A Bochdalek hernia is a birth defect in which a hole in the back of the diaphragm allows abdominal organs to push up into the chest cavity, crowding the developing lungs. It is the most common type of congenital diaphragmatic hernia, caused by the failure of a membrane in the diaphragm to close fully during fetal development.1PubMed Central. Bochdalek Hernia in an Adult Causing Intraoperative Complication Most cases are diagnosed before or shortly after birth, but a surprising number go undetected for decades, sometimes turning up as incidental findings on imaging done for completely unrelated reasons.
How the Defect Forms Before Birth
During normal fetal development, the diaphragm forms from several tissue sources that fuse together between roughly the eighth and tenth weeks of gestation. One critical step involves the closure of the pleuroperitoneal membranes, which seal the gap between the chest and abdominal cavities on each side. When one of these membranes fails to close completely, a gap persists at the back of the diaphragm. Abdominal organs, such as loops of bowel, the stomach, the spleen, or even part of the liver, can then migrate upward through this gap into the chest.2Austin Journal of Radiology. Fortuitous Discovery of a Bochdalek Hernia in an Adult
The consequences depend heavily on timing and size. A large defect that allows organs into the chest early in pregnancy means the lungs grow in a cramped space during a critical window. This leads to underdeveloped lungs, a condition called pulmonary hypoplasia, along with abnormal blood vessels in the lungs that are thicker-walled and more reactive than normal. The combination of small lungs and abnormal pulmonary blood vessels drives persistent pulmonary hypertension, which is the main life-threatening complication in affected newborns.3PubMed. Congenital diaphragmatic hernia-associated pulmonary hypertension The vascular abnormalities begin developing while the lungs are still very immature, with excessive muscularization visible even in the smallest capillaries.4European Respiratory Review. Pulmonary vascular development in congenital diaphragmatic hernia
Why Most Bochdalek Hernias Appear on the Left
Between 80 and 90 percent of Bochdalek hernias occur on the left side. Two anatomical reasons explain the imbalance. First, the right pleuroperitoneal canal closes slightly earlier during fetal development, giving it a narrower window during which things can go wrong. Second, even if the right side does have a small defect, the liver sits directly beneath the right half of the diaphragm and effectively plugs the hole, preventing bowel and other organs from migrating upward.5PubMed Central. Right-sided Bochdalek hernia in an adult: a case report Right-sided hernias do occur, though, and they can be particularly challenging to manage surgically because the liver itself may herniate into the chest.
There is also a distinction worth knowing between Bochdalek and Morgagni hernias, the two named types of congenital diaphragmatic hernia. A Bochdalek hernia is a defect at the back and side of the diaphragm, while a Morgagni hernia sits at the front. Bochdalek hernias are far more common and tend to be larger and more clinically significant at birth.6Journal of Surgical Case Reports. Morgagni hernia: an uncommon pathology in adults
Genetic Factors and Sporadic Cases
Most Bochdalek hernias arise sporadically, meaning they occur without a clear inherited cause. Still, researchers have identified a range of genetic factors that contribute to a proportion of cases, from extra or missing chromosomes to smaller deletions and mutations in individual genes.7European Journal of Human Genetics. Genetics of diaphragmatic hernia The full list includes chromosomal abnormalities such as trisomy 13, deletions at specific chromosomal locations like 8p23.1, and conditions such as Wolf-Hirschhorn syndrome.8PubMed Central. Congenital diaphragmatic hernia and cleft lip and palate: looking for a common genetic etiology A diaphragmatic hernia that appears alongside other birth defects, such as heart malformations or cleft palate, is more likely to have a detectable genetic cause than an isolated hernia.9PubMed Central. Genetic causes of congenital diaphragmatic hernia
For families, this matters in practical terms. When a baby is born with a Bochdalek hernia, genetic testing can help clarify whether additional anomalies are part of a broader syndrome and can inform counseling about the chance of recurrence in future pregnancies.
Signs in Newborns
In a newborn with a large Bochdalek hernia, the signs are usually dramatic and immediate. Within minutes of birth the baby struggles to breathe, may appear blue, and has a visibly sunken abdomen because much of its contents have shifted into the chest. A stethoscope placed on the affected side picks up bowel sounds where lung sounds should be, and the heart may be pushed to the opposite side. These babies are intubated and placed on a ventilator right away.
Not every case is so obvious. Some smaller defects produce only mild respiratory difficulty or recurrent infections in infancy or childhood and may not be diagnosed until later in life. In these late-presenting children, symptoms can mimic asthma, pneumonia, or gastrointestinal problems, which can delay diagnosis.
When a Bochdalek Hernia Shows Up in Adults
A Bochdalek hernia in an adult is almost always one that was present since birth but small enough to stay clinically silent for years. A large review of over thirteen thousand abdominal CT scans found incidental Bochdalek hernias in about 0.17 percent of patients, with an average age of nearly 67 and none experiencing symptoms.10PubMed. Prevalence of incidental Bochdalek’s hernia in a large adult population These hernias tend to be small and contain only a bit of fat or a sliver of kidney.
When adult Bochdalek hernias do cause trouble, pain is the dominant complaint, reported in roughly 70 percent of symptomatic cases. Overall, about 86 percent of adults who are diagnosed outside of incidental imaging have some symptom related to their hernia.11PubMed. Bochdalek hernia in the adult: demographics, presentation, and surgical management Symptoms range from vague chest or abdominal pain to shortness of breath, nausea, and in rare emergencies, bowel obstruction or strangulation when herniated bowel gets trapped and loses its blood supply.
Prenatal Detection and Predicting Severity
Most Bochdalek hernias in newborns are now caught before delivery, typically on a routine second-trimester ultrasound. The sonographer may see abdominal organs sitting in the chest, the heart displaced to one side, or a stomach bubble visible above the diaphragm. When ultrasound raises suspicion, fetal MRI can confirm the diagnosis and provide additional detail that ultrasound sometimes misses, particularly in assessing how much lung tissue has developed and which organs have herniated.12PubMed Central. The Benefits of MRI in the Prenatal Diagnosis of Congenital Diaphragmatic Hernia
Prenatal imaging also feeds into risk stratification. One widely used measure is the lung-to-head ratio, which compares the size of the lung on the unaffected side to the baby’s head circumference. This ratio, measured on ultrasound, helps predict how well the baby will do after birth. After delivery, scoring tools that incorporate early oxygenation measurements and blood-pressure support needs provide even sharper predictions. In one study, the first-day oxygenation index alone had excellent accuracy for distinguishing babies who would survive from those who would not.13PubMed. Postnatal predictors of mortality and derivation of a novel risk score in congenital diaphragmatic hernia The need for medications to support blood pressure and the presence of a collapsed lung before surgery are additional red flags.14PubMed Central. Survival and Predictors of Mortality of Congenital Diaphragmatic Hernia in Newborns at a Tertiary Care Hospital in Saudi Arabia
Stabilization Before Surgery in Newborns
Decades ago, a Bochdalek hernia in a newborn was treated as a surgical emergency. Surgeons rushed to close the defect, reasoning that getting the organs out of the chest as fast as possible would help the lungs expand. That approach has been largely abandoned. The modern strategy focuses on stabilizing the baby’s breathing and circulation first, then repairing the hernia hours or even days later.
Gentle ventilation is the cornerstone. Pressures are kept as low as possible, and slightly elevated carbon dioxide levels are tolerated rather than aggressively corrected, because high ventilator pressures damage the already fragile lungs.15PubMed. Improved results in patients who have congenital diaphragmatic hernia using preoperative stabilization, extracorporeal membrane oxygenation, and delayed surgery Babies whose blood oxygen levels remain dangerously low despite these measures may be placed on extracorporeal membrane oxygenation, commonly known as ECMO, a machine that takes over the work of the lungs temporarily by oxygenating the blood outside the body. In one center’s experience, this combination of delayed repair and ECMO for the sickest patients produced an overall three-month survival rate of 80 percent among high-risk infants.16PubMed Central. Delayed surgical repair and ECMO improves survival in congenital diaphragmatic hernia Nitric oxide, a gas that relaxes blood vessels in the lungs, and high-frequency oscillatory ventilation are additional tools available during the stabilization phase.
Fetal Tracheal Balloon Occlusion for Severe Cases
For fetuses with very severe hernias and extremely poor predicted outcomes, an intervention called fetoscopic endoluminal tracheal occlusion, or FETO, offers a way to encourage lung growth before birth. During this procedure, performed around the middle of pregnancy, a tiny balloon is placed inside the fetal windpipe using a thin camera inserted through the mother’s abdomen. The balloon traps fluid that the fetal lungs normally produce, and this trapped fluid stretches and stimulates lung tissue to grow. The balloon is removed around 34 weeks of gestation to allow the lungs to prepare for breathing at birth.17PubMed Central. Fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia
Results from early controlled studies were striking. In one comparison, about 53 percent of infants who received FETO survived versus roughly 6 percent in the control group, and severe pulmonary hypertension was about half as common in the treated babies.18PubMed. Comparison between fetal endoscopic tracheal occlusion using a 1.0-mm fetoscope and prenatal expectant management in severe congenital diaphragmatic hernia FETO is not without risks, including preterm premature rupture of membranes and preterm birth, and it is reserved for cases where the predicted survival with standard care is very low. Larger randomized trials have added nuance to these early findings, and FETO is still considered an evolving therapy available primarily at specialized centers.
Surgical Repair
Once a newborn is stabilized, the surgery itself involves returning the herniated organs to the abdomen and closing the diaphragmatic defect. For small defects, the edges of the diaphragm can be sewn together directly. Larger holes often require a patch, typically made of synthetic mesh or a biologic material, to bridge the gap. In neonates, the operation is most commonly performed through an incision in the abdomen, though thoracoscopic (camera-assisted through the chest) approaches are increasingly used.
In adults, both laparoscopic and open repairs are reported. One case involved an 8-by-10-centimeter defect repaired laparoscopically: the hernia contained the entire transverse colon, part of the descending colon, omentum, and part of the spleen. After dividing adhesions and reducing the hernia contents, a large composite mesh was secured over the defect. The patient was discharged within days and had no recurrence at six months.19PubMed Central. Laparoscopic repair of a Bochdalek hernia in an adult woman For right-sided hernias where the liver has migrated into the chest, a combined thoracic and abdominal approach may be necessary. In one such case involving a giant right-sided hernia, surgeons first freed the liver from adhesions to the pericardium through the chest, then repaired the diaphragm with sutures and mesh. The patient’s breathing difficulties resolved within a week.20Journal of Surgical Case Reports. Surgical treatment of adult right-sided giant Bochdalek hernia
For left-sided versus right-sided hernias, the traditional guidance has been to approach right-sided defects from the chest (because the liver complicates things from below) and left-sided defects from the abdomen, though the choice ultimately depends on the surgeon’s experience and the specifics of the hernia.5PubMed Central. Right-sided Bochdalek hernia in an adult: a case report
Long-Term Health After Neonatal Repair
Surviving the initial repair is only part of the story. Children who had a Bochdalek hernia repaired as newborns face a range of ongoing health concerns that require years of follow-up. In one large multidisciplinary clinic’s 15-year experience, the most common long-term issues included gastroesophageal reflux (about 42 percent of patients), neurodevelopmental delay (roughly 29 percent), asthma (about 24 percent), chest wall deformity (around 16 percent), scoliosis (about 11 percent), and hernia recurrence (about 11 percent).21Journal of Pediatric Surgery. Standardizing follow-up in a multidisciplinary congenital diaphragmatic hernia clinic: A 15-year institutional experience
Lung function deserves special attention. About a quarter of survivors develop obstructive airway problems and a similar proportion develop restrictive lung patterns. Over a several-year follow-up window, lung function stabilized or improved in most children, but about 18 percent showed worsening obstruction over time. Factors associated with worse lung function include right-sided hernia, a large defect, liver herniation into the chest, and having needed ECMO.22PubMed Central. Long-Term pulmonary function outcomes in survivors of congenital diaphragmatic hernia
Neurodevelopmental outcomes are an underappreciated concern. Even among survivors who never needed ECMO, high rates of learning disabilities, attention difficulties, and problems with executive function have been documented. Social difficulties and weaknesses in mathematics were more common compared with peers, and low carbon dioxide levels during the perioperative period were linked to worse cognitive outcomes later.23PubMed. Long-term neurodevelopmental outcomes of congenital diaphragmatic hernia survivors not treated with extracorporeal membrane oxygenation These findings underscore why most specialized centers now recommend long-term multidisciplinary follow-up, not just with surgeons and pulmonologists but with developmental specialists and psychologists.
Racial and Socioeconomic Disparities in Outcomes
Not all families face the same odds when a baby is born with a Bochdalek hernia, and the reasons extend well beyond biology. Research consistently shows that Black infants with congenital diaphragmatic hernia have worse survival than white infants. In one study, Black infants born to mothers in higher-poverty neighborhoods were nearly three times as likely to die as Black infants born in low-poverty areas, while neighborhood poverty had no measurable effect on white infants’ survival.24PubMed Central. Survival Disparities Associated with Congenital Diaphragmatic Hernia
A more recent analysis attempted to disentangle these effects. Low socioeconomic status explained about 17 percent of the mortality gap between Black and white infants, but unmeasured factors related to maternal race accounted for the majority of the difference, roughly 76 percent, pointing to systemic issues that go beyond income alone.25PubMed Central. The Impact of Race and Ethnicity on Congenital Diaphragmatic Hernia 1‐Year Mortality Hospital-level factors matter too. Lower-volume treatment facilities, which are more likely to serve non-white Hispanic patients and families near the U.S.-Mexico border, carry higher mortality rates. Each additional case a facility treats per year is associated with a small but meaningful reduction in the odds of death.26PubMed. Treatment Facility Case Volume and Disparities in Outcomes of Congenital Diaphragmatic Hernia Cases For families, the practical takeaway is that delivery at a high-volume center with ECMO capability and a dedicated surgical team can materially affect outcomes.
How the Condition Got Its Name
The hernia takes its name from Vincent Alexander Bochdalek, a Czech anatomist who described the posterolateral diaphragmatic defect in 1848. He was not the first to observe it, though. A physician named McCauley described the condition nearly a century earlier, in 1754.27Annals of Medicine and Surgery. Bochdalek hernia in a young adult successfully treated with a laparoscopic approach, a case report Bochdalek’s contribution was a more systematic anatomical characterization that stuck in the medical literature. Treatment has evolved enormously since then: for most of the twentieth century, immediate surgical repair was the standard, and mortality was grim. The shift toward preoperative stabilization, gentle ventilation, and ECMO over the past few decades has transformed survival rates, particularly at specialized centers. Fetal therapy, still relatively young as an approach, represents the latest chapter in that evolution and continues to be refined through ongoing trials.