Diaphragmatic rupture

CT semiotics of diaphragmatic rupture

Detecting a rupture on standard tomograms can be extremely difficult. Reliable diagnosis requires multiplanar reconstructions to reveal several specific patterns:

• «Absent diaphragm» sign (absent diaphragm sign) — direct visualization of the anatomical defect of the dome.
• «Dangling diaphragm» sign (dangling diaphragm sign) — the edges of the ruptured muscle tissue curl inward into the thoracic or abdominal cavity.
• «Dependent viscera» sign (dependent viscera sign) — the liver, stomach, or bowel loops herniate through the defect, lose support, and lie closely against the posterior ribs.
• «Thick crus» sign (thick crus sign) — local thickening of the diaphragmatic crus on the side of the injury.
• «Collar» sign (collar sign) — marked compression (constriction) of the stomach or intestine within the narrow hernia orifice.

When the rupture is localized on the right (on the side of the liver), specific signs may be observed:

• «Hump» sign (hump sign) — mushroom-like protrusion of the liver into the right hemithorax, with the parenchyma compressed by the edges of the rupture.
• «Band» sign (band sign) — a linear lucency passing through the liver tissue along the edges of the ruptured hemidiaphragm.

In penetrating injuries, CT helps visualize the wound tract itself (knife track or bullet trajectory) and detect active arterial contrast extravasation.

Clinical features and delayed diagnosis

Diaphragmatic injury is often masked by severe polytrauma, leading to late diagnosis. The typical clinical and radiological picture over time is as follows:

1. Acute period (immediately after trauma): supine chest radiographs show only indirect signs of trauma — multiple rib fractures, pleural effusion, and hazy opacification in the basal regions. The defect itself is not differentiated.
2. Apparent well-being (1 month later): the radiological picture may completely normalize, and the effusion resolves.
3. Manifestation (2 months and later): a large gas-containing structure (e.g., the stomach) suddenly appears in the hemithorax on the radiograph. This indicates that a diaphragmatic hernia has formed through the unhealed defect.

In such cases, a CT scan is mandatory for definitive confirmation and surgical planning.

Application of MRI

In the acute phase of trauma, performing an MRI is technically difficult and impractical. However, the method demonstrates its value in the latent phase.

The main advantage of magnetic resonance imaging is the ability to examine the diaphragm not only statically, but also dynamically (during respiratory movements). The main limitation of the method, as with CT, remains the inability to differentiate parts of the diaphragm in direct contact with the liver and spleen parenchyma.

Differential diagnosis: neoplasms

Pathological changes in the contours of the diaphragm are not always trauma-related. They must be distinguished from tumor processes, for which CT and MRI are also the most informative modalities.

• Primary tumors: extremely rare, originating from muscle, adipose, fibrous, or vascular tissue. They have distinct contours. When localized on the right, a large benign tumor can completely mimic dome relaxation or local eventration. Areas of calcification are sometimes detected in lipomas. Malignant forms are frequently accompanied by pleural effusion.
• Secondary involvement (invasion): occurs much more frequently as a result of direct invasion by malignant tumors of the lung, pleura, stomach, or pancreas.

Briefly: answers to topical questions

What else to study on this topic

• Technique of multiplanar reconstructions (MPR) in chest trauma
• Differential diagnosis of traumatic hernia and diaphragmatic eventration
• Specific CT signs of lung cancer invading the diaphragm
• Visualization of wound tracts in penetrating stab and gunshot wounds

Other topics in the «Chest Radiology» section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.