Over the years I’ve seen a number of trauma professionals, both surgeons and emergency physicians, order liver transaminases (SGOT, SGPT) and bilirubin in patients with liver laceration. I’ve never been clear on why, so I decided to check it out. As it turns out, this is another one of those “old habits die hard” phenomena.

Liver lacerations, by definition, are disruptions of the liver parenchyma. Liver tissue and bile ducts of various size are both injured. Is it reasonable to expect that liver function tests would be elevated? A review of the literature follows the typical pattern. Old studies with very few patients.

From personal hands-on observations, the liver tissue itself tears easily, but the ducts are a lot tougher. It is fairly common to see small, intact ducts bridging small tears in the substance of the liver. However, larger injuries can certainly disrupt major ducts, leading to major problems. But I’ve never seen obstructive problems develop from this injury.

A number of papers (very small, retrospective series) have shown that transaminases can rise with liver laceration. However, they do not rise reliably enough to be a good predictor of either having an injury, or the degree of injury. Similarly, bilirubin can be elevated, but usually not as a direct result of the injury. The most common causes are breakdown of transfused or extravasated blood, or from critical care issues like sepsis, infection, and shock.

Bottom line: Don’t bother to get liver function tests in patients with known or suspected injury. Only a CT scan can help you find and/or grade the injury. And never blame an elevated bilirubin on the injury. Start searching for other causes, because they will end up being much more clinically significant.

References:

• Evaluation of liver function tests in screening for intra-abdominal injuries. Ann Emerg Med 20(8):838-841, 1991.
• Markers for occult liver injury in cases of physical abuse in children. Pediatrics 89(2):274-278.
• Combination of white blood cell count with liver enzymes in the diagnosis of blunt liver laceration. Am J Emerg Med 28(9):1024-1029, 2010.

The July newsletter is now available! Click the image below or the link at the bottom to download. This month’s topic is x-rays. 

In this issue you’ll find articles on:

• CT scan images simplified
• CT scans for rib fractures?
• A trick for finding rib fractures on chest xray
• Futility of the lateral view for pneumothorax
• Do you really need to repeat that xray?
• How often are outside images repeated?
• Repeat imaging: what good is it?

Subscribers had the newsletter emailed to them over the weekend. If you want to subscribe (and download back issues), click here.

Download the newsletter here!

The pedestrian struck by a car presents challenges to trauma professionals for a number of reasons. Due to the size mismatch between the two, serious injuries are fairly common. And unfortunately, many injuries are occult, so it’s easy to dismiss patients who may be hiding serious problems.

The National Highway and Traffic Safety Administration (NHTSA) recently published its Traffic Safety Facts report for 2011. This 232 page tome contains a wealth of interesting and thought-provoking data. One of the more interesting tidbits that caught my eye had to do with pedestrians struck by cars.

Most normal people do not get hit by cars. There is nearly always some additional factor that allows this to occur:

• Don’t understand cars – this is a typical reason for small children, and I’ve also seen foreign visitors from countries with little auto traffic fall victim to this one. The developmentally disabled also fall into this category.
• Not paying attention – this category is growing rapidly due to smart phone use
• Can’t clear the intersection in time – this one gets the elderly. Due to physical constraints, they can’t move fast enough (4 ft/sec for most intersections) to get across in time
• Intoxicated – this basically puts an adult back into the first category above. These incidents tend to be clustered around bars, and the numbers peak at night, typically from midnight to 3am.

The NHTSA report has always detailed the age breakdown of pedestrians struck, but now they are reporting the number of “impaired walkers” as well.

• Overall, death by motor vehicle (occupants and pedestrians) involved alcohol 31% of the time (!!)
• 4,432 pedestrians were killed and about 69,000 were injured
• About one third of pedestrians killed tested positive for alcohol, and most were legally intoxicated!
• 14% of the nonintoxicated pedestrians were struck by an intoxicated driver vs 19% of intoxicated pedestrians

Bottom line: There are many reasons for getting hit by a car, and being intoxicated is an entirely avoidable one. These patients can be seriously injured, so don’t just shrug off complaints as being due to intoxication. Additional prevention efforts should be developed using the interesting patterns outlined in the NHTSA report.

Reference: NHTSA Traffic Safety Facts 2011