The diaphragm divides the thorax from the abdomen and is derived from several sources during embryological development, mainly the septum transversum. This is situated at first rostrally to the somites in the embryonic period and acts as a mesodermal bridge between the pericardial and the umbilical vesicle cavities. Its cranial portion becomes covered by pericardium and pleura, whereas its ventral part is a sagittal mesentery that contains the expanding liver. The septum transversum gives rise to the majority of the diaphragm and descends from the cervical to thoracic level during embryonic development. Normal diaphragm closure occurs at the eighth week.
The other parts of the diaphragm consist of the pleuroperitoneal membranes and the mesenchyma of the body wall. The pleuroperitoneal canals may be closed by the contribution of the subjacent organs, such as the liver and the suprarenal glands. The skeletal muscle of the diaphragm is probably derived in situ from the body wall and also through the migration from cervical myotomes.
The CDH is a displacement of the abdominal organs into the thoracic cavity through a weak area or a distinct defect in the diaphragm. The causes of precipitating viscera herniation may be related to mechanical or pressure changes in the thoracoabdominal cavities. The most frequent types of diaphragmatic hernia are the left posterolateral (Bochdalek hernia) and the sternocostal (Morgagni hernia) types. A Bochdalek hernia, resulting from inadequate closure of the posterolateral pleuroperitoneal membrane, is the most frequently seen congenital diaphragmatic hernia. Defects occur more frequently on the left side than on the right side of the diaphragm, and the abdominal contents, including stomach, bowel loops, liver, spleen or fat tissues, may be displaced into the thoracic cavity. A posterolateral hernia on the right side is very rare and this is probably attributable to the protection provided by the liver. Foramen of Morgagni hernias are rare diaphragmatic hernias, usually occurring on the right and located in the anterior mediastinum because of the retrosternal location of the foramen of Morgagni, described as an anterior diaphragmatic defect. In adults, foramen of Morgagni hernia is also associated with obesity, trauma, weight lifting, or other causes of increased intra-abdominal pressure.
The most frequent cause of herniation of the abdominal viscera in adults seems to be trauma, whereas in babies or newborns it is most often attributable to congenital absence or defective fusion of the septum transversum or the pleuroperitoneal membrane. The detection of diaphragmatic hernia is made with pre-natal ultrasonography in 50 percent to 90 percent of cases
]. The intestine and the liver may be in the thorax and the lungs are small. Ultrasound scans allow detailed assessment of the heart. Lung growth is measured as a proportion of head growth. The lung-to-head ratio (LHR) has some prognostic value
], because when it is below 1, survival is compromised
]. When diagnosis is made in utero
, amniocentesis is often performed for detecting chromosomal aberrations
] and may help to estimate lung maturity
]. After birth, a diagnosis can readily be made on the basis of symptoms and physical signs. A plain X-ray of the thorax and abdomen provides details of the position of the herniated viscera. Blood gases and pH status reflect the efficiency of gas exchange. A physical examination may be sufficient, but passing a naso-gastric catheter into the stomach before a plain X-ray of the thorax and abdomen may help to locate it or to detect any esophageal displacement
]. In some rare cases, herniation of viscera through the diaphragm is an incidental finding in adult patients undergoing plain X-ray films or CT scans for other symptoms not related to this pathology. Since our three adult patients had asymptomatic or poorly symptomatic diaphragmatic hernia we did not refer the herniation to any traumatic event and so the diaphragmatic defects were, presumably, congenital. A large proportion of fetuses with CDH are diagnosed in utero
and termination of gestation is sometimes preferred, particularly when chromosomal aberrations and syndromes are present
]. The possibility of fetal instrumentation directed to alleviate the consequences of the herniation is becoming a progressively more acceptable alternative. The current development of minimally invasive surgery has brought about the immediate effect of making fetendoscopic balloon tracheal occlusion possible in fetuses with LHR below 1
]. Experimental and clinical evidence suggest that biochemical lung maturation is delayed in fetuses with CDH
] and this led to the assumption that this process is accelerated by administration of maternal corticosteroids as carried out for premature deliveries. However, since the evidence of the benefits of this medication are not totally convincing
], a multicenter trial could be useful
Whenever pre-natal diagnosis is made, gestation should be prolonged until near term if possible
] and there is no evidence of the benefits of delivery by Caesarean section
]. Treatment after birth requires extra-corporeal membrane oxygenation (ECMO) prior to surgical correction. Extra-corporeal membrane oxygenation can be seen as a safety net maintained until proper gas exchange occurs. Cannulation of both the right carotid artery and jugular vein and connection to a circuit with a membrane gas exchange chamber allows oxygenation and CO2
disposal without participation of the lung, which is thus preserved from any pressure insult
]. This technique is probably a good adjunct in a limited number of patients in whom predicted severe lung hypoplasia would make adequate gas exchange impossible or in those in whom reversal to the fetal pattern of circulation becomes unmanageable. In the past, surgical repair of CDH used to be a life-saving emergency procedure. It is presently accepted that this procedure should be undertaken only once cardio-respiratory functions have been stabilized. A policy of delayed surgery coupled with gentle ventilation and occasional ECMO support has yielded the best results to date. The goal of all forms of pre-operative treatment is to obtain ‘stabilization’ of the patient: this requires acceptable oxygenation and CO2
disposal with stable pulmonary pressures, tolerable shunting, good myocardial function and adequate renal clearance with reduced or withdrawn inotropic drugs. Under general anesthesia, a subcostal or transverse abdominal incision is made and the herniated viscera are carefully reduced into the abdomen: the diaphragmatic orifice is closed with interrupted sutures without leaving an intercostal tube. A tube was routinely used in the past
] until it was realized that underwater seals cause increased respiratory work and overdistension of the hypoplastic lung that may reduce ventilation even further. A tubeless policy was then advised
]. When the defect is too large, a prosthetic patch is used to achieve closure
]. It is sutured to the rims of the orifice with interrupted sutures and, to avoid excessive tension and enlargement of the hemi-thorax, cone shaping of the patch can be beneficial
]. The use of a patch seems to increase the risk of re-herniation
] although it should be acknowledged that patients requiring a patch have larger defects that entail higher morbidity
]. Abdominal wall or dorsi muscle flaps have also been used for CDH repair
]. Since the advent of minimally invasive surgery (MIS) thoracoscopic
] or laparoscopic
] approaches have been proposed for CDH repair. MIS is a good approach in cases diagnosed during infancy with less severe symptoms. Regardless, some concerns about this particular approach in the newborn period have been expressed on the basis of excessive peri-operative hypercapnia and prolonged post-operative low brain oxygenation. The risk of recurrence after a minimally invasive approach has been found to be similar to that of open surgery.
Congenital diaphragmatic hernias mainly present in the neonatal period and are associated with a mortality that has not changed much despite the advances made in critical care. Rarely, these hernias present later in life, some even in adulthood. There are numerous reports of CDH presenting after infancy. These patients are either asymptomatic or have minimal respiratory symptoms, possibly because the lungs are not hypoplastic.
Late-presenting CDH is often difficult to diagnose, and delays in treatment are common. All diaphragmatic defects could be closed by an abdominal approach without post-operative complications. Clinical symptoms disappeared post-operatively. In adulthood a CDH may present with gastrointestinal tract symptoms that may include intermittent abdominal pain, vomiting, and dysphagia. Respiratory symptoms usually include dyspnea and chest pain
]. Symptoms may be intermittent or acute depending on the extent of herniation of abdominal viscera into the thorax. An acute presentation is usually due to incarceration, obstruction, or strangulation of the herniated viscera
]. Diagnosis is ascertained by a combination of chest X-rays, CT and magnetic resonance imaging (MRI), as well as upper gastrointestinal and bowel double-contrast studies. Typical findings on a CT scan would be the abutment of fat or soft tissue along the upper surface of the diaphragm, characteristic posterolateral location on the hemidiaphragm, diaphragmatic discontinuity adjacent to the mass, and continuous density above and below the diaphragm through the defect
]. Bochdalek hernia may be misdiagnosed as pleural effusion, pneumonia, tension pneumothorax, lung cysts, or atelectasis.
A careful analysis of chest films and a thorough search for connecting bowel segments passing through the diaphragmatic defect may help to avoid incorrect diagnosis and an undesirable delay in treatment. Confusion with pneumonia or pneumothorax can be diminished by placing a feeding tube and instillation of contrast material.
Management of a Bochdalek hernia includes reducing the abdominal contents and repairing the defect through a laparotomy or thoracotomy. Successful laparoscopic and thoracoscopic repairs of Bochdalek hernias have both been described. Right-sided defects are usually dealt with by a thoracic or thoracoabdominal approach because of the presence of the liver. For left-sided hernias some authors suggest a transthoracic approach while others advise a transperitoneal approach
]. The indications for repair of congenital diaphragmatic hernia are the same as those to treat any hernia, and should take into account the patient’s overall medical condition. The outcome of adult patients suffering from Bochdalek hernia depends on the type of clinical presentation. Delay in the diagnosis of CDH can result in significant morbidity