Does abdominal pain duration affect the accuracy of first-line MRI for pediatric appendicitis?

Purpose: To compare the accuracy of first-line MRI for pediatric appendicitis between children with different durations of abdominal pain.

Materials And Methods: Between November 2012 and September 2013, 364 pediatric patients underwent MRI for clinically suspected appendicitis. Patients were stratified into one group with pain lasting less than or equal to 1 day and pain longer than 1 day.

Results: In patients with early abdominal pain, appendicitis occurred in 83 of 208 patients (39.9%) vs. 49 of 156 patients with pain longer than 1 day (31.4%, p = 0.09). Sensitivity and specificity of MRI in patients with early abdominal pain were 97.6% (95% CI [91.6%-99.3%]) and 94.4% (95% CI [88.9%-97.3%]), respectively, vs. 93.9% (95% CI [83.5%-97.9%]) and 97.2% (95% CI [92.1%-99.4%]), respectively, in patients with pain longer than 1 day in duration (p = 0.36 and p = 0.35 for sensitivity and specificity, respectively).

Conclusions: First-line MRI is accurate for acute appendicitis in children presenting with early abdominal pain, and may be appropriate as the initial examination in children. Further prospective studies are needed to compare MRI vs. ultrasound as the initial examination in children with early abdominal pain to help further delineate a diagnostic imaging algorithm.