Medicina

Use of this content is subject to the Terms and Conditions of the MD Consult web site. KLIEGMAN: NELSON TEXTBOOK OF PEDIATRICS, 19TH E

DIAPHRAGMATIC HERNIA
Akhil Maheshwari,
Waldemar A. Carlo
A diaphragmatic hernia is defined as a communication between the abdominal and thoracic cavities with or without abdominal contents in the thorax (Fig. 95-10). The etiology may be congenital ortraumatic. The symptoms and prognosis depend on the location of the defect and associated anomalies. The defect may be at the esophageal hiatus (hiatal), paraesophageal (adjacent to the hiatus), retrosternal (Morgagni), or at the posterolateral (Bochdalek) portion of the diaphragm. The term congenital diaphragmatic hernia typically refers to the Bochdalek form. These lesions may cause significantrespiratory distress at birth, can be associated with other congenital anomalies, and have significant mortality and long-term morbidity. The overall survival from the CDH Study Group is 67%. The Bochdalek hernia accounts for up to 90% of the hernias seen in the newborn period, with 80-90% occurring on the left side. The Morgagni hernia accounts for 2-6% of congenital diaphragmatic defects. The size ofthe defect is highly variable, ranging from a small hole to complete agenesis of this area of the diaphragm.
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Congenital Diaphragmatic Hernia (Bochdalek)
Pathology and Etiology
Although CDH is characterized by a structural diaphragmatic defect, a major limiting factor for survival is the associated pulmonary hypoplasia. Lung hypoplasia was initially thought to be due solely tothe compression of the lung from the herniated abdominal contents, which impaired lung growth. However, emerging evidence indicates that pulmonary hypoplasia, at least in some cases, may precede the development of the diaphragmatic defect.
Pulmonary hypoplasia is characterized by a reduction in pulmonary mass and the number of bronchial divisions, respiratory bronchioles, and alveoli. Thepathology of pulmonary hypoplasia and CDH includes abnormal septa in the terminal saccules, thickened alveoli, and thickened pulmonary arterioles. Biochemical abnormalities include relative surfactant deficiencies, increased glycogen in the alveoli, and decreased levels of phosphatidylcholine, total DNA, and total lung protein, all of which contribute to limited gas exchange.
Epidemiology
Theincidence of CDH is between 1/2,000 and 1/5,000 live births, with females affected twice as often as males. Defects are more common on the left (85%) and are occasionally (<5%) bilateral. Pulmonary hypoplasia and malrotation of the intestine are part of the lesion, not associated anomalies. Most cases of CDH are sporadic, but familial cases have been reported. In one study, complete agenesis of thediaphragm had an autosomal recessive pattern of inheritance; in the majority of cases, genetic factors are multifactorial. Associated anomalies have been reported in up to 30% of cases; these include CNS lesions, esophageal atresia, omphalocele, and cardiovascular lesions. CDH is recognized as part of several chromosomal syndromes: trisomy 21, trisomy 13, trisomy 18, Fryns, Brachmann-de Lange,Pallister-Killian, and Turner.
Diagnosis and Clinical Presentation
CDH can be diagnosed on prenatal ultrasonography (between 16 and 24 wk of gestation) in > 50% of cases. High-speed fetal MRI can further define the lesion. Findings on ultrasonography may include polyhydramnios, chest mass, mediastinal shift, gastric bubble or a liver in the thoracic cavity, and fetal hydrops. Certain imagingfeatures may predict outcome; these include lung to head size ratio (LHR). Nonetheless, no definitive characteristic reliably predicts outcome. After delivery, a chest radiograph is needed to confirm the diagnosis (Fig. 95-11). In some infants with an echogenic chest mass, further imaging is required. The differential diagnosis may include a cystic lung lesion (pulmonary sequestration, cystic...