Congenital diaphragmatic hernia (CDH) is a congenital malformation (birth defect) of the diaphragm. The most common type of CDH is a Bochdalek hernia; other types include Morgagni’s hernia, diaphragm eventration and central tendon defects of the diaphragm. Malformation of the diaphragm allows the abdominal organs to push into the proper lung formation.
CDH is a life-threatening pathology in infants, and a major cause of death due to two complications: pulmonary hypoplasia and pulmonary hypertension. Experts disagree on the relative importance of these two conditions, with some focusing on hypoplasia, others on hypertension. Newborns with CDH often have severe respiratory distress which can be life-threatening unless treated appropriately.
Types of congenital diaphragmatic hernia
The Bochdalek hernia, also known as a postero-lateral diaphragmatic hernia, is the most common manifestation of CDH, accounting for more than 95% of cases. In this instance the diaphragm abnormality is characterized by a hole in the postero-lateral corner of the diaphragm which allows passage of the abdominal viscera into the chest cavity. The majority of Bochdalek hernias (80-85%) occur on the left side of the diaphragm, a large proportion of the remaining cases occur on the right side, and a small fraction are bilateral i.e., left and right sided defects.
This rare anterior defect of the diaphragm is variably referred to as Morgagni’s, retrosternal, or parasternal hernia. Accounting for approximately 2% of all CDH cases, it is characterised by herniation through the foramina of Morgagni which are located immediately adjacent to the xiphoid process of the sternum. The majority of hernias occur on the right side of the body and are generally asymptomatic; However newborns may present with respiratory distress at birth similar to Bochdalek hernia. Additionally, recurrent chest infections and gastrointestinal symptoms have been reported in those with previously undiagnosed Morgagni’s hernia. In asymptomatic individuals laparoscopic surgical repair is still recommended as they are at risk of a strangulated intestine.
The diagnosis of congenital diaphragmatic eventration is used when there is abnormal displacement (i.e. elevation) of part or all of an otherwise intact diaphragm into the chest cavity. This rare type of CDH occurs because in the region of eventration the diaphragm is thinner, allowing the abdominal viscera to protrude upwards. This thinning is thought to occur because of incomplete muscularisation of the diaphragm, and can be found unilaterally or bilaterally. Minor forms of diaphragm eventration are asymptomatic, however in severe cases infants will present with respiratory distress similar to Bochdalek hernia.
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