Validation of the Appendicitis Inflammatory Response (AIR) score during pregnancy: A nested case-control study.

Objectives: Appendicitis poses diagnostic challenges. A correct diagnosis is important during pregnancy to avoid unnecessary surgery on the one hand and delayed surgery on the other hand, as both may negatively affect pregnancy outcomes. Clinical scores for risk-stratified management of suspected appendicitis are well established in adults but have not been validated during pregnancy. This nested case-control study evaluated the diagnostic accuracy of the Appendicitis Inflammatory Response (AIR) score and imaging during pregnancy.

Methods: By cross-linking national Swedish health registries from a defined geographical area, we identified a cohort of 154 women who underwent appendectomy for suspected appendicitis during pregnancy and a matched cohort of 232 pregnant women admitted for acute abdominal pain and suspected appendicitis but with a discharge diagnosis of nonspecific abdominal pain (NSAP). All variables were extracted from medical records. The diagnostic value of AIR score and imaging was estimated for patients with a final diagnosis of appendicitis compared with patients with negative appendectomy and NSAP patients.

Results: The final diagnoses for the operated patients were uncomplicated and complicated appendicitis in 49.4% and 26.6%, respectively, and negative appendectomy in 24.0%. Nearly half of all the patients underwent diagnostic imaging (41%), mainly by ultrasonography. The sensitivity and specificity of diagnostic imaging were 44.9% (95% CI 32.9%-57.4%) and 42.2% (95% CI 31.9%-53.1%), respectively. The area under the receiver operating characteristic curve of AIR score was 0.88 (95% CI 0.84-0.92) for all appendicitis and 0.90 (95% CI 0.84-0.95) for complicated appendicitis. The sensitivity for complicated appendicitis was 100% at a score of ≥4. The specificity for all appendicitis was 97% at a score of ≥9.

Conclusions: The results of this study suggest that the AIR score may be a suitable diagnostic tool for risk stratification of pregnant women with abdominal pain and suspected appendicitis but further validation among pregnant women is needed.