Author: Dr. Shayna Adams
Background: The paper validates a prediction rule that aims to identify kiddos with intra-abdominal injuries after blunt trauma. The prediction rule was derived from a previous study that looked at about a thousand children and found six factors to be related to intra-abdominal injury. In order to trigger the prediction rule, the kiddo had to have at least one of the following six factors:
- ↓ BP
- Abdominal tenderness
- Femur fracture
- ↑ LFTs
- Microscopic hematuria
- HCT < 30%
Study Question: How good is this prediction rule at identifying kids with intra-abdominal injuries?
Design: A prospective observational cohort study that took place at a single level 1 trauma center over three years. The study population were children under the age of 18 who suffered some sort of blunt torso trauma. They all underwent some sort of definitive diagnostic test, such as a CT, DPL, or surgery.
Results: When the prediction tool was applied, 8 out of the 157 kids with intra-abdominal injuries were missed. But when you look at those kids, 7 were just observed and did fine. One patient, however, underwent a diagnostic laparotomy which identified a serosal tear and mesenteric hematoma but ultimately did not require any intervention.
Discussion: The 8 kids with injuries not identified by the prediction rule had hard signs that would have convinced most docs to scan them. They had tenderness over their costal margins, a positive seatbelt sign, altered mental status (low GCS), or elevated LFTs not above the rule’s threshold. This is why I don’t like rules. It’s not because I have no respect for authority, contrary to what my mum thinks. It’s because I believe in using my sensibilities. Attendings around here call it “gestalt.” I call it The Force. Tomato, toe-mah-toe.
Limitations of this study include a lack of external validity since it was conducted at a single site. A decent amount of patients (15%) were also excluded due to lack of data (such as specific labs like LFTs). Furthermore, there was no clear cut definition of blunt torso trauma. There was no risk stratification described in the paper so Sally who tripped on her shoelace, hit her tummy on the carpet and has an owie may have been in the same category as Genevieve who got hit by a car while she was playing hop-scotch along the freeway.
The main takeaways I got from reading this paper was that, first and foremost, rely on your primary and secondary survey. If the patient is hemodynamically unstable, altered, or have significant injuries, consider an intra-abdominal injury and maybe just go ahead and them. However, if they are stable enough to await bloodwork and a urinalysis, then you have time to consider clinical prediction rules to potentially reduce radiation exposure. At that point, if there is a lab abnormality such as elevated LFTs or hematuria, have a low suspicion to act on it and pursue more of a work-up or intervention.
Take Away: If the kid is clinically stable and you have time to wait for blood and urine tests, remember why you ordered those tests in the first place and have a low suspicion to act on abnormal results as they may be a sign of intra-abdominal injury. Otherwise, if Sally looks good on exam and on paper, maybe you can save her a trip to the CT scanner.
Reference: Holmes JF, Mao A, Awasthi S, et al. Validation of a prediction rule for the identification of children with intra-abdominal injuries after blunt torso trauma. Ann Emerg Med 2009; 54:528.