The "seat belt mark" sign: a call for increased vigilance among physicians treating victims of motor vehicle accidents.

The use of seat belts is shown to cause a specific pattern of internal injuries. Skin bruise corresponding to the site of the seat belt is known as the "seat belt mark" (SBM) sign and is associated with a high incidence of significant organ injuries. No study has yet defined the exact incidence of injuries requiring intervention at the presence of this sign. The objective of this study was to find the incidence of surgically correctable injuries in belted car occupants with a SBM sign and to define strategies of early detection and treatment of such injuries. The prospective study included consecutive patients involved in road traffic accidents who were admitted at an academic Level I trauma center. Of 650 car occupants, 410 (63%) were restrained and 77 (12%) had a SBM across the abdomen, chest or neck. The injuries of these 77 patients were compared with the injuries of belted patients without an SBM sign. Of patients with SBMs, 9 per cent had neck bruises, 32 per cent had chest bruises, 40 per cent had abdominal bruises, and 19 per cent had bruises in multiple sites. No significant neck injuries were detected. Three patients were found to have myocardial contusion, and 10 patients had intra-abdominal injuries (predominantly bowel and mesenteric lacerations) requiring laparotomy. There was a near 4-fold increase in thoracic trauma (22.5% versus 6%; P=0.01) and a near 8-fold increase in intra-abdominal trauma (23% versus 3%; P < 0.0001) between the groups of patients with and without SBMs. The presence of the SBM sign should alert the physician to the high likelihood of specific internal injuries. Routine laparotomy or mandatory evaluation by specific diagnostic tests is not justified; rather, a high index of suspicion with a low threshold for appropriate diagnostic evaluation and/or surgical exploration should be maintained for the optimal management of such patients.