Congenital Diaphragmatic Hernia
Congenital diaphragmatic hernia (CDH) is a congenital condition present at birth. The defect involves a malformation of the diaphragm, which allows abdominal organs such as the stomach, liver, spleen and intestines to protrude through a hole into the chest wall. In some cases, the defect causes the lungs to be compressed, which can result in pulmonary hypoplasia or decreased lung development. The defect can be on the right or the left side, but is more commonly found on the left.
CDH occurs in one out of every 2,500 live births. Some cases are part of a chromosomal disorder, although more than half of the incidences are isolated events. The severity of the defect is determined by the position of the liver, either in the abdomen or in the chest, and the lung-to-head ratio (LHR), with ratios over 1 having a more favorable prognosis. MRI determination of lung volumes may also help to predict outcomes.
There are several diagnostic tests available to prenatally diagnose CDH. A prenatal ultrasound is done at the initial visit to help assess the defect, indicate fetal gestational age, measure the growth of the fetus, determine liver position and measure the fetal lung-to-head ratio (LHR). The prognostic value of the LHR is most accurate at 24 weeks gestation. Other associated congenital anomalies may also be detected.
Around 24 weeks' gestation, ultrafast MRI is also obtained to determine position of the liver, assess lung volumes and to look for other associated anomalies.
Fetal echocardiogram should also be performed as soon as diagnosis is identified. CDH can be associated with congenital heart disease, and the prognosis can be dramatically affected by the presence of congenital heart disease depending on the lesion. Fetal chromosomal studies should also be done at the time of diagnosis because of the increased incidence of chromosomal abnormalities with CDH. This is done by analyzing amniotic fluid from around the fetus.
After delivery, infants will often present with a scaphoid abdomen because the abdominal contents are pushed into the thorax. These infants may have respiratory distress and pulmonary hypertension, which is elevated blood pressure in the arteries found in the lungs. This condition is usually related to pulmonary hypoplasia.
Postnatal treatment includes stabilization of the infant after delivery to ensure adequate ventilation. A breathing tube is inserted in the airway to help the infant breath. There are several strategies to decrease pulmonary hypertension and improve the baby's breathing, including the use of supplemental oxygen, nitric oxide and positive pressure ventilation. If pulmonary hypertension is severe and the baby can't get appropriate oxygen into the bloodstream, extracorporeal membrane oxygenation (ECMO) may be used to allow adequate oxygenation while allowing the lungs to rest.
Once the infant is stabilized from a cardiovascular and respiratory standpoint, the diaphragmatic defect is surgically repaired in the intensive care unit, and may require use of a Gore-Tex patch. Potential patch complications include infection, patch separation and reherniation throughout childhood.
Difficulties maintaining sufficient nutrition support during the early critically ill period often require parenteral nutrition. Use for a prolonged period of time carries the risk of cholestasis and hepatic failure.
Once the infant is medically and surgically stable, attempts are made to initiate oral feedings. This often requires initial use of a feeding tube, and some cases may need surgical placement of a gastric tube to achieve adequate nutritional support. Because of the chronic noxious stimuli to the infant's oral cavity, these children have oral aversion that many times makes establishing oral feeding a difficult and challenging process. Almost all children have significant clinical reflux disease requiring aggressive medical management, and some may need surgical fundaoplication because of failed medical management.
Hospitalization can range from six weeks to six months. Some infants are not able to be completely weaned from respiratory support and are sent home with a tracheostomy and outpatient ventilatory support. Long-term effects can include reactive airway disease and bronchial dysplasia, hypotonia, failure to thrive and varying degrees of developmental delays and/or cognitive deficiencies.