We see seat belt signs at our trauma center with some regularity. There are plenty of papers out there that detail the injuries that occur and the need for a low threshold for surgically exploring these patients. I have not been able to find specific management guidelines, and want to share some tidbits I have learned over the years. Yes, this is based on anecdotal experience, but it’s the best we have right now.

Tips for surgeons:

• Common injuries involve the terminal ileum, proximal jejunum, and sigmoid colon. My observation is that location in the car is associated with the injury location, probably because of the location of the seat belt buckle. In the US, drivers buckle on the right, and I’ve seen more terminal ileum and buckethandle injuries in this group. Front seat passengers buckle on the left, and I tend to see proximal jejunum and sigmoid injuries more often in them.
• Seat belt sign on physical exam requires abdominal CT for evaluation, regardless of age. The high incidence of significant injury mandates this test.
• Seat belt sign plus any anomaly on CT requires evaluation in the OR. The only exception would be a patient with minimal fluid only in the pelvis with an unremarkable abdominal exam. But I would watch them like a hawk.
• In patients who cannot be examined clinically (e.g. severe TBI), a rising WBC count or lactate beginning on day 2 after adequate resuscitation should prompt a trip to the OR. This is an indirect method for detecting injured bowel or mesentery.
• Laparoscopy may be used in patients with equivocal findings. Excessive blood, bile tinged fluid, succus, or lots of fibrin deposits on the bowel should prompt conversion to laparotomy. Tip: place all ports distant to the seat belt mark. The soft tissues are frequently disrupted, and gas may leak into this pocket prohibiting good insufflation of the peritoneal cavity.
• If in doubt, open the abdomen. It’s bad form to put in the scope, see something odd, and walk away. Remember, any abnormal finding after trauma is related to trauma until proven otherwise. It’s almost never pre-existing disease.

Related posts:

• The seat belt sign
• Seat belt sign: 20 years ago
• Bucket handle injury from seat belts

Centers that take care of blunt trauma are familiar with the spectrum on injury that is directly attributable to seat belt use. Although proper restraint significantly decreases mortality and serious head injury, seat belts can cause visceral injury, especially to small bowel.

Lap belt use has been associated with Chance fracture (flexion distraction injury to the lumbar spine) since 1982. The association between seat belts and intra-abdominal injury, especially with an obvious “seat belt sign” was first described in 1987. 

Twenty years ago, orthopedic surgeons in Manitoba finally put two and two together and reported a series of 7 cases of Chance fractures. They noted that 6 of the fractures were associated with restraint use. Seat belt sign was also present in 5 of the 6 patients with fractures and three of the six had bowel injuries.

The authors noted that many provinces were mandating seatbelt use at the time, and they predicted that the number of Chance fractures, seat belt signs and hollow viscus injuries would increase. On the positive side, the number of deaths and serious head injuries would be expected to decline.

Although this was a small series, it finally cemented the unusual Chance fracture, seat belt sign, and bowel injury after motor vehicle trauma.

Reference: Pediatric Chance Fractures: Association with Intra-abdominal Injuries and Seatbelt Use. Reid et al. J Trauma 30(4) 384-91, 1990.

We take for granted that the so-called seatbelt sign is a harbinger of bad things in the abdomen. One of the first papers on this topic appeared in the February 1990 issue of the Journal of Trauma, entitled “Intra-abdominal Seatbelt Injury.”

The paper presents 8 cases who presented to the ED with a seatbelt sign after a motor vehicle crash. They found that serious injuries to the bowel and mesentery might be present without early symptoms or physical signs, and that CT scan and peritoneal lavage were not fully reliable in finding the injuries. Their conclusion was that the always wise “high index of suspicion” should be used in these patients.

Current day thinking has not changed much. During the last two decades, sentiment has swung from always operating based on these finding to being more selective. We recommend using good judgment. Seatbelt sign should always arouse a healthy suspicion for injury. A CT scan is now mandatory. If anything unusual is found (free fluid, bowel wall or mesenteric thickening or stranding) then a trip to the OR is indicated. Small bowel injuries may not become symptomatic for 12-72 hours, increasing the eventual complication rate if treatment is delayed.