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Source: Ochsner MG, et al. Significance of minimal or no intraperitoneal fluid visible on CT scan associated with blunt liver and splenic injuries: A multicenter analysis. J Trauma 2000;49:505-510.
In many centers, bedside ultrasound (u/s) has become a valuable tool in the emergency assessment of the injured patient. It is generally accepted that, in experienced hands, U/S will detect fluid
collections of 250 mL or more.1 The purpose of this study was to describe the incidence and clinical importance of liver and spleen injuries with minimal (< 250 mL) or no free intraperitoneal fluid visible on CT scan.
All patients with liver and spleen injuries were identified retrospectively using medical records and CT scan review. Study inclusion criteria were liver and spleen injury, identification by CT scan, and minimal or no free fluid on CT scan. Minimal fluid was defined as less than 250 mL, and was calculated using Knudson’s quantification scale.2 Nine hundred thirty-eight patients with liver and spleen injury were identified. Two hundred sixty-seven (28%) met inclusion criteria and had minimal or no free fluid on CT. One hundred sixty-one had injury to the spleen and 125 had injury to the liver. Ninety-seven percent of included patients were managed nonoperatively; while eight patients (3%) required operative intervention for bleeding. There were no deaths or major complications. Compared to the liver, the spleen was significantly more likely to bleed (P = 0.01), but the grade of splenic injury was not related to hemorrhage risk.
A growing number of studies document the excellent sensitivity, specificity, and accuracy of U/S as a screening tool to identify intra-abdominal hemorrhage.1,3,4 As U/S gains acceptance, algorithms for its use must be developed. Clinicians should develop a clear understanding of what to do with both positive and negative scans. Currently, there are two accepted clinical scenarios for which the results of the U/S should trigger a clear response:
• In the clinically unstable blunt trauma patient, a positive U/S should prompt immediate exploratory laparotomy without further diagnostic testing.
• In the clinically stable blunt trauma patient with a positive U/S, CT scanning of the abdomen should be performed to further define specific injuries.
Knowing what to do with a negative U/S is a bit trickier, but no less important. It is this author’s opinion that:
• In the clinically unstable blunt trauma patient, a negative U/S should be followed by a diagnostic peritoneal aspirate.
• In the clinically stable blunt trauma patient with a significant mechanism of injury, a negative U/S should be followed by an abdominal CT scan or an appropriate period of clinical observation. Serial ultrasounds are another option in this setting.
This is not an U/S study. The retrospective design does have inherent weaknesses. Nonetheless, the results do remind us that a negative U/S does not always rule out significant injury. Studies like this one should stimulate future research in trauma U/S and help with the development of clinical pathways. As we continue to adopt U/S (or any other new technology) into the practice of emergency medicine, we must understand what it can and cannot do.
1. Fernandez L, et al. Ultrasound in blunt trauma. J Trauma 1998;45:841-848.
2. Knudson MM, et al. Nonoperative management of blunt liver injuries in adults: The need for continued surveillance. J Trauma 1990;30:1494-1500.
3. McKenney MG, et al. Can surgeons evaluate emergency ultrasound scans for blunt abdominal trauma?
J Trauma 1998;44:649-653.
4. Wherrett LJ, et al. Hypotension after blunt abdominal trauma: The role of emergent abdominal sonography in surgical triage. J Trauma 1996;41:815-820.