This study aimed to determine whether routine urinalysis may serve as a tool in discriminating between acute appendicitis and perforated appendicitis in children.

We prospectively collected 357 patients with clinically suspected acute appendicitis. Urinalysis was performed in patients with clinically suspected acute appendicitis before surgical intervention. Routine urinalysis is composed of 2 examinations: chemical tests for abnormal chemical constituents and microscopic tests for abnormal insoluble constituents. Receiver operating characteristic curves for urine white blood cell (WBC) counts and urine red blood cell (RBC) counts in distinguishing between patients with simple appendicitis and patients with perforated appendicitis were also analyzed.

Urine ketone bodies, leukocyte esterase, specific gravity, pH, WBC, and RBC counts were all significant parameters among patients with normal appendices, simple appendicitis, and perforated appendicitis (all P < .05). Based on multivariate logistic regression analysis, positive urine ketone bodies and nitrate were significant parameters in predicting perforated appendicitis (P = .002 and P = .008, respectively). According to the results of receiver operating characteristic curves, the appropriate cutoff values were 2.0/high-power field for urine RBC counts and 4.0/high-power field for urine WBC counts in predicting perforated appendicitis in children.

Routine urinalysis may serve to aid in discriminating between simple and perforated appendicitis. Clinically, we believe that these urine parameters may aid primary emergency physicians with decision making in patients with clinically suspected appendicitis.