From the Guidelines
The sensitivity of ultrasound for detecting injuries in abdominal blunt trauma is approximately 79-83%, with a specificity of 95-100%, as reported in the most recent and highest quality studies 1.
Key Findings
- The sensitivity of ultrasound in detecting intra-abdominal injuries ranges from 79% to 88% in different studies 1.
- The specificity of ultrasound is high, ranging from 94% to 100% in various studies 1.
- Ultrasound is most sensitive for detecting free fluid in the peritoneal cavity, but less sensitive for identifying specific organ injuries.
- The diagnostic accuracy of bedside ultrasound may vary depending on ultrasonographer skill and equipment 1.
Limitations and Considerations
- Ultrasound has limitations, including the inability to identify the etiology of free fluid or detect injuries with minimal fluid accumulation 1.
- Serial ultrasounds can be helpful in patients with blunt abdominal trauma, as initial results may be negative due to delayed fluid accumulation 1.
- A negative ultrasound result in hemodynamically unstable patients does not preclude the need for further diagnostic testing 1.
Clinical Implications
- Ultrasound remains a valuable tool in trauma assessment due to its non-invasive nature, portability, and speed of examination 1.
- For hemodynamically unstable patients with positive ultrasound results, immediate surgical intervention may be warranted, while stable patients with negative results may require additional imaging such as CT scan for comprehensive evaluation 1.
From the Research
Sensitivity of Abdominal Blunt Trauma Ultrasound
- The sensitivity of Focused Assessment with Sonography for Trauma (FAST) in detecting free fluid in blunt trauma abdomen was found to be 77.27% when compared with contrast-enhanced computed tomography (CECT) 2.
- When compared with surgical findings, the sensitivity of FAST was 94.44% 2.
- The overall sensitivity of FAST for detecting free fluid in the abdomen was 80.43% 2.
- A study on sonography as the primary screening method in evaluating blunt abdominal trauma found that ultrasound had a high negative predictive value of 96% 3.
- Another study found that a large intraperitoneal fluid accumulation on ultrasonography in combination with unstable vital signs was sensitive for determining the need for exploratory laparotomy in patients presenting with blunt trauma, with a sensitivity of 89% 4.
- However, ultrasonography was found to miss 28% of lesions in blunt trauma patients compared to CT, including intestinal lesions that needed laparotomy 5.
- The usefulness index of ultrasound for detecting lesions of the kidneys, free intraperitoneal fluid, the liver, the spleen, and intestines was found to be 1,0.76,0.72,0.69, and 0, respectively 5.
Comparison with Other Diagnostic Modalities
- CT is still considered the imaging modality of choice for detecting intra-abdominal lesions in stable patients with blunt abdominal trauma 5.
- Ultrasound can be used as an initial screening method for blunt abdominal trauma, but its limitations include dependence on operator skill and technique, poor image quality in certain patients, and limited visualization of the retroperitoneum 6.