From the Guidelines
For suspected lower rib fractures, a chest X-ray (posteroanterior and lateral views) is the recommended initial imaging study. This recommendation is based on the American College of Radiology Appropriateness Criteria 1, which suggest that a standard posteroanterior chest radiograph should be the initial diagnostic test for detection of rib fractures. Although chest X-rays have limited sensitivity for rib fractures, detecting only about 50% of fractures 1, they are usually sufficient for the diagnosis of rib fractures, and further imaging is generally not appropriate as there is little data that undiagnosed isolated rib fractures after minor blunt trauma affect management or outcomes 1.
If clinical suspicion remains high despite negative X-rays or if complications are suspected, a CT scan of the chest should be ordered as it offers superior sensitivity (up to 95%) for detecting rib fractures and can better visualize associated injuries 1. The presence and number of rib fractures, and the degree of displacement of the fractures, may carry prognostic significance, and detection of rib fractures by CT may be indicated under certain circumstances, especially if severe injury is suspected 1. Ultrasound may be considered as an alternative, particularly in pregnant patients or children to minimize radiation exposure, though it is operator-dependent and less standardized. MRI is rarely needed for isolated rib fractures but may be useful when evaluating associated soft tissue injuries.
The imaging choice should be guided by clinical presentation, with particular attention to potential complications like pneumothorax, hemothorax, or organ injury that may accompany lower rib fractures, especially fractures of ribs 9-12 which can be associated with abdominal organ injuries 1. In patients with multiple injuries and lower rib fractures, contrast-enhanced CT might be indicated even in the setting of a normal clinical examination 1. The most recent and highest quality study 1 supports the use of contrast-enhanced CT of the chest as the preferred imaging workup of suspected chest trauma, as it is more sensitive and specific for chest trauma than conventional radiographs.
From the Research
Imaging for Lower Suspected Rib Fracture
- The American College of Radiology Appropriateness Criteria recommend a standard posteroanterior chest radiograph as the initial, and often the only, imaging test required in patients with suspected rib fracture after minor trauma 2.
- However, chest CT is more sensitive than a chest X-ray (CXR) in diagnosing rib fractures, and can identify additional fractures that may not be visible on CXR 3, 4.
- The presence of rib fractures on CXR or CT can be associated with significant morbidity and mortality, and the number of fractured ribs can increase the risk of complications such as pneumothorax, hemothorax, and pulmonary contusion 3, 4, 5.
- In elderly fall-injured patients, CT-diagnosed rib fractures with a normal CXR were associated with increased hospital admissions, but not with increased procedural interventions, ICU admission, hospital/ICU LOS, or mortality 6.
- The use of CT scanning can provide more detailed information about the location and number of rib fractures, which can be useful in guiding treatment and management decisions 3, 4, 5.
Factors to Consider
- The sensitivity and specificity of CXR and CT scans for diagnosing rib fractures, with CXR having a sensitivity of 40% and specificity of 99% compared to CT 6.
- The association between the number of rib fractures and the risk of complications, with an increased number of fractures increasing the risk of morbidity and mortality 3, 4, 5.
- The importance of considering other factors, such as the patient's age, mechanism of injury, and presence of other injuries, when interpreting imaging results and guiding treatment decisions 2, 3, 4, 5, 6.