Classification and radiological signs of diaphragmatic hernias
According to classical radiological manifestations, there are two main types of this pathology with distinct imaging criteria:
- Bochdalek hernia (Bochdalek-type hernia). On a chest radiograph, this anomaly presents as multiple bowel loops located predominantly in the left hemithorax.
- Morgagni hernia (Morgagni-type hernia). Formed when there is a defect in the anterolateral diaphragm. Clinical symptoms typically manifest at an older age. On a plain chest radiograph, the pathology appears as a mass lesion located in the right cardiophrenic angle. Contrast-enhanced imaging is performed for definitive confirmation, allowing clear visualization of bowel loops entering directly into the hernia sac.
Differential diagnosis: Pulmonary sequestration
When opacities are detected in the lower hemithorax, the differential diagnosis must include pulmonary sequestration (Pulmonary Sequestration).
On a standard chest radiograph, it appears as a dense opacity in the left cardiophrenic sulcus. Computed tomography (CT) provides a detailed assessment of the blood supply to the affected area: in extralobar sequestration, massive systemic arterial blood supply originating directly from the aorta is reliably identified. Venous drainage occurs into the azygos venous system.
Congenital lobar emphysema
This condition requires careful imaging follow-up. Most commonly, the malformation affects the left upper lobe (in 42% of cases), while the right middle lobe is affected somewhat less frequently (35%).
The radiological appearance varies depending on the child's age:
- In the early postnatal period, the affected lobe appears radiopaque because it is completely filled with fetal lung fluid.
- On follow-up radiographs, characteristic hyperlucency of the lung field and overexpansion of the affected lobe are observed. Mediastinal shift of varying severity develops.
CT is used to exclude other causes of secondary hyperinflation, such as bronchial compression, vascular anomalies, or mediastinal masses. Management for asymptomatic patients consists of conservative observation (the degree of hyperinflation may decrease over time), whereas symptomatic infants require surgical resection of the affected lobe.
Bronchial atresia and agenesis-hypoplasia complex
Bronchial atresia (Bronchial Atresia) is a congenital anomaly characterized by obliteration of a lobar, segmental, or subsegmental bronchus (most commonly in the left upper lobe). Air enters the lung via collateral pathways, leading to the formation of an "air trap" and pulmonary hyperinflation with air retention on expiration. Mucus accumulates within the blind-ending atretic bronchus, forming a mucocele—a tubular, spherical, or branching opacity in the central regions. The disease may be asymptomatic, and infection of the isolated lung segment is extremely rare. Complications include marked mediastinal shift and collapse of ipsilateral lobes.
The differential diagnosis also includes pulmonary agenesis-hypoplasia complex. These conditions are grouped together due to overlapping imaging findings:
- Pulmonary agenesis (Pulmonary agenesis): complete absence of lung parenchyma, pulmonary vessels, and the bronchus itself.
- Pulmonary aplasia (Pulmonary aplasia): characterized by the presence of only a blind-ending rudimentary bronchus.
Briefly: answers to topical questions
What is the difference between intralobar and extralobar pulmonary sequestration?
Intralobar and extralobar pulmonary sequestrations differ in their anatomical location, age at presentation, and clinical manifestations.
| Sign | Intralobar sequestration | Extralobar sequestration (extralobar sequestration) |
|---|---|---|
| Localization | Lesion located within the lung parenchyma | In the mediastinum |
| Age of detection | Typically presents in adults | Detected in neonates |
| Features | Recurrent infectious complications | Associated with other malformations; venous drainage into the azygos system |
Through which collateral pathways does air enter the isolated lung segment in bronchial atresia?
In bronchial atresia, air enters the affected lung segment via collateral pathways, causing hyperinflation and the formation of an "air trap" (air trapping). In lung tissue, collateral ventilation occurs via interalveolar communications known as the pores of Kohn (pores of Kohn). They connect adjacent alveolar units and normally maintain lung expansion by equalizing air pressure between alveoli.
What are the types of diaphragmatic hernias?
The main types of diaphragmatic hernias include:
- Congenital hernias — include Bochdalek hernia (Bochdalek hernia), located posterolaterally on the left, and Morgagni hernia (Morgagni hernia), located anterolaterally on the right.
- Traumatic diaphragmatic hernias (Traumatic diaphragmatic hernias) — occur due to rupture of the diaphragm resulting from trauma.
- Retrosternal hernias — pass through the sternocostal triangles.
- Hiatal hernias (Hiatal hernias) — classified into 4 types: sliding (Sliding hernia), paraesophageal (Paraoesophageal), mixed (Mixed hiatal hernia), and intrathoracic stomach (Intrathoracic stomach).
For quick recall of the locations of common hernias, use the mnemonic: "Bochdalek is Bigger on the left, Morgagni is Massive on the right (in the cardiophrenic angle)."
Class and exam questions
What radiological signs are most characteristic of a Bochdalek hernia?
On a standard chest radiograph, multiple bowel loops are visualized, filling the left hemithorax.
What are the imaging features of a Morgagni hernia on contrast-enhanced studies?
Contrast-enhanced imaging clearly demonstrates bowel loops passing through the anterolateral diaphragmatic defect directly into the hernia sac. On a standard plain radiograph, this appears as a mass lesion in the right cardiophrenic angle.
How to differentiate congenital lobar emphysema in the first days of life?
In the early postnatal period, the affected lobe is fluid-filled, appearing radiopaque on radiographs. Hyperlucency and overexpansion develop only on subsequent follow-up imaging.
Why does hyperinflation occur in bronchial atresia despite airway obstruction?
Air enters the isolated lung segment not via the main bronchus, but through collateral pathways. During expiration, air cannot escape, creating an "air trap" and parenchymal overexpansion.
What else to study on this topic
- Anatomical prerequisites for the development of Bochdalek and Morgagni hernias
- Gastrointestinal contrast study technique in suspected diaphragmatic hernia
- CT angiography in the diagnosis of extralobar pulmonary sequestration
- Radiological signs of mucocele and its differential diagnosis
- Surgical management and indications for surgery in symptomatic congenital lobar emphysema
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