Biomarkers to distinguish surgical etiologies in females with lower quadrant abdominal pain.

OBJECTIVES: Lower abdominal pain is a common complaint in girls and young women presenting to a pediatric emergency department (PED). An extensive evaluation may be required to exclude surgical emergencies such as appendicitis and ovarian torsion. However, clinicians and families prefer to limit invasive procedures and radiation exposure. The literature suggests that serum biomarkers such as the cytokine interleukin-6 (IL-6) can predict ovarian torsion in adults, while the membrane glycoprotein cluster of differentiation-64 (CD64) has been linked with bacterial infections and sepsis. Therefore, the study objective was to assess whether plasma IL-6 or neutrophil CD64 surface levels would assist clinicians in distinguishing surgical diagnoses (ovarian torsion and appendicitis) from nonsurgical diagnoses in young females with lower abdominal pain.

METHODS: This study was a prospective, cross-sectional, pilot study of young females presenting with lower abdominal pain. Demographics, clinical and laboratory data, and final diagnoses were recorded. Plasma IL-6 and neutrophil CD64 were quantified. Nonparametric Kruskal-Wallis test was used to detect significant differences in IL-6 and CD64 values between surgical and nonsurgical patients. Further analysis was done to detect differences among the surgical patients (appendicitis vs. ovarian torsion). A bivariate analysis using the Wilcoxon rank sum was used to test for significant differences in IL-6 and CD64 by selected clinical factors.

RESULTS: There were 112 female subjects ages 6 to 21 years enrolled. Final diagnoses were grouped as appendicitis (n = 38, 34%), ovarian torsion (n = 15, 13%), and nonsurgical (n = 59, 53%). Surgical cases had significantly higher levels of IL-6 compared to nonsurgical cases (p < 0.0001), and appendicitis patients had significantly higher CD64 indexes compared to ovarian torsion patients (p = 0.007). The clinical characteristics of fever of ≥38°C (p = 0.0002) and constant pain (p = 0.02) were significantly associated with elevated IL-6. Fever of ≥38°C (p = 0.02) was significantly associated with a higher CD64 index.

CONCLUSIONS: Interleukin-6 was significantly elevated in surgical patients compared to nonsurgical patients in this sample of young females, and CD64 was significantly elevated in appendicitis patients compared to ovarian torsion patients. These data suggest that with larger sample sizes and future confirmatory studies, these biomarkers may be useful in the evaluation of young women with lower quadrant abdominal pain.