Congenital diaphragmatic hernia is an abnormality present from birth and is characterized by protrusion of abdominal organs into the thorax due to incomplete development of the diaphragm. As a result, the lungs of neonates are under significant pressure and pulmonary hypoplasia with hypertension are some of the most important complications that put the patient at risk soon after birth. Because both respiratory and gastrointestinal distress can occur, an early diagnosis is pivotal. A physical examination coupled with ultrasonography (either antenatal or postnatal) are the critical components of the workup.
The features of a congenital diaphragmatic hernia arise due to compression of the respiratory system by the protruding abdominal organs into the thorax   . Although the exact pathogenesis model remains to be elucidated, it is suspected that incomplete muscularization of the diaphragm promotes the formation of hernias, and approximately half of all neonates have isolated congenital diaphragmatic hernia without additional genetic malformations . The compressive effects of abdominal contents on the lungs eventually lead to pulmonary hypoplasia and the development of pulmonary hypertension   . These pathological events predispose neonates to respiratory (but also gastrointestinal) distress, which can be life-threatening in the absence of an early diagnosis    . Typical signs include displacement of heart sounds to the contralateral side, protrusion of the sternum with a characteristic "scaphoid abdomen" (as the organs move into the chest), abdominal pain due to intestinal obstruction, and either absence or markedly reduced respiratory bruits   . The most common clinical presentation, however, is severe respiratory insufficiency, often confirmed by low Apgar scores  . Some individuals may be asymptomatic in the neonatal period and develop bouts of respiratory distress in later life, whereas congenital diaphragmatic hernia can be incidentally diagnosed as well .
The diagnosis of a congenital diaphragmatic hernia must be made as soon as possible. Postnatal signs of respiratory distress, low Apgar scores, diminished heart sounds, and the typical appearance of the abdomen are findings that must raise suspicion towards congenital diaphragmatic hernia. Thus, the physician plays a crucial role when performing a physical examination after birth. Arterial blood gas (ABG) analysis and pH levels are needed to assess the extent of impaired oxygenation . To confirm the diagnosis, imaging modalities must be used. Ultrasonography has become the gold standard for detecting diaphragmatic and several other anomalies and should be performed whenever sufficient evidence is gathered    . More importantly, antenatal ultrasonography, which is readily used throughout pregnancy, has shown to be quite successful in recognizing this congenital anomaly as early as 24 weeks of gestation   . Herniation of the intestines and/or the liver into the thorax, a displaced gall bladder, smaller lungs, and polyhydramnios are prominent findings . Additional imaging studies that can be used are plain radiography of the chest and abdomen, as well as fetal magnetic resonance imaging (MRI), which is highly useful if ultrasonography results are inconclusive   .