

The physical examination is most commonly normal. However, distant heart tones and unequal breath sounds may be present. In cases of strangulation or volvulus, the patient may demonstrate significant abdominal tenderness and signs of shock. A detailed physical examination is always indicated in newborns to assess for congenital abnormalities.

Although most commonly isolated, Morgagni hernias can be associated with congenital heart disease, malrotation, and Down’s syndrome.1 The workup should include an echocardiogram when the diagnosis is made in infancy.

Morgagni hernias are not frequently detected on prenatal imaging.

A posteroanterior (PA) and lateral chest radiograph is the initial diagnostic study of choice. This can have different appearances depending on the contents within the hernia. It may show airfilled loops of bowel projecting over the anterior mediastinum (FIG 1A,B) or a well-defined opacity in the right cardiophrenic angle (FIG 2). The latter, however, is not very specific.

The diagnosis can be more readily made on computed tomography or magnetic resonance imaging (MRI) (FIG 3).

Ultrasound, barium enema, and upper gastrointestinal (GI) series also can be a useful part of the diagnostic workup.

Diagnostic thoracoscopy or laparoscopy is recommended if the diagnosis remains unclear after appropriate imaging studies.