The "seat belt sign" refers to a bruise in the distribution of a seat belt. Its presence should alert the clinician to look for several associated injuries that may not be immediately evident.


Seat belt sign: linear, band-like bruise across the abdomen, chest and/or neck


The risk of injury is increased if:

(1) the seat belt was misapplied

(2) the steering wheel or other object is struck


Sites of associated injuries:

(1) intestines

(2) bones

(3) cardiovascular

(4) other viscera


Intestinal injuries:

(1) rupture of jejunum

(2) rupture of descending and sigmoid colon

(3) mesenteric tears, which may compromise vascular supply to the intestines

(4) delayed formation of adhesions with obstruction

(5) delayed perforation associated with intramural hematomas



(1) lumbar spine L1-L3 ("chance" or transverse fracture through the vertebral body)

(2) sternum

(3) rib

(4) clavicle

(5) cervical spine


Cardiovascular injuries:

(1) thoracic aorta

(2) blunt injury to the carotid arteries

(3) blunt injury to the heart (myocardial contusion)

(4) thromboses in innominate, subclavian, carotid, vertebral or mesenteric arteries


Other viscera:

(1) rupture of the urinary bladder

(2) blunt trauma to the liver

(3) crush injury to the larynx


The presence of a seat belt sign alone does not warrant immediate investigation in all patients. However, the clinician should have a very low threshold for performing an investigation in the presence of a neurologic deficit, peritoneal irritation or other sign.


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