Diaphragmatic rupture

Last revised by Liz Silverstone on 12 Jun 2024

Diaphragmatic rupture or injury often results from blunt abdominal trauma. The mechanism of injury is typically a motor-vehicle collision.

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Given that the most common mechanism is motor vehicle collisions, it is perhaps unsurprising that young men are most frequently affected. The estimated incidence is ~4.5% (range 0.8-8%) of patients who sustain blunt abdominal or lower thoracic trauma 1,2.

It is frequently not recognised at the time of trauma and the interval between injury and the onset of symptoms. However, if the diagnosis is not made in the first 4 hours, it may be undiagnosed for months or years. 

Two basic blunt mechanisms are accepted based on the direction of applied force: lateral impaction and anterior-posterior (AP) impaction 10. Other possible mechanisms are direct injury from adjacent rib fractures and indirect injury from rapid diaphragm contraction against a closed glottis 10. The left hemidiaphragm is involved three times more frequently than the right, possibly because the liver has a buffering effect.

The most common site of rupture is the posterolateral aspect of the hemidiaphragm between the lumbar and intercostal muscle slips, where the diaphragm is the weakest 10. Ruptures occur radially and most are >10 cm in length 4, 10. Less common sites are the central tendon and costal attachments 10.

The most commonly herniated viscera are the stomach and colon 9. It is rare to see rupture of the diaphragm without evidence of abdominal trauma, although this may be seen in the context of iatrogenic injury.

Penetrating injury is usually the result of gunshot wounds or stabbing. As expected there is almost always associated injuries of the adjacent thoracic and abdominal organs. Penetrating injuries are usually smaller that those caused by blunt trauma, and often only the site of the projectile or knife. Penetrating injuries are more common on the left, proposed to be due to right-handed perpetrators using their dominant hand 10.

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Specific diagnostic findings of diaphragmatic rupture on chest radiographs may not be seen in up to 50% of cases 1. However, the following signs are helpful in making the diagnosis:

  • inability to trace the normal hemidiaphragm contour

  • intrathoracic herniation of a hollow viscus (stomach, colon, small bowel) with or without focal constriction of the viscus at the site of the tear (collar sign)

  • if large, the positive mass effect may cause a contralateral mediastinal shift

  • visualisation of a nasogastric tube above the hemidiaphragm on the left side

  • left hemidiaphragm much higher than the right

  • mediastinal shift

  • associated chest injuries such as rib fractures, haemothorax, pneumothorax and pulmonary contusions

Plain radiographs have low sensitivity 10:

  • 27%–62% for left hemidiaphragm injuries

  • 17% for right hemidiaphragm injuries

CT is the best imaging modality for blunt diaphragm injury identification with a reported sensitivity of 56%–87% and specificity of 75%–100% 10.

Direct discontinuity of the hemidiaphragm has a sensitivity of 17%–80% and specificity of 90%–100% 10. It may be seen with or without intrathoracic herniation of abdominal contents: the stomach and colon most commonly on the left side and the liver is the most common viscus to herniate on the right side.

Other signs of diaphragmatic rupture include:

  • the collar sign (or hourglass sign)  3: a waist-like constriction of the herniating hollow viscus from the abdomen into the chest at the site of the diaphragmatic tear, which is classical for diaphragmatic rupture

  • the dependent viscera sign: when a patient with a ruptured diaphragm lies supine at CT examination, the herniated viscera (bowel or solid organs) are no longer supported posteriorly by the injured diaphragm and fall to a dependent position against the posterior ribs

  • segmental non-recognition of the diaphragm

  • focal diaphragmatic thickening

  • thoracic fluid abutting the abdominal viscera

Indirect features include:

Imaging mimics of diaphragmatic injury include:

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