Presence of Microscopic Hematuria Does Not Predict Clinically Important Intra-Abdominal Injury in Children

Objective: Screening for blunt intra-abdominal injury in children often includes directed laboratory evaluation that guides need for computed tomography. We sought to evaluate the use of urinalysis in identifying patients with clinically important intraabdominal injury (ci-IAI).

Methods: A retrospective chart review was performed for all patients less than 18 years who presented with blunt mechanisms at a level I trauma center between 2016 and 2019. Exclusion criteria included transfer from an outside facility, physical abuse, and death within thirty minutes of arrival. Demographics, physical exam findings, serum chemistries, urinalysis, and imaging were reviewed. Clinically important intraabdominal injury was defined as injury requiring ≥2 nights admission, blood transfusion, angiography with embolization, or therapeutic surgery.

Results: Two hundred forty patients were identified. One hundred sixty-five had a completed urinalysis. For all patients an abnormal chemistry panel and abnormal physical exam had a sensitivity of 88.9% and a negative predictive value of 99.3%. Nine patients had a ci-IAI. Patients with a ci-IAI were more likely to have abdominal pain, tenderness on exam, and elevated hepatic enzymes. When patients were stratified by the presence of an abnormal chemistry or physical exam with or without microscopic hematuria, urinalysis did not improve the ability to identify patients with a ci-IAI. In fact, presence of microscopic hematuria increased the rate of false positives by 12%.

Conclusions: Microscopic hematuria was not a useful marker for ci-IAI and may lead to falsely assuming a more serious injury.