A diaphragmatic hernia is an opening or defect in the diaphragm, the dome-shaped muscle separating your chest from your abdomen, that allows abdominal organs to push up into the chest cavity. This can happen before birth due to incomplete development of the diaphragm, or later in life following a traumatic injury. The condition ranges from a life-threatening emergency in newborns to a subtle, sometimes missed finding in adults after a car accident or other blunt force trauma.
How the Diaphragm Normally Works
The diaphragm sits beneath your lungs and above your stomach, liver, and intestines. It contracts and flattens each time you breathe in, creating the negative pressure that pulls air into your lungs. It also acts as a physical barrier, keeping abdominal organs in place. When a gap forms in this muscle, whether from a developmental failure or a tear, organs like the stomach, intestines, or even the spleen can slide upward into the chest. Once there, they compress the lungs and can shift the heart to one side.
Congenital Diaphragmatic Hernia in Newborns
Congenital diaphragmatic hernia (CDH) occurs when the fetal diaphragm doesn’t fully form during pregnancy. The result is a hole that allows abdominal organs to migrate into the chest while the baby is still developing. This happens in roughly 1 in 2,500 to 3,000 live births.
The problem goes beyond organs being in the wrong place. Because the lungs share space with displaced intestines or stomach during critical weeks of development, they don’t grow to full size. This underdevelopment, called pulmonary hypoplasia, means the lungs have fewer air sacs than normal and fewer blood vessels to exchange oxygen. The blood vessels that do form tend to be thicker and stiffer, resisting blood flow. Together, these changes make breathing extremely difficult once the baby is born and can no longer rely on the placenta for oxygen.
There are two main subtypes based on where the hole forms. Bochdalek hernias occur in the back and side of the diaphragm and account for 70 to 75% of all congenital cases. They predominantly appear on the left side. Morgagni hernias form at the front of the diaphragm, just behind the breastbone, and are much less common. Bilateral hernias, affecting both sides, are rare.
Acquired Diaphragmatic Hernia in Adults
In adults, a diaphragmatic hernia almost always results from physical trauma. Blunt force injuries, like those from car crashes or falls, are the most common cause, though penetrating wounds such as stab injuries can also tear the diaphragm. In rarer cases, the hernia develops as a complication of surgery or occurs spontaneously.
Blunt trauma carries a higher risk of serious outcomes compared to penetrating injuries, with mortality rates of about 20% versus 9% in one large analysis. That difference partly reflects the fact that blunt force injuries tend to involve more severe overall damage to the body. One of the trickiest aspects of traumatic diaphragmatic injury is that it can be missed initially. In a major case series of 28 patients with delayed post-traumatic hernias, half eventually presented as surgical emergencies, and the mortality rate was 11%.
Symptoms to Recognize
In newborns, symptoms appear within minutes to hours of birth. The baby struggles to breathe, the skin may turn bluish from lack of oxygen, and the abdomen can look unusually flat or sunken because organs that should be there have shifted into the chest. Heart sounds may be displaced to the opposite side.
In adults, the picture is more variable. Symptoms range from mild chest or upper abdominal discomfort to severe respiratory distress and signs of bowel obstruction if the herniated intestine becomes trapped or twisted. Some people experience repeated vomiting, shortness of breath, or pain that worsens after eating. Because these symptoms overlap with many common conditions, a traumatic diaphragmatic hernia can go undiagnosed for weeks, months, or even years after the original injury.
How It’s Diagnosed
In babies, many cases are detected before birth. Prenatal ultrasound can reveal the stomach or intestinal loops sitting inside the chest cavity, with the heart pushed to the opposite side and compressed, underdeveloped lung tissue. Excess amniotic fluid can also raise suspicion, since it may signal a gastrointestinal abnormality.
After birth or in adults, a chest X-ray is often the first clue. The classic finding is air-filled loops of bowel visible in the chest with reduced gas in the abdomen. CT scans provide a more detailed view, clearly showing which organs have herniated and how they relate to surrounding structures. In congenital cases, imaging typically reveals a visible defect or absence of the diaphragm on the affected side, a shift of the central chest structures, and reduced lung volume.
Surgical Repair
Surgery is the definitive treatment for both congenital and acquired diaphragmatic hernias. The goal is to move the displaced organs back into the abdomen and close the hole in the diaphragm.
Surgeons can approach the repair through the abdomen (laparotomy) or through the chest (thoracotomy or a less invasive camera-assisted technique). For acute traumatic injuries in stable patients, guidelines from the Eastern Association for the Surgery of Trauma recommend the abdominal approach because it allows the surgeon to check for other injuries in the abdomen at the same time. For delayed or chronic hernias discovered long after the original trauma, the choice depends on whether the situation is emergent, how difficult it will be to move organs back into place, and the surgeon’s expertise.
Smaller defects can be stitched closed directly. Larger holes, particularly those seen through a chest approach, may require a synthetic patch made of materials like Gore-Tex or polypropylene mesh to bridge the gap. In one institutional review, about 73% of patients had a direct suture repair while 27% needed a patch. Survival data shows that patients who undergo primary repair without a patch tend to do slightly better, with 90% survival compared to 79% for patch repairs, likely because needing a patch signals a larger, more severe defect rather than a problem with the patch itself.
What Affects Survival in Newborns
CDH survival has improved substantially over the past few decades. One UK surgical center reported an overall survival rate of 85% across its patient population. Several factors have driven this improvement: delivering babies with a known CDH diagnosis at specialized centers, using gentler ventilation strategies that avoid further lung damage, better heart and lung support in the intensive care unit, and delaying surgery until the baby’s condition stabilizes rather than rushing to the operating room.
Babies with additional heart defects face a harder road. In recent cohorts, nearly 70% of CDH patients had associated cardiac malformations, and these infants required more aggressive circulatory support. In the most critical cases, a technology called ECMO (essentially a heart-lung bypass machine) can temporarily take over breathing and circulation while the baby’s lungs recover. Use of ECMO has tripled in recent years as sicker babies are now surviving long enough to reach surgical repair.
The degree of lung underdevelopment remains the single biggest factor in outcomes. Babies with more lung tissue at birth, whose organs herniated later in fetal development or through a smaller defect, generally recover faster and face fewer long-term breathing problems. Those with severe lung underdevelopment may need respiratory support for weeks or months and can have ongoing issues with lung function, feeding, and growth as they get older.