Background: Abdominal abrasions and contusions from seatbelts in a motor vehicle collision (MVC) are aptly named “abdominal seatbelt signs (ASBS).” This finding correlates to higher risk of intra-abdominal injury (IAI). Patients with ASBS are routinely admitted for observation and serial abdominal exams, even with negative computed tomography (CT) of the abdomen/pelvis (A/P), due to concern for occult bowel or mesentery injury. We created a database of patients with ASBS to determine if admission for serial exams for isolated ASBS is justified. We hypothesized near 100% sensitivity of CT for clinically significant IAI, and that a normal CT allowed for safe discharge in patients with no other injuries warranting admission.
Materials and Methods: This is an IRB approved, retrospective study from a Level 1 Trauma Center from 2013-2015. We queried all 2,338 charts from patients in MVC’s with any abdominal complaints or diagnoses to detect all patients with ASBS. These charts were further reviewed and many data points were recorded in a secure, encrypted online database (REDCap).
Results: We detected 433 patients with recorded physical exam demonstrating ASBS (172 abrasion, 254 contusion, 73 both, 76 unknown). The incidence of IAI in the entire cohort was 56%. Among patients with abrasion-only ASBS (n= 99), 38% had a positive CT A/P, and 19% had exploratory laparotomies. Contusion-only ASBS (n=181) patients had a positive CT A/P in 57% of cases, with 10% undergoing exploratory laparotomy. Of all ASBS patients, 178 had negative CT A/P, and 96 % of those were admitted. Of those admitted, 114 had other injuries warranting admission, and 58 were admitted only for serial exams. Thirty had repeat CT A/P, and no new IAIs were discovered. None of the 178 patients had surgery for delayed IAI. The sensitivity of initial CT A/P was 100%, specificity 100%, NPV was 100%, and PPV was 99%. No patient with a CT demonstrating only free fluid (n=12) and/or soft tissue injury (n=55) had delayed IAI diagnosis or surgery. None of the patients who returned within 30 days were diagnosed with new IAI.
Conclusion: It is reasonable to discharge a patient with ASBS with a negative initial CT A/P or CT A/P positive only for free fluid and/or soft tissue injury. The ASBS predicts a significant amount of IAI, therefore the threshold of CT A/P should be low.