What is Diaphragmatic Hernia?
Congenital diaphragmatic hernia (CDH) is an opening in the diaphragm, the muscle under the lungs that is responsible for breathing. Although there are several types of CDH, a Bochdalek hernia in the posterolateral location is the most common and affects about 1 in every 2,500 babies. The defect can occur on either side, but is most common on the left. Rarely, the entire diaphragm is missing on that side. Through this opening, loops of bowel (and sometimes stomach, liver and other organs) protrude into the chest cavity. It is not the opening itself that causes the problem per se; rather the failure of the lung to grow and develop, not only on the same side as the CDH, but to a lesser extent on the other side as well (Figure 1). This condition is termed pulmonary hypoplasia.
CDH can be isolated, or be accompanied by chromosomal abnormalities in up to 30%, congenital heart disease in up to 40%, syndromes, and other structural defects which can all affect survival. CDH is a serious, life-threatening condition with national survival rates approximating 70%.
CDH can be detected by ultrasound as early as 14 to 15 weeks. MRI is commonly used to gain additional detail. An amniocentesis is offered and an echocardiogram obtained to assess heart structure. As the pregnancy progresses, the diagnosis becomes more accurate and stratification into risk groups is attempted based on imaging assessments of pulmonary hypoplasia by both US and MRI.
Prenatal Management
CDH is routinely treated after the baby is born. Fetal intervention has been under investigation for over 20 years and continues to evolve. Attempts to plug or close off the trachea by a detachable balloon in mid-gestation by FETO (Fetal Endoscopic Tracheal Occlusion) may allow the lung to expand by the fluid it produces. In a recent Eurofetus study, severe risk babies were given FETO with encouraging results: the procedure increased survival rates from 10-40% to 40-80%. The utilization of FETO in the most severe risk groups is under investigation by an FDA sponsored trials in select US centers.
With advance knowledge of a fetus with CDH, one can plan the mode, place and time of delivery to ensure that emergent care by specialists is available at the critical time of birth and thereafter (termed the “honeymoon period”).
Many (but not all) physicians recommend a vaginal delivery, unless there are obstetrical reasons to proceed with a C-section. This may be by induction in order to promote a “daytime delivery” vs. scheduled C section to allow more ready access to the care team. The mode of delivery does not appear to have a profound impact on newborn survival.
As long as the fetus is inside the womb, they are supported by the placenta. After birth, however, the baby may be unable to support their breathing and need urgent intervention by placement on a ventilator and specialized therapies such as ECMO (see below). If the diagnosis of CDH has been made beforehand, it is advisable to have the baby born directly in a treatment center (i.e., a center with a neonatal intensive care unit and immediate access to a pediatric surgery service). A term delivery is preferred to allow maximal time for lung development.
What to expect after birth
The infant with CDH is attended to by neonatologists and pediatric surgeons, who will place a breathing tube (intubate) and place the baby on a ventilator. The baby will be monitored in an ICU. An intravenous line and arterial cathether will be inserted, so that fluids and medication can be given and blood sampled. A chest X-ray will be done and an echocardiogram obtained to assess for structural heart disease. Newborns with CDH can develop pulmonary hypertension (pHTN) which makes it difficult for the lungs to extract oxygen from the bloodstream and occasionally lead to heart failure. If the lungs and heart are not able to sustain a safe oxygen level, ECMO (extracorporeal membrane oxygenation) may be utilized. ECMO is a heart and lung bypass system that provides short-term support of the heart and lungs while the baby's condition stabilizes and improves.
When the baby is stable, or on ECMO, the repair of the CDH can be done. The hole in the diaphragm can be closed primarily with sutures if it is small, or may require a patch repair if it is large (Figure 2A, 2B). Returning the abdominal contents from the chest to the abdomen and closing the opening in the diaphragm does not change the size or status of the lungs; therefore this repair will be done if the baby can survive, but is not an emergent surgery.
What happens later
The recovery of the newborn with CDH may take weeks to months to wean off the ventilator and oxygen support. The infant is initially fed through the veins only, but once the gut function returns after surgery, the baby can be fed. This is initially by a feeding tube, and later transitioned to oral feeds as the baby’s lung function stabilizes. Medications can be used to control both reflux, fluid balance, and lung disease.
Developmental support is provided as indicated by the severity of illness. Any associated issues, cardiac or otherwise, are addressed as indicated.
The survival of children with CDH once discharged from the hospital should approach 95-100%. Complications of CDH may include: chronic lung disease requiring oxygen or medications after discharge, gastroesophageal reflux, failure to thrive and growth problems. developmental delays, hearing loss, and recurrence of the CDH due to suture or patch breakdown which typically does not cause symptoms but is repaired.
A child born with CDH will typically need long-term care ideally provided by a multidisciplinary team of pediatric physicians, nurses and other care providers. The complexity of the child’s condition determines the frequency of visits. Long term follow up through young adult years, even if occurring every few years, ensures optimal outcome.
Useful Links
Most Fetal Treatment Centers have useful information online. A list of NAFTNet centers, links and their respective website can be found by clicking here.
Other useful sites, including national organizations, patient- and parent support groups, professional societies and governmental agencies, can be found on our resources page. Be aware that, by clicking on these links, you will leave the NAFTNet site. NAFTNet does not endorse the content of these individual web sites.
Below are a few sites that have specific information on diaphragmatic hernia:
Images of diaphragmatic hernia
Please be aware that some of these images are graphic in nature, and may not be suitable for everyone. Click here to view images.