Background: Diagnosing appendicitis in children remains a challenge, and the role of urine dipstick is controversial. This study aimed to evaluate the association between abnormal urine dipstick results and appendicitis, particularly appendicitis severity and appendix position.
Methods: A prospective cohort study was conducted from 2017 to 2021 at a tertiary hospital in Sweden. Children aged ≤ 15 years with suspected appendicitis were included. Logistic regression was used to assess associations between abnormal urine dipstick results and sex, age, peritonitis, body temperature, C-reactive protein, complicated appendicitis, and appendix position.
Results: A total of 311 children with suspected appendicitis were included, with 193 (62%) diagnosed with appendicitis. Among these, 80 (41%) had complicated appendicitis. There was no difference in appendicitis rate between children with positive and normal urine dipstick results. Among children with appendicitis, 119 (62%) had positive urine dipstick results: 49% ketones, 29% erythrocytes, 23% protein, 19% leukocytes, and 2% nitrite. Multivariable analysis revealed that female sex (adjusted odds ratio: 2.41 [95% confidence interval, CI: 1.21-4.80], p = 0.013), retrocecal appendicitis (aOR: 2.39 [95% CI: 1.18-4.84], p = 0.015), and complicated appendicitis (aOR: 2.27 [1.01-5.13], p = 0.015) were significantly associated with abnormal urine dipstick results. Sensitivity and specificity of positive urine dipstick for complicated appendicitis was 56% (95% CI: 45-67%) and 64% (95% CI: 54-73%), respectively, with an area under the curve of 0.62 (95% CI: 0.54-0.70). Limitations in this study include potential unmeasured confounders such as hydration status and urinary tract infections.
Conclusion: Abnormal urine dipstick results are common in children with appendicitis. Urine dipstick might help identify cases of complicated and retrocecal appendicitis.
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