A hernia is defined as the protrusion of an organ through an opening located on the structure that contains the organ. A Bochdalek hernia develops when abdominal organs push through a defective location of the diaphragm and protrude into the thoracic cavity.
The clinical picture exhibited by patients bearing a Bochdalek hernia fluctuates between the absence of symptomatology and severe complications. The symptoms that arise may be induced by the abnormally positioned internal organs or the respiratory distress their dislocation causes .
Symptoms relate to gastrointestinal malfunction include nausea, abdominal pain, constipation and others, whereas pulmonary compromise may be followed by symptomatology such as dyspnoic phenomena, thoracic pain or wheezing sounds. As for the course of the disease, it may display a periodic nature, with remission of symptoms at certain intervals. On the other hand, a large number of patients, almost half of them, present acutely with critical complications, such as organ strangulation . These patients have increased mortality and may even experience sudden death caused by strangulated organs. Another infrequent yet possible complication is a hernia-induced gastric volvulus.
It is common for a patient with a Bochdalek hernia to experience no symptoms, in which case the herniation will probably be diagnosed incidentally during a test conducted for other reasons. If the hernia does produce symptoms, those are generally non-specific indications of gastrointestinal or pulmonary dysfunction. A plain radiograph will most of the times illustrate a mass consisting of soft tissue or an intestinal loop filled with air that lies above the diaphragm; however, since these findings can be misinterpreted as various other pathologies related to the thorax, a computerized tomography scan is mandatory for a definitive diagnosis. Barium or gastrographin meal and enema can be also applied and are able to safely diagnose a diaphragmatic hernia of any size. A definitive diagnosis and accurate detection of the location of the hernia are important, because of the need to plan an appropriate surgical approach in order to treat the visceral herniation.
A Bochdalek hernia is treated surgically, aiming at the reduction of the abdominal contents and the correction of the initial defect that lead to the development of the hernia. Approaches vary depending on the size and location. Herniation that takes place on the right side of the diaphragm is treated with a thoracic approach or a combination of a thoracic and abdominal approach. On the other hand, hernias of the left section of the diaphragm are more challenging in terms of surgical intervention: a thoracic approach is implemented by some surgeons, because it allows for a better elimination of adhesions between the chest organs and the pouch of the hernia. Others, on the other hand, conduct a laparoscopic surgical procedure to better handle a malrotation incident. At any case, a mesh is used to compensate for the opening on the diaphragm and pain must be appropriately managed during the period after surgery, alongside respiratory monitoring.
Mortality rates associated with congenital diaphragmatic hernias have been exhibiting a steady decline, thanks to the advent of new and progressive treatment techniques, as well as diagnostic modalities that help to diagnose the defect in patients without symptoms . Significant morbidity does not arise as a result of the hernia itself, but due to the underlying conditions that it is associated with, such as neurodevelopmental disorders.
Bochdalek and Morgagni hernias are the two types of congenital diaphragmatic hernias. Almost 97% of congenital diaphragmatic hernias are of the Bochdalek type . They are located posteriorly and are a result of a defective diaphragm continuity; defects are caused by an underdeveloped pleuroperitoneal membrane or a failure of the diaphragm's musculature to migrate.
The degree of herniation and subsequent symptomatology plays a role in the number of Bochdalek hernias diagnosed amongst the general population. Such hernias are rarely diagnosed in the adult life; however, pediatric patients diagnosed with a Bochdalek hernia until the age of 1 year old run a greater risk of death due to respiratory compromise. According to necropsical data  , the Bochdalek hernia has an incidence amounting from 1/2000 to 1/7000; CT- derived data, on the other hand, illustrate a potential incidence that can reach 6% .
From a pathophysiological point of view, a Bochdalek hernia develops when an organ that is normally confined within the abdomen protrudes through the diaphragm. The diaphragm acts as a natural barrier that separates the thoracic from the abdominal cavity and consists of muscle and fibrous tissue. During the course of fetal development, the septum transversum, the cervical myotomes, the dorsal mesentery and the pleuroperitoneal membranes are the components from which the diaphragm is built.
The diaphragmatic anatomical structure is expected to be fully matured by the 8th week of pregnancy. Congenital defects, such as impaired pleuroperitoneal membrane closure or migration of muscle cells, result in a diaphragmatic structure that lacks the complete set of characteristics needed to prevent the sliding of the organs from one cavity to another. Hence, the diaphragm is vulnerable and allows the protrusion of intra-abdominal organs through its structures.
As far as general diaphragmatic anatomy is concerned, the arterial supply to the diaphragm is conducted via the phrenic arteries (left and right), intercostal arteries and branches of the internal thoracic arteries. It is innervated by the phrenic nerve: originating from the 4th cervical ramus, this nerve follows a lengthy route before it reaches the diaphragm and therefore, any obstacle or damage sustained at any point of the route leads to problems associated with the diaphragm itself .
A Bochdalek hernia cannot be prevented, as it is caused by developmental defects during the formation of body structures in an embryo.
The segregation between the abdominal cavity and the thoracic space is achieved by the diaphragm, which keeps the organs in their appropriate place. Occasionally, the posterior diaphragmatic attachment is impaired, because the pleuroperitoneal membrane fails to close during fetal development. This particular location is responsible for herniation phenomena, since the structure fails to restrain organs and keep them in place. A Bochdalek hernia is formed when organs located in the abdomen and especially the intestines and stomach, protrude through the posterior defective region of the diaphragm. This type of hernia occurs primarily on the left posterior diaphragmatic side at a rate of 85%.
A significant protrusion of an abdominal organ into the thoracic cavity usually causes symptomatology related to pulmonary function, as the lung will also be defective due to lack of space . This constitutes a severe complication, as an infant may well succumb to respiratory arrest, if the hernia remains undiagnosed and the lung is extremely compromised.
Bochdalek hernias are mostly diagnosed during infancy; in adults they are quite rare, with only a hundred known cases of adult Bochdalek hernias worldwide . A Bochdalek hernia constitutes 0.2 to 6% of all hernias of the diaphragm . During the past years, with the advent of computerized tomography imaging (CT), the number of Bochdalek hernias diagnosed has exhibited an increase. The other type of congenital diaphragmatic hernia is the Morgagni hernia, where an intra-abdominal organ protrudes into the thoracic cavity through the foramen of Morgagni. This type of hernia is located anteriorly and is rarer than a Bochdalek hernia.
The optimal way of treating a Bochdalek hernia is surgery; a thoracic approach, an abdominal one or a combination of the two are used to achieve a permanent repairment of the diaphragmatic opening via a mesh and relocate the protruding organ into its normal cavity.
A Bochdalek hernia is a congenital anomaly, in which abdominal organs protrude through the diaphragm into the thoracic cavity. The diaphragm is a structure that separates the chest are from the abdomen and prevents the translocation of internal organs, while at the same time providing openings, so that organs (such as the esophagus) can pass through.
During the development of the fetus in the womb, various abnormalities of the diaphragm may render it unstable and weak at some locations. Pressure from internal organs, combined with the congenital defects of the diaphragm lead to the formation of openings, through which organs found in the abdomen, most commonly the stomach and intestine, actually find their way up to the chest. Depending on the size and location of the hernia, lungs may be subject to distress, leading to pulmonary dysfunction.
Bochdalek hernias are congenital and are mostly diagnosed during the first year of a child's life. They are only rarely detected during the adult life. A patient may experience no symptoms caused by the hernia, or alternatively, they may report symptoms attributed to the gastrointestinal system or the pulmonary system. While an internal organ protrudes through a narrow opening, its function is distorted: it may be strangulated and the flow of its contents hindered. That is why a Bochdalek hernia may cause bowel obstruction, nausea and abdominal pain. If an abdominal organ is severely strangulated, the condition is treated as a medical emergency. On the other hand, the lungs lack the adequate space they need to function in case an organ ascends into the thoracic cavity and related symptomatology includes chest pain and dyspnea amongst others.
A Bochdalek hernia is diagnosed non-invasively, with the use of x-ray scans, a CT scan or a barium enema. Imaging modalities help to differentiate such a hernia from other abnormalities of the chest. Its treatment is surgical; the location may be accessed through the abdomen or thorax, either in an open fashion or laparoscopically.