+++
NEONATAL SURGERY: CONGENITAL DIAPHRAGMATIC HERNIA
++
Failure of complete formation of the diaphragm characterized by pulmonary hypoplasia due to intrauterine compression of the developing lungs by herniated viscera
++
Incidence is 1000 per year (1 in 2000 to 1 in 5000 live births); female:male = 2:1
7–10% gestations end in fetal death
Defects more common on left side (about 80%)
Associated anomalies (10–35%) include central nervous system (CNS) lesions, tracheobronchial abnormalities, omphalocele, cardiovascular (CV) lesions, skeletal malformations and syndromes (trisomy 13, 18, 21, Beckwith–Wiedemann, Brachmann–de Lange, and Pallister–Killian, among others)
++
Unknown currently, though several pharmacologic and environmental factors have been implicated, including a possible role for vitamin A deficiency and/or retinoid-regulated gene defects
Embryologic theory: Lack of closure of the posterolateral pleuroperitoneal canals in the 8th week of gestation fails to separate the thoracic and abdominal cavities.
Portions of the diaphragm and pulmonary parenchyma arise from thoracic mesenchyme; if disrupted, this may lead to absence of part of hemidiaphragm and pulmonary hypoplasia.
Most cases are sporadic; familial cases occur (2%)
+++
Differential Diagnosis
++
Cystic adenomatoid malformation, cystic teratoma, pulmonary sequestration, bronchogenic cyst, neurogenic tumors, primary lung sarcoma, diaphragmatic eventration
++
Herniation of abdominal contents into thoracic cavity through posterolateral foramen of Bochdalek
The diaphragmatic defect may be small or may include entire hemidiaphragm (diaphragmatic agenesis).
The pulmonary vasculature has increased muscularization of pulmonary arterioles and decreased branching of vessels resulting in pulmonary hypertension
The lungs are hypoplastic owing to chronic compression, with decreased numbers of bronchial branches on both the ipsilateral and contralateral sides.
+++
Clinical Manifestations
++
Most patients present with respiratory distress within the first hours of life secondary to severe pulmonary hypoplasia and associated pulmonary hypertension.
10–20% may have a delayed presentation characterized by less severe pulmonary hypoplasia and pulmonary hypertension, as well as gastrointestinal (GI) symptoms (e.g., vomiting, abdominal pain, constipation)
Pneumothorax
On exam: Absence of breath sounds; bowel sounds in chest; scaphoid abdomen; increased anteroposterior diameter of chest; shifted heart sounds
++
Prenatal ultrasound able to detect defect as early as 11th week, mean gestational age at diagnosis is 24 weeks; accuracy has been reported to be between 40 and 90%.
Antenatal diagnosis is associated with more severe defects and a worse prognosis; if diagnosed by ultrasound, fetal magnetic resonance imaging (MRI) should be performed.
During the fetal period, a lung–head ratio (area of contralateral lung to fetal head circumference on ultrasonography) of <1 indicates severe disease.
Observed-to-expected lung–head ratio (O/E LHR) accounts for changes in LHR with gestational age, and O/E LHR <25% suggests severe CDH
Echocardiography and amniocentesis to detect other anomalies
+++
Initial Medical Management
++