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How Accurate Is CT for Hollow Viscus Injury After GSW?

August 16, 2022

Written by Sam Parnell

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Contrast enhanced CT can help predict the risk of hollow viscus injury after thoracoabdominal gunshot wounds. Specifically, there is low probability of hollow viscus injury in the absence of abdominal free fluid, focal gastrointestinal wall thickness, or fat stranding on CT.

Why does this matter?
Patients with penetrating abdominal injuries from gunshot wounds are at high risk for both solid organ and hollow viscus injuries (HVI). Historically, most of these patients were managed with exploratory laparotomy. However, CT is being utilized more frequently in stable patients to determine the need for operative vs non-operative management. We know that CT is helpful in determining solid organ injury, but what about the accuracy of CT for hollow viscus injury?

Hollow viscus and the donut of truth – now playing at an ED near you…
This was a single-center, retrospective, cohort study at a Level 1 trauma center from January 2015 to April 2019. Patients 18 years or older who had GSW to the thoracoabdominal region were included. Patients without indications for emergent laparotomy (hemodynamic instability, peritonitis, or unevaluable patients) were cared for with selective non-operative management (SNOM). Contrast enhanced abdominal CT was obtained after primary and secondary survey for all patients managed with the SNOM protocol.

There were 212 patients in the study with GSW to the thoracoabdominal region managed with the SNOM protocol. Overall, 158 patients (74.5%) were successfully managed nonoperatively, and 54 patients (25.5%) had a laparotomy. In total, 43 out of the 54 patients who had a laparotomy were diagnosed with HVI. HVI was found in the colon (60.5%), small bowel (58.1%), stomach (23.2%), and rectum (2.3%). Furthermore, 23 patients (42.6%) with HVI also had solid organ injury.

CT findings suggestive of HVI included abdominal free fluid, diffuse free air, focal gastrointestinal wall thickness, wall irregularity, abnormal wall enhancement, fat stranding, and mural defect. Abdominal free fluid and fat stranding had the highest sensitivity (100%, 95%CI 92-100; 91%, 95%CI 78-97, respectively), and abdominal free fluid also had the highest NPV (100%, 95%CI 95-100). Mural defect on CT had the highest specificity (99%, 95%CI 97-100) and PPV (93%, 95%CI 64-99). The NPV for each of the CT findings investigated were greater than 85%, meaning that the probability of HVI was very low if none of these CT criteria were present.

External validation studies are needed to verify the accuracy of CT for HVI. However, based on these results, it appears that contrast enhanced CT can be quite useful in the evaluation of HVI for stable patients with thoracoabdominal GSW.

Source
Diagnostic accuracy of computed tomography findings for hollow viscus injuries following thoracoabdominal gunshot wounds. J Trauma Acute Care Surg. 2022 Jul 15. doi: 10.1097/TA.0000000000003743. Online ahead of print.

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