CAISS Thorax Injuries 4 — Questions and Answers
Question 1: In AIS coding, 'pulmonary laceration' differs from 'pulmonary contusion' primarily because:
- Lacerations only occur with penetrating trauma
- Lacerations involve a discrete tear in lung parenchyma (Correct answer)
- Contusions are always bilateral
- Lacerations require a higher energy mechanism
Correct answer: Lacerations involve a discrete tear in lung parenchyma
Pulmonary laceration involves a discrete parenchymal tear producing a pneumatocele or hematoma, while contusion is diffuse alveolar hemorrhage without structural disruption.
Question 2: Rib fractures involving ribs 1 or 2 are clinically significant because they indicate:
- Greater pain severity due to cartilage involvement
- High-energy mechanism with risk of great vessel injury (Correct answer)
- Higher likelihood of pneumothorax than lower rib fractures
- Automatic AIS 4 classification
Correct answer: High-energy mechanism with risk of great vessel injury
Fractures of the 1st and 2nd ribs require high energy and are associated with subclavian vessel, brachial plexus, and aortic arch injuries.
Question 3: A sternal fracture alone, without associated cardiac or vascular injury, is most commonly assigned an AIS code of:
- AIS 1
- AIS 2 (Correct answer)
- AIS 3
- AIS 4
Correct answer: AIS 2
An isolated sternal fracture without complications is coded AIS 2 (moderate), reflecting its moderate clinical significance without immediate life threat.
Question 4: The AIS 2015 revision introduced refinements to thoracic aortic injury coding primarily to better reflect:
- Mechanism of injury (blunt vs. penetrating)
- Injury location (ascending vs. descending)
- Injury grade based on imaging (intimal tear through transection) (Correct answer)
- Patient age and comorbidities
Correct answer: Injury grade based on imaging (intimal tear through transection)
The AIS 2015 revision aligned thoracic aortic injury codes with imaging-based grading (Grade I–IV), from intimal tear to complete transection.
Question 5: When coding multiple rib fractures on the same side, the AIS severity increases with the number of ribs because:
- Each additional rib fracture adds 0.5 to the AIS score
- More fractures correlate with greater respiratory compromise and mortality risk (Correct answer)
- Multiple fractures on one side always indicate flail chest
- AIS uses a multiplicative formula for ipsilateral rib fractures
Correct answer: More fractures correlate with greater respiratory compromise and mortality risk
More rib fractures on the same side indicate higher-energy trauma and greater respiratory impairment, which is reflected in a higher AIS severity code.
Question 6: A penetrating cardiac injury to the right ventricle is generally associated with a better prognosis than left ventricular injury because:
- Right ventricular walls are thicker
- Right ventricular pressures are lower, reducing hemorrhage rate (Correct answer)
- Right ventricular injuries are always coded as AIS 3
- Penetrating injuries rarely reach the left ventricle
Correct answer: Right ventricular pressures are lower, reducing hemorrhage rate
The right ventricle operates at lower pressures, so penetrating injuries bleed less rapidly, allowing more time for surgical intervention.
Question 7: In the context of AIS, 'hemopneumothorax' is coded as:
- Two separate codes — one for hemothorax and one for pneumothorax (Correct answer)
- A single combined code reflecting the most severe component
- Always as AIS 3 regardless of volume
- Under the cardiovascular substructure code
Correct answer: Two separate codes — one for hemothorax and one for pneumothorax
When both hemothorax and pneumothorax are present, AIS coding assigns separate codes for each component injury rather than a single combined code.
CAISS Thorax Injuries 4
In AIS coding, 'pulmonary laceration' differs from 'pulmonary contusion' primarily because: