Discriminatory power of 3.5 MHz convex and 7.5 MHz linear ultrasound probes for the imaging of traumatic splenic lesions: a feasibility study.

BACKGROUND: Ultrasound is a powerful tool for recognition of free fluid after blunt abdominal trauma, whereas its role for detection of organ lesions remains to be defined. The objective of this study was to determine the diagnostic value of different ultrasound transducers for the precise detection of visceral damage rather than its surrogates in case of splenic injury.
METHODS: After a standardized focused abdominal sonogram for trauma protocol to screen for hemoperitoneum, 37 slim, hemodynamically stable subjects with suspected torso trauma were investigated for the extent of parenchymal lesions of the spleen using a 3.5 MHz curved array and a 7.5 MHz linear device. Helical computed tomographic scanning was carried out as the reference standard in all cases.
RESULTS: Twenty patients presented splenic damage. The 7.5 MHz transducer showed higher accuracy than the lower frequency probe for the detection of tissue irregularities (difference in proportions, 16.2%; 95% confidence interval, -1.9%-33.5%). A similar trend was observed for 13 lacerations subsequently progressing to two-timed splenic rupture that required surgery (absolute risk reduction, 8.1%; 95% confidence interval, -7.6%-23.9%). With an observed prevalence of 54% for the presence of splenic injury, organ lacerations could be excluded more confidently using the linear probe (posttest probability, 16% vs. 36%).
CONCLUSION: In slim patients, higher frequency linear ultrasound probes can provide therapy-relevant information on the integrity of splenic parenchyma after blunt abdominal trauma.