Congenital Diaphragmatic Hernia (CDH) Imaging 

Updated: May 07, 2020
  • Author: Ali Hekmatnia, MD; Chief Editor: Eugene C Lin, MD  more...
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Practice Essentials

Congenital diaphragmatic hernia (CDH) is a major surgical emergency in newborns. The key to survival lies in prompt diagnosis and treatment. [1, 2, 3, 4] In the United States and worldwide, this condition occurs in about 1 of every 2000-4000 live births and accounts for 8% of all major congenital anomalies. Congenital diaphragmatic hernia is by far the most often diagnosed diaphragmatic pathology, but unilateral or bilateral eventration or paralysis can also be identified. [5, 6, 7]  Bochdalek hernias result from a defect in the posterolateral area of the diaphragm and constitute 70-75% of CDHs; the majority occur on the left side. Morgagni hernias result from a defect in the anteromedial part of the diaphragm and constitute 20-25 of CDH cases. Central hernias account for 2-5%. Bilateral defects are very rare and are associated with a poor prognosis. [8]

CDH diagnosis can be challenging, as the clinical symptoms are often nonspecific, with radiographic findings potentially mimicking other chest conditions such as pneumonia, pleural effusion, and pneumothorax. An incorrect diagnosis may expose the patient to unnecessary or harmful interventions such as thoracostomy tube placement. [9]

Mortality in babies with congenital diaphragmatic hernia has been reported to be 25-60% and is related to pulmonary hypoplasia, persistent fetal circulation (PFC), and associated anomalies. [10, 1, 2, 11] The identification of the stomach within the chest is correlated with a poor outcome, possibly as a result of herniation at an earlier stage of gestation that results in a greater degree of pulmonary hypoplasia. Poor outcomes have also been associated with pneumothorax (reflecting lung hypoplasia) and a right-sided defect, whereas favorable features include the presence of aerated ipsilateral lung and aeration in the contralateral lung of more than 50%. [10, 1]

In a study of by Style et al, MRI lung volumes at either the second or third trimester were predictive of morbidity, and second-trimester lung volumes strongly correlated with mortality. Total fetal lung volume (TFLV) was the only independent predictor of survival. Third-trimester MRI-derived lung volumes were independent predictors of,severity of pulmonary artery hyerpertension (PAH) and need for extracorporeal membrane oxygenation (ECMO). Interval TFLV growth was a strong predictor of PAH postnatally. [12, 13]

Benjamin et al reported a male preponderance in left-sided hernias, with a male-to-female ratio of 3:2, and the male-to-female ratio is 3:1 with right-sided hernias. [14]

Imaging Studies

In the prenatal period, ultrasonography has a high sensitivity in the detection of congenital diaphragmatic hernia. Bowel loops may appear to undergo peristalsis in the chest. [15]   Right-sided CDH can be difficult to diagnose because liver echogenicity is similar to that of lung tissue on ultrasound. In such cases, color Doppler ultrasound examination helps identify ductus venosus and intrahepatic vessels in the thoracic cavity. Fetal MRI is increasingly being used to assess CDH severity. [8, 16]

Prenatally diagnosed CDH is associated with larger defect sizes than that identified with a postnatal diagnosis; right-sided CDH is more often missed at prenatal ultrasound than postnatally (53% vs 35%). [17]  

In the neonatal and infantile periods, the importance of obtaining a chest radiograph at the first sign of distress cannot be overstated. This image usually permits an accurate diagnosis, although sometimes plain abdominal radiography is also needed for a precise diagnosis. Typically, no bowel gas is evident in the abdomen. In the classic radiographic appearance of CDH, the left hemithorax is filled with cystlike structures (loops of bowel), the mediastinum is shifted to the right, and the abdomen is relatively devoid of gas. [11]

In adults with CDH, previously undiagnosed Bochdalek hernias are most frequently identified when patients undergo CT scanning for reasons that appear to be unrelated to the hernia. 

MRI findings can be used to differentiate CDH from other chest masses, and MRI is superior to ultrasonography in demonstrating the position of the fetal liver above or below the diaphragm. 

(See the following images.)

Anteroposterior (AP) chest radiograph of a right-s Anteroposterior (AP) chest radiograph of a right-sided congenital diaphragmatic hernia (CDH) shows a mediastinal shift and lung compression caused by herniation of the liver and multiple bowel loops.
Anteroposterior (AP) chest radiograph of a right-s Anteroposterior (AP) chest radiograph of a right-sided congenital diaphragmatic hernia (CDH) shows herniation of the liver and bowel loops into the right hemithorax, with a shift of the heart and mediastinum to the left side.
Anteroposterior (AP) view of the abdomen in a pati Anteroposterior (AP) view of the abdomen in a patient with a congenital diaphragmatic hernia (CDH) shows a gasless pattern caused by herniation of bowel loops into the right hemithorax.
Anteroposterior (AP) view of the chest in a patien Anteroposterior (AP) view of the chest in a patient with a congenital diaphragmatic hernia (CDH) shows herniation of bowel loops into the left hemithorax, with a shift of the heart and mediastinum to the right side.

Classification of Congenital Diaphragmatic Hernia

The 3 basic types of congenital diaphragmatic hernia are posterolateral Bochdalek hernia (occurring in utero at approximately 6 weeks of gestation) [18, 19, 20] (see the image below), anterior Morgagni hernia, and hiatal hernia.

Anteroposterior (AP) view of the chest in a patien Anteroposterior (AP) view of the chest in a patient with a congenital diaphragmatic hernia (CDH) shows a left-sided Bochdalek hernia.

The major problem in a Bochdalek hernia is the posterolateral defect of the diaphragm, which results in either failure of the pleuroperitoneal folds to develop or improper or absent migration of the diaphragmatic musculature. Bilateral Bochdalek hernias are rare. [18]

Morgagni hernia is a less common form of congenital diaphragmatic hernia, occurring in only 5-10% of cases. This hernia occurs in the anterior midline through the sternocostal hiatus of the diaphragm, with 90% of cases occurring on the right side.

A congenital hiatus hernia is very rare in neonates. In this form, herniation of the stomach occurs through the esophageal hiatus.

Complications of Congenital Diaphragmatic Hernia

Several complications are associated with congenital diaphragmatic hernia and include the following

  • Pulmonary hypoplasia

  • Gastric volvulus

  • Rotational abnormalities and midgut volvulus

  • Hypoplasia of the left ventricle with a left-sided hernia or pleural effusions caused by right-sided involvement

  • Bilateral renal hypertrophy

  • Liver heterotopia

A study of 256 infants with CDH reported that marked stomach displacement on prenatal imaging is significantly associated with GI morbidity in left-sided CDH. According to the investigators, survivors of CDH who have large defects, who have had prolonged use of mechanical ventilation, or who have received ECMO may be at increased risk for GERD, gastroparesis, and major GI surgery. [21]  

Pulmonary hypoplasia

Pulmonary hypoplasia, which may be unilateral or bilateral, is a serious complication of congenital diaphragmatic hernia. This hypoplasia may result in a persistent fetal circulation [10] and is thought to result from long-standing intrauterine (embryonic) compression of the lungs by the hernia. Mortality in babies with congenital diaphragmatic hernia is largely confined to those with bilateral pulmonary hypoplasia; however, hypoplasia is always more severe in the lung ipsilateral to the hernia. The pulmonary vasculature is also affected to a greater degree than the bronchial tree. [10]

Hypoplasia of the lungs is most severe in infants with the largest and longest-standing hernias; these infants are less likely to survive after birth. If a diaphragmatic hernia develops toward the end of pregnancy or after birth, pulmonary hypoplasia does not occur. [2]

Gastric volvulus

Gastric volvulus can occur in early infancy as a complication of congenital diaphragmatic hernia, and it usually produces acute gastric obstruction. The radiographic findings usually consist of an inverted distended stomach.

Rotational abnormalities and midgut volvulus

Intestinal malrotation is commonly observed in children with congenital diaphragmatic hernia (30-62%); this condition occurs in 37-40% of the cases of right-sided congenital diaphragmatic hernia. Volvulus is a complication in a small minority of these cases. [22]

The radiographic findings of intestinal malrotation in congenital diaphragmatic hernia usually consist of a high gastrointestinal obstruction. The results of contrast-enhanced studies, either air or barium studies, confirm the level of obstruction, which is usually toward the third and fourth portions of the duodenum. If a midgut volvulus is present, a beaked or tapering deformity of the obstructed duodenum is seen. Similar findings can be demonstrated with ultrasonography. [11]

Hypoplasia of the left ventricle with a left-sided hernia or pleural effusions caused by right-sided involvement

Pleural effusion is believed to result from lymphatic obstruction secondary to the compressive effects of the hernia.

Bilateral renal hypertrophy

The kidneys are often enlarged and hyperplastic. [11] An embryonic liaison between the kidneys and the lungs has been suggested, wherein the kidney produces a pulmonary growth factor (proline) that influences normal lung development. Conversely, when the lung is hypoplastic, it produces a renotropic substance and causes the kidneys to hypertrophy.

Liver heterotopia

Liver heterotopia is a rare complication of CDH with a reported incidence of 4.2%. The left side predominance of liver heterotopia associated with CDH is likely explained by the fact that most CDHs occur on the left side. However, there is a female predominance (68.4%), despite the overall male predominance of CDH. [23]  

Other Problems to Be Considered

Congenital diaphragmatic hernia can also occur as a part of De Lange syndrome (an autosomal dominant disorder with microbrachycephaly and limb and digital anomalies) and as a part of Fryns syndrome (an autosomal recessive disorder with variable features that include diaphragmatic hernia, cleft lip and palate, and distal digital hypoplasia). Congenital diaphragmatic hernia can occur in association with cardiovascular, genitourinary, and gastrointestinal malformations. This condition may also be found in a variety of chromosomal anomalies, including trisomy 13, trisomy 18, and tetrasomy 12P mosaicism. [2, 14]

Other conditions that should be considered are cystic adenomatoid malformation, pneumatocele, and mediastinal cyst (bronchogenic, neuroenteric, thymic). Gastric or other intestinal perforations rarely occur.

Guidelines

The Canadian CDH Collaborative has developed evidence-based guidelines in an effort to standardize CDH care practices and improve outcomes. Imaging recommendations include the following [24] :

  • Ultrasound measurement of observed-to-expected lung–head ratio (O/E LHR) should be used between 22 and 32 weeks of gestational age to predict the severity of pulmonary hypoplasia in isolated CDH.
  • In left-sided CDH, an O/E LHR < 25% predicts poor outcome. In right-sided CDH, an O/E LHR < 45% may predict poor outcome.
  • Fetal magnetic resonance imaging should be used (where available) for the assessment of lung volume and liver herniation in moderate and severe CDH.
  • Two standardized echocardiograms, one within 48 hours of birth and one at 2–3 weeks of age, are needed to assess pulmonary vascular resistance, as well as left ventricular and right ventricular function. Additional studies may be conducted as clinically indicated.

In a study by Dutemeyer et al of fetuses with CDH with or without fetoscopic endoluminal tracheal occlusion (FETO), lung-to-liver signal intensity ratio (LLSIR) was found to be significantly correlated with the prediction of postnatal survival. However, measurement of observed-to expected total fetal lung volume (O/E-TFLV) was identified as being better in predicting postnatal outcome. [12]

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Radiography

In patients presenting in the neonatal and infantile periods, the classic radiographic appearance of congenital diaphragmatic hernia is one in which the left hemithorax is filled with cystlike structures (loops of bowel), the mediastinum is shifted to the right, and the abdomen is relatively devoid of gas (see the images below). [11] In some cases, a few loops of intestine can be seen in the abdomen, but more often only the stomach remains visible within the abdomen.

Anteroposterior (AP) view of the chest in a patien Anteroposterior (AP) view of the chest in a patient with a congenital diaphragmatic hernia (CDH) shows herniation of bowel loops into the left hemithorax, with a shift of the heart and mediastinum to the right side.
Anteroposterior (AP) view of the abdomen in a pati Anteroposterior (AP) view of the abdomen in a patient with a congenital diaphragmatic hernia (CDH) shows a gasless pattern caused by herniation of bowel loops into the right hemithorax.

Interestingly, the stomach may be in an abnormal location, often more central than one would expect. The abnormal positioning of the stomach may be helpful in differentiating congenital diaphragmatic hernia from those few cases of congenital cystic adenomatoid malformation (CCAM) in which the cysts are large enough to mimic the air-filled intestinal loops. [11] In CCAM of the lungs, the stomach and bowel are normal in position and appearance.

Diagnostic considerations

If the chest radiograph is obtained before any air has entered the herniated bowel, diagnosing this condition with accuracy may be difficult. Similar difficulties arise when the liver alone is in the right hemithorax. In either case, the involved hemithorax is partially or totally opacified, and the mediastinal structures are shifted to the other side. In this circumstance, a large pleural fluid collection or mass may be present; however, in most such cases, air soon enters the intestine, and this finding establishes the diagnosis. In other cases, the condition may be diagnosed by noting abnormal intrathoracic positioning of a nasogastric tube. [11]

Unusual findings

Unusual findings include a contralateral pneumothorax, contralateral collapse/consolidation, fluid in the chest, and the absence of a contralateral aerated lung. [11] If herniation occurs on the right, the intestine and liver or the liver alone may fill the right hemithorax. If the liver is in the chest, its normal silhouette is not generally seen in the abdomen.

Morgagni hernias

Classically, Morgagni hernias appear as unilateral, mediastinal, and basal masses containing a variety of abdominal organs, including air-filled loops of intestine. Occasionally, these hernias may be bilateral, and in rare cases, they may produce significant respiratory distress. Large anterior-central diaphragmatic hernias may produce elevation of the cardiac silhouette and bilateral bulges to either side of the lower mediastinum. Often, these herniations occur into the pericardial cavity. When this occurs, serious cardiorespiratory compromise can result. [3, 11]

Postsurgical repair findings

After the repair of a congenital diaphragmatic hernia, an ipsilateral ex vacuo pneumothorax is a universal finding on all chest radiographs obtained immediately after surgery in neonates. This finding is unaffected by the use of a chest drain. [10]

The degree of expansion of the ipsilateral lung is variable. Final radiographs at discharge usually demonstrate a mild ipsilateral shift of the mediastinum. In most cases, this indicates increased pulmonary hypoplasia in the ipsilateral lung.

The postoperative radiographic course for patients presenting in later childhood is different. The ipsilateral lung is frequently fully expanded on the first postoperative radiograph, and the diaphragm usually occupies a normal position. These findings indicate a lesser degree of pulmonary hypoplasia. [10]

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Computed Tomography

In adults with congenital diaphragmatic hernia, previously undiagnosed Bochdalek hernias are most frequently identified when patients undergo computed tomography (CT) scanning for reasons that appear to be unrelated to the hernia. These Bochdalek hernias usually contain retroperitoneal fat or a kidney. [4, 18, 19]

Some authors believe that, with the routine use of thin-section CT scanning on modern imaging equipment, the prevalence and characteristics of late-presenting Bochdalek hernia can be more accurately estimated [19, 25] ; however, small Bochdalek defects may occur in as many as 6% of older adults.

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Magnetic Resonance Imaging

MRI can accurately depict congenital diaphragmatic hernia and permits an easy diagnosis. MRI findings can be used to differentiate this condition from other chest masses, and MRI is superior to ultrasonography in demonstrating the position of the fetal liver above or below the diaphragm. MRIs can clearly depict diaphragmatic discontinuity, a fetal compressed lung, and connecting bowel segments between the abdomen and chest. [26, 5]  

Most infants with congenital diaphragmatic hernia have at least 1 abnormality identified on MRI of the brain. In a study of 53 infants with congenital diaphragmatic hernia, 32 had at least 1 abnormality. The most common MRI findings were enlarged extra-axial spaces (36%), intraventricular hemorrhage (23%), ventriculomegaly (19%), white-matter injury (17%), and cerebellar hemorrhage (17%). The main predictors of brain injury were a requirement for extracorporeal membrane oxygenation, large diaphragmatic defect size, and lack of oral feeding at discharge. [27]

 

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Ultrasonography

Pregnant women carrying a fetus with congenital diaphragmatic hernia are often referred for ultrasonography first because of suspected polyhydramnios. The definite ultrasonographic diagnosis of fetal congenital diaphragmatic hernia lies on the visualization of abdominal organs in the chest; the ultrasonographic hallmark of this condition is a fluid-filled mass just behind the left atrium and ventricle in the lower thorax, as seen on a transverse view.

In patients presenting in the prenatal period, ultrasonographic features indicative of congenital diaphragmatic hernia include polyhydramnios, an absent or intrathoracic stomach bubble, a mediastinal and cardiac shift away from the side of the herniation, a small fetal abdominal circumference, the absence of the stomach in the abdomen, and, rarely, fetal hydrops. [15, 28, 29]

Fetal cardiac ultrasonography can provide useful information for predicting the outcomes of isolated left-sided congenital diaphragmatic hernia. The ratio of the diameter of the tricuspid valve to that of the mitral valve (TV/MV ratio) has been found to be a reliable indicator of outcomes of isolated left-sided congenital diaphragmatic hernia. A TV/MV ratio greater than 1.72 has been found to discriminate nonsurvivors from survivors with better sensitivity and specificity. [30]

In a right-sided hernia, the right lobe of the liver alone may be herniated (see the image below), or associated hydrothorax and ascites may be observed. [15]

Fetal ultrasound markers of congenital diaphragmatic hernia severity have been found to be predictive of significant morbidity and death. Lung-to-head ratio less than 1, thoracic liver position, and aberrant stomach position have been found to be associated with delayed time to resolution of pulmonary hypertension and may be used to identify fetuses at high risk of persistent pulmonary hypertension. [29]

(See the image below.)

Ultrasonogram of a right-sided congenital diaphrag Ultrasonogram of a right-sided congenital diaphragmatic hernia shows the liver herniating through the defect.

Romiti et al proposed a new CDH ultrasonographic marker in fetuses called the mediastinal shift angle. In their report, on the same ultrasound images commonly used for lung-to-head ratio (LHR) measurement, a landmark line was drawn from a point on the posterior face of the vertebral body, splitting it into 2 equal parts, to the midposterior surface of the sternum. Another landmark line was then traced from the same point of the vertebral body to touch tangentially the lateral wall of the right atrium. The angle between these 2 lines was used to quantify mediastinal shift and called the mediastinal shift angle (MSA). According to the researchers, statistical analysis confirmed an inverse correlation between MSA values and survival (P=.004), with the best cutoff value for MSA being 43.7°, which demonstrated the highest discriminatory power (sensitivity 63%; specificity 93.75%). [31]

Corsini et al reported that the pattern of lung ultrasound for CDH diagnosis in infants with respiratory distress includes partial absence of the hyperechoic line representing the normal diaphragmatic profile, partial absence of the pleural line in the affected hemithorax, absence of A lines in the affected area, presence of multi-layered area with hyperechoic contents in motion (normal gut), and possible presence of parenchymatous organs inside the thorax (ie, liver or spleen). [32]

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