What is Congenital Diaphragmatic Hernia?
Congenital Diaphragmatic Hernia (CDH) is a group of disorders that involve congenital malformation of the diaphragm. A malformed diaphragm lets the abdominal organs push into proper lung formation. It is a major life-threatening condition in infants.
Most deaths associated with it are caused by two complications, namely:
- Pulmonary hypertension
- Pulmonary hypoplasia
Congenital Diaphragmatic Hernia Epidemiology
CDH is a rare condition, affecting only 1 person in every 2000 to 5000 live births. It accounts for almost 8% of all major inborn or congenital abnormalities. The risks associated with recurrence of isolated CDH in the future siblings is around 2%. Familial CDH is very rare (less than 2% of all reported cases) and both the autosomal dominant and autosomal recessive inheritance patterns have been reported. The left side of the body is affected in most cases. Bochdalek hernia is somewhat more commonly observed in males than females, whereas Morgagni hernia occurs more frequently in females than males.
Congenital Diaphragmatic Hernia Types
There are various types of CDH, the most common of which is Bochdalek hernia. The other forms include:
- Morgagni hernia
- Central tendon defects
- Diaphragm eventration
It is the most commonly occurring form of CDH, observed in more than 96% of all cases. It is also referred to as postero-lateral diaphragmatic hernia. In this type, the diaphragm anomaly involves a hole or perforation in the postero-lateral part of the diaphragm that allows passage of abdominal viscera into chest cavity. Most cases of Bochdalek hernias (i.e. around 80% to 85%) occur on left-hand corner of the diaphragm, whereas a large number of remaining cases occur on right side.
It accounts for almost 2% of all cases of CDH. It involves herniation through foramina of Morgagni located just adjacent to xiphoid process of sternum. The majority of these hernias develop on the right part of the body. Morgagni hernia is also known as parasternal or retrosternal hernia.
A congenital diaphragmatic eventration occurs when partial or complete abnormal displacement or elevation of a generally intact diaphragm takes place into chest cavity. It is a rare form of CDH which occurs because the diaphragm is comparatively thinner in the area of eventration which allows upward protruding of the abdominal viscera.
Congenital Diaphragmatic Hernia Causes
CDH occurs as a result of improper joining of the structures during the fetal development. Due to this reason, the abdominal organs like the stomach, spleen, small intestine, kidney and portions of the liver appear in chest cavity. Hence, the lung tissue present on the affected area is not allowed to develop completely.
The diaphragm develops initially as a septum or divider between heart and liver, which progresses postero-laterally and closes finally at left Bochdalek foramen by 8th to 10th gestational week. Herniation of the viscera occurring in severe CDH is postulated to take place during pseudo-glandular stages of lung development. Pulmonary hypoplasia is caused by lung compression that is most critical on ipsilateral side, even though both of the lungs might be abnormal. Signs of pulmonary hypoplasia are associated with lesser alveoli, bronchial generations and arterial generations.
Fetal exposure to the chemical nitrofen leads to variable amounts of lung hypoplasia. CDH may also occur as an isolated or nonsyndromic defect. Familial factors are involved in less than 2% of these cases. Various forms of genetic inheritance, such as autosomal dominant, autosomal recessive and X-linked patterns have been discussed in association with such instances.
More than 10% cases of CDH are linked with some form of underlying syndromic diagnosis, even though few genetic mutations are recognized currently. Chromosomal anomalies have been found in almost 30% of infants having CDH, which has been closely associated with other conditions such as:
- Trisomy 13
- Trisomy 21
- Trisomy 18
- Turner Syndrome
Chromosome deletions on the chromosomes 8p, 15q and 1q have also been reported in relation to CDH. Deletions of the chromosomes 15q and 8p appear to be linked with heart malformations. Deficiencies in the availability of vitamin A and metabolism have been associated with CDH as well.
Congenital Diaphragmatic Hernia Pathophysiology
CDH involves 3 major defects:
- Pulmonary hypoplasia
- Herniation of abdominal parts into the chest
- Inability of the diaphragm to close completely during development
CDH is usually characterized by varying degrees of pulmonary hypoplasia that is associated with a reduction in the cross-sectional area of pulmonary vasculature as well as alterations in the surfactant system. Lungs are accompanied by a small-sized alveolar capillary membrane that helps in gaseous exchange, which can be further reduced by surfactant dysfunction. Along with parenchymal disease, another notable anomaly is the increased muscularization of intraacinar pulmonary arteries. Left ventricular hypoplasia can be observed in the most severe cases. There might be reduced pulmonary capillary blood flow due to the smaller cross-sectional area of pulmonary vascular bed. The flow might be further hindered by abnormal pulmonary vasoconstriction.
Congenital Diaphragmatic Hernia Symptoms
Infants with CDH usually present symptoms such as cyanosis and respiratory distress during the first moments or first few hours of life; however these problems may be exhibited later as well. The signs of respiratory distress might be severe and have a correlation with circulatory insufficiency, which requires aggressive resuscitative measures.
A restricted flow of blood through the lungs is believed to be caused by the abnormalities in the lung system. Pulmonary hypoplasia or reduced lung volume is related to the presence of abdominal organs in chest cavity which leads to reduced size of the lungs, especially along the side of hernia.
Other common signs and symptoms of CDH include:
- Scaphoid abdomen
- Barrel-shaped chest
- Grunting respirations
- Tachycardia or fast heart rate
- Tachypnea or rapid breathing
Auscultation of lungs occurring in left-sided postero-lateral hernia leads to poor entry of air on the left, along with shifting of the cardiac sounds over to the right chest. Patients having severe defects may present with signs of pneumothorax (i.e., poor air entry and poor perfusion).
The following signs may indicate a syndromic CDH:
- Spinal dysraphism
- Extremity abnormalities
- Craniofacial dysmorphisms
Congenital Diaphragmatic Hernia Diagnosis
The following tests are conducted to see if an infant is born with CDH:
- Ultrafast fetal MRI
- Chest radiography
- Cranial sonography
- Doppler imaging tests
- Renal ultrasonography
- Cardiac ultrasonography
- Continuous pulse oximetry
- Skin biopsies (in some rare cases)
- High-definition level II ultrasound
- Cranial magnetic resonance imaging
- Chromosome studies, such as microarray analysis
- Levels of serum glucose, electrolytes and ionized calcium
- Arterial blood gas (ABG) measurements, for checking the levels of pH, PaO2 and PaCO2
- Serum lactate; can help in the evaluation of circulatory insufficiency and/or severe hypoxemia that is related to tissue hypoxia
CDH can also be diagnosed prenatally by using ultrasonography.
Congenital Diaphragmatic Hernia Differential Diagnosis
A number of disorders are manifested by symptoms which can overlap with those of CDH. Hence, it is necessary that the diagnostician differentiates it from such conditions in order to come up with a precise diagnosis. The differential diagnoses of CDH include isolating its symptoms from those of other conditions such as:
- Hybrid lesions
- Pleural effusion
- Gastric volvulus
- Neurenteric cysts
- Bronchogenic cysts
- Lung bullae and cysts
- Aspiration syndromes
- Pulmonary sequestration
- Massive pleuropneumonia
- Cystic mediastinal teratoma
- Disorders of the Thoracic Cavity and Pleura
- Persistent Newborn Pulmonary Hypertension
- Type I CCAM (congenital cystic adenomatoid malformation)
Congenital Diaphragmatic Hernia Associated Disorders
A number of disorders are frequently associated with CDH. These include:
- Trisomy 18
- Trisomy 13
- Trisomy 21
- Spina bifida
- Fryns syndrome
- Neural tube defects
- Pulmonary hypoplasia
- Cornelia de Lange syndrome
- Congenital cardiac anomalies
- Turner syndrome – monosomy X
- Bronchopulmonary sequestration
- Pallister-Killian syndrome – tetrasomy 12p
Congenital Diaphragmatic Hernia Treatment
The first steps in managing CDH involve placing an orogastric tube and using intubation to secure the airway. The baby is generally placed immediately on a ventilator. Extracorporeal membrane oxygenation or ECMO has been employed as a part of treatment strategy in some hospitals and medical institutions. Extracorporeal membrane oxygenation is like a heart-lung bypass for a baby, although it has also proven to be effective when used in older children. Doctors insert a cannula inside the carotid artery that allow the blood to come out of the body and start passing through ECMO circuit, which is then scrubbed, fully oxygenated and then passed through a certain filter before it is returned back to the body through a 2nd cannula into the baby’s own circulatory system. Here the blood is circulated before being returned again to ECMO circuit to be filled with oxygen again. So in essence, an ECMO circuit operates as lungs for the baby. The affected baby needs extra volumes of blood and high doses of blood thinning medications that can keep the circuit of blood running without any formation of clots which could be fatal.
An oscillating ventilator should be used even when a baby is not making use of her lungs, as this prevents the lungs from collapsing fully while not in use. The pulmonary artery gets an opportunity to rest during the ECMO procedure, which reduces the possibility of pulmonary hypertension, a major complication of the CDH cases. Congenital diaphragmatic hernia repair can be carried out while a baby is kept on ECMO, even though the blood-thinning medications increase the risks. Normally, surgeons prefer performing CDH repairs when ECMO is not in use. As soon as a baby is taken off the ECMO, doctors seal off the carotid artery which can then no longer be utilized. An incision or cut is made in abdomen while repairing the hernia. Sometimes, the hernia can simply be stitched closed; however, a patch might be necessary in more complicated instances. A synthetic patch might be used which will require later to be replaced as the child matures. A natural patch can also be designed by slicing and then folding over a small section of the abdominal muscle and then attaching it to the existing piece of diaphragm. If there is any organ displacement, it is rectified during surgery. The lungs and heart will normally move back into appropriate positions on their own as soon as the displaced organs like the liver, bowels, or stomach move away. The incision is closed after that. On some occasions, the site of incision is intentionally left open so as to allow the body of a baby to adjust or cope with the newly moved organs as well as the pressure that it creates. The incision is then closed later as the swelling and drainage gets reduced.
Diaphragm eventration is normally repaired thoracoscopically, by using a method known as plication of the diaphragm. This mainly involves folding of eventrated diaphragm which then is sutured to adjust to the additional diaphragm tissue.
Other procedures include:
- Endotracheal intubation
- Mechanical ventilation
- Chest tube drainage
- Lung transplantation
The various types of drugs and medications used in the treatment of CDH are listed below:
- Dopamine (Intropin)
- Milrinone (Primacor)
- Dobutamine (Dobutrex)
- Fentanyl (Sublimaze, Duragesic)
Neuromuscular relaxing agents
- Vecuronium (Norcuron)
- Pancuronium (Pavulon)
- Nitric oxide (INOmax)
Pulmonary vasodilating agents
Congenital Diaphragmatic Hernia Complications
The primary complications occurring due to CDH are:
- Pulmonary hypertension
- Pulmonary hypoplasia
Other problems that are seen in CDH patients include:
- Severe respiratory distress
- Gastroesophageal reflux
- Other congenital problems
The following complications may emerge as a result of CDH repair:
- Collapsed lung
- Respiratory failure
- Reactions to medicines
- Persistent lung problems
- Severe breathing problems
Congenital Diaphragmatic Hernia Prognosis
The outcome depends on the overall development of the lungs of affected babies as well as the presence of any other major congenital problems. Generally, the prognosis is positive for infants having enough lung tissues and no other associated health problems.
Congenital Diaphragmatic Hernia Survival Rate
CDH has a mortality rate of around 40% to 62%. The outcomes are better when the patients do not have any other congenital disorders. With advances in medical treatment and surgery, the overall rate of survival is now more than 80%.
Congenital Diaphragmatic Hernia Pictures
The following images illustrate the areas of the body affected by this disorder.
Picture 1 – Congenital Diaphragmatic Hernia
Picture 2 – Congenital Diaphragmatic Hernia Image