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 aft er blunt abdominal trauma, whereas its role for detection of organ lesions remains to be defined. The objective of this study was to determine the dia gnostic 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 protoco l to screen for hemoperitoneum, 37 slim, hemodynamically stable subjects wi th suspected torso trauma were investigated for the extent of parenchymal l esions of the spleen using a 3.5 MHz curved array and a 7.5 MHz linear devi ce. 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 s howed higher accuracy than the lower frequency probe for the detection of t issue irregularities (difference in proportions, 16.2%; 95% confidence inte rval, -1.9%-33.5%), A similar trend was observed for 13 lacerations subsequ ently progressing to two-timed splenic rupture that required surgery (absol ute risk reduction, 8.1%; 95% confidence interval, -7.6%-23.9%). With an ob served prevalence of 54% for the presence of splenic injury, organ lacerati ons could be excluded more confidently using the linear probe (posttest pro bability, 16% vs, 36%), Conclusion: In slim patients, higher frequency linear ultrasound probes can provide therapy-relevant information on the integrity of splenic parenchym a after blunt abdominal trauma.