A diaphragmatic hernia is a hole in the diaphragm, the large dome-shaped muscle that separates your chest from your abdomen, that allows abdominal organs like the stomach, intestines, or liver to push upward into the chest cavity. This condition can be present at birth or develop later in life from trauma or injury. While it shares a name with the more common hiatal hernia, a diaphragmatic hernia is a distinct and often more serious condition that can compress the lungs and heart.
How It Differs From a Hiatal Hernia
People often confuse diaphragmatic hernias with hiatal hernias because both involve the diaphragm. A hiatal hernia is a specific, usually mild condition where the upper part of the stomach slides through the natural opening (the hiatus) where the esophagus passes through the diaphragm. It’s extremely common, especially in people over 50, and its main symptom is acid reflux.
A diaphragmatic hernia involves an abnormal hole in the diaphragm itself, separate from that esophageal opening. Multiple organs can push through, not just the top of the stomach. The consequences tend to be far more serious because herniated organs can crowd the heart and lungs, interfering with breathing and circulation.
Congenital Diaphragmatic Hernia
The most well-known form is congenital diaphragmatic hernia (CDH), a birth defect where the diaphragm doesn’t fully form during fetal development. CDH occurs in roughly 2.3 to 2.8 out of every 10,000 births worldwide. It’s rare but carries significant risk: mortality rates range from 30% to 60%, and can reach as high as 89% when the baby also has chromosomal or other structural abnormalities.
CDH comes in two main types based on where the hole forms. The most common is a Bochdalek hernia, located toward the back and side of the diaphragm. The less common Morgagni hernia occurs at the front, near the breastbone. Left-sided hernias are more frequent than right-sided ones, likely because the liver provides some structural reinforcement on the right.
Why It Affects Lung Development
The real danger of CDH isn’t just the misplaced organs. When abdominal organs occupy space in the chest during fetal development, they physically prevent the lungs from growing to full size. This results in lungs that are smaller than expected, with underdeveloped blood vessels. The combination creates high blood pressure in the lungs (pulmonary hypertension), making it extremely difficult for the newborn to breathe and get adequate oxygen after birth.
The severity depends largely on how much lung growth was disrupted. One of the strongest predictors is whether the liver has herniated up into the chest. When it has, the lungs tend to be significantly smaller. Doctors use fetal ultrasound and MRI measurements, including the ratio of lung area to head circumference, to estimate how much lung tissue has developed before the baby is born.
Symptoms in Newborns
Babies born with CDH typically show signs immediately. Severe breathing difficulty is the hallmark symptom, caused by lungs that are too small and stiff to function properly. Pulmonary hypertension compounds the problem by forcing the heart to work harder. Some babies also have heart development issues or damage to abdominal organs that shifted into the chest.
Acquired Diaphragmatic Hernia
A diaphragmatic hernia can also develop after birth, though this is uncommon. Fewer than 1% of people who experience trauma sustain a diaphragmatic injury. Most cases occur in people in their 30s.
Motor vehicle accidents are the leading cause when blunt force is involved. Gunshot or stab wounds account for most penetrating injuries to the diaphragm. In rare cases, the diaphragm can rupture during childbirth in women who previously had hernia repair, or following organ transplant surgery. Like congenital cases, acquired hernias occur more often on the left side (about 69% of cases) than the right (about 24%), because the liver helps protect and reinforce the right side of the diaphragm.
How It’s Diagnosed
For congenital cases, diagnosis usually happens before birth during a routine prenatal ultrasound. The scan can reveal abdominal organs sitting in the chest cavity and a heart that has been pushed to one side. Ultrasound does have limitations, though. Fetal lung tissue and herniated organs can look similar on the screen, and image quality depends on factors like maternal body composition and the technician’s experience.
When ultrasound findings are unclear, prenatal MRI provides a more detailed picture. It can distinguish the fluid-filled stomach, looping bowel, and liver tissue from lung tissue based on differences in signal intensity. MRI is particularly useful for right-sided hernias, where the main herniated organ is the liver, which can be harder to differentiate from lung on ultrasound. It also helps doctors measure remaining lung volume to plan for the level of care the baby will need at delivery.
In adults with acquired hernias, a chest X-ray may show bowel loops or other abdominal contents above the diaphragm. CT scans provide the most detailed view and are the standard imaging tool after trauma.
Surgical Repair
Surgery is the definitive treatment for diaphragmatic hernias. The goal is to move the displaced organs back into the abdomen and close the hole in the diaphragm. For newborns with CDH, this typically happens after the baby has been stabilized, sometimes requiring days or weeks of intensive respiratory support first.
Surgeons can approach the repair in several ways. Open surgery involves a larger incision and direct access to the defect. Laparoscopic surgery uses several small incisions and specialized instruments, which generally means less tissue disruption and a shorter recovery. Robotic-assisted surgery works similarly to laparoscopic repair but gives the surgeon enhanced precision through motion scaling and tremor reduction.
Small defects can sometimes be closed with stitches alone. Larger holes often require a patch, either made from synthetic material or processed animal tissue (typically from pig or cow sources). Synthetic patches can be absorbable, dissolving over time as the body’s own tissue fills in, or permanent, staying in place indefinitely to reinforce the repair. Studies consistently show that using mesh reduces the chance of the hernia coming back, though mesh carries its own risks including potential migration or shrinkage over time.
Long-Term Outlook
For children who survive CDH repair, the average survival probability at age five and beyond ranges from 64% to 77%. Those who make it through infancy face ongoing considerations, but the outlook is generally manageable.
Recurrence of the diaphragmatic defect is surprisingly common, showing up in about 43% of people who had standard repair and up to 77% of those who required the most intensive life support as newborns. The reassuring finding is that most recurrences cause no symptoms. In one long-term study, only 2 out of 38 people with recurrent hernias needed a second surgery. The rest remained symptom-free.
Lung function does tend to remain below normal into adulthood for CDH survivors. Imaging studies show mild to moderate structural changes in the lungs, and exercise capacity is reduced, with peak oxygen consumption measuring around 73% to 88% of predicted normal values depending on how intensive their initial treatment was. However, resting heart evaluations in these same adults showed no signs of the pulmonary hypertension that threatened them at birth. Most CDH survivors lead active lives, even if their exercise tolerance is somewhat lower than average.