Written by Joshua Belfer
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In a cohort of children with blunt trauma, the presence of hematuria does not predict clinically important intraabdominal injury.
Urinalysis is probably not useful in screening
A retrospective chart review of 240 pediatric patients presenting with blunt mechanisms of injury at a single, level I pediatric trauma center assessed whether the addition of the urinalysis improved diagnostic accuracy for predicting clinically important intraabdominal injury (ci-IAI). Nine total patients were found to have a ci-IAI. The study found that of the 45 patients with microscopic hematuria (>3 RBC per high powered field), only 2 had a ci-IAI; of the 120 patients with a normal urinalysis, 3 had a ci-IAI.
Including the urinalysis, specifically microscopic hematuria, in the ci-IAI screening criteria (which typically includes abnormal physical exam findings and/or abnormal liver enzymes and lipase) decreased the specificity of screening. The false positive rate (i.e. any abnormal screening findings without a ci-IAI) increased with the addition of urinalysis to the screening criteria; the area under the ROC curve decreased from 0.681 (without urinalysis) to 0.619 (with the urinalysis).
Given the single center study, generalization of results is limited. While nearly 70% of patients had a urinalysis completed, the small sample size may suggest that inclusion of this remaining 30% (if possible) could have strengthened or weakened the results.
How will this change my practice?
There are several clinical prediction rules for intraabdominal injury in pediatric blunt trauma, some that include microscopic hematuria and some based on only clinical factors. In the absence of physical exam findings or lab abnormalities, this article suggests that microscopic hematuria alone should not lead clinicians to pursue abdominal imaging. Improving the false positive rate by not including the urinalysis into screening may help reduce the risk of ionizing radiation from unnecessary abdominal CT studies.
Source
Presence of Microscopic Hematuria Does Not Predict Clinically Important Intra-Abdominal Injury in Children. Pediatr Emerg Care. 2024 Jun 7. doi: 10.1097/PEC.0000000000003210. Epub ahead of print. PMID: 38849150.
