A Bochdalek hernia is a type of congenital diaphragmatic hernia (CDH), a birth defect involving a hole in the diaphragm, the muscle separating the chest and abdominal cavities. This opening allows abdominal organs, such as the stomach, intestines, spleen, or liver, to move into the chest cavity. It is a rare, life-threatening condition primarily diagnosed and treated in newborns. The condition is considered a medical emergency due to the immediate strain it places on the newborn’s ability to breathe.
Understanding the Condition and Its Origin
The condition arises from a failure during fetal development, specifically concerning the diaphragm’s formation between the eighth and tenth week of gestation. The diaphragm develops from several components, including the pleuroperitoneal folds, which must fuse to seal the chest from the abdomen. In a Bochdalek hernia, the posterolateral portion of the diaphragm, known as the foramen of Bochdalek, fails to close completely.
This defect is found on the left side of the body in about 85% of cases. The liver, which develops on the right side, is thought to help facilitate the closure of the right pleuroperitoneal fold. The presence of abdominal organs in the chest cavity severely limits the space available for the developing lungs. This compression results in pulmonary hypoplasia, the underdevelopment of the lungs’ structure.
The lungs of a newborn with this condition have fewer air sacs (alveoli) and blood vessels than normal, severely compromising gas exchange. Furthermore, the defect causes persistent pulmonary hypertension of the newborn (PPHN). PPHN is a condition where the blood vessels in the lungs remain constricted, preventing proper blood flow. This drastically worsens the newborn’s ability to oxygenate their blood.
Identifying Bochdalek Hernia
The hernia can be detected before or immediately following birth, with prenatal diagnosis common through routine screening. Fetal anatomy scans using ultrasound can visualize the defect, often revealing abdominal contents within the chest cavity. A key sign is the displacement of the heart, known as a mediastinal shift, caused by the mass of herniated organs.
The Lung-to-Head Ratio (LHR) is a standard tool for predicting the outcome before birth. LHR compares the size of the developing lung contralateral to the defect with the head circumference. The observed-to-expected LHR (o/e LHR) is a refined measurement that normalizes the ratio to the expected value for the fetus’s gestational age. A lower o/e LHR suggests a smaller, underdeveloped lung, which helps medical teams stratify risk and plan postnatal care.
If the condition is not diagnosed prenatally, newborns present with severe symptoms immediately after birth. These signs include profound respiratory distress, rapid breathing (tachypnea), and a bluish tint to the skin (cyanosis) due to lack of oxygen. The abdomen may appear unusually sunken or “scaphoid” because the abdominal organs have moved into the chest. Diagnosis is quickly confirmed with a chest X-ray, which shows abdominal organs occupying the space where the lung should be.
Treatment Pathway and Long-Term Outlook
Treatment begins with immediate postnatal stabilization, focusing on supporting the newborn’s compromised respiratory and circulatory systems. Intubation and gentle mechanical ventilation are necessary to deliver oxygen without damaging the fragile, underdeveloped lungs. Bag-mask ventilation is avoided, as it can push air into the stomach and intestines, rapidly expanding the herniated organs and further compressing the lungs.
For newborns with severe pulmonary hypoplasia and persistent pulmonary hypertension, supportive therapy may involve Extracorporeal Membrane Oxygenation (ECMO). ECMO is a temporary life support system that takes over the function of the heart and lungs. This allows the newborn’s lungs to rest and recover. The goal is to stabilize the baby and allow lung function to improve before surgical repair.
The definitive treatment is surgical repair, which is delayed until the newborn is physiologically stable, often after several days or weeks. The surgeon gently repositions the herniated organs back into the abdominal cavity and then closes the defect in the diaphragm. If the opening is large, a synthetic patch may be required to bridge the gap and complete the repair.
The long-term outlook is determined by the severity of the pulmonary hypoplasia and pulmonary hypertension. While survival rates have improved with advances in neonatal care, long-term follow-up is necessary for survivors. Potential long-term issues include chronic lung disease, gastroesophageal reflux disease (GERD) due to the repositioning of the stomach, and neurodevelopmental impairment.