Revised ultrasound criteria for appendicitis in children improve diagnostic accuracy

Use of CT in the evaluation of suspected appendicitis in children is common. Expanding the use of US would eliminate the radiation exposure associated with CT.

We describe new criteria that improve US's diagnostic accuracy for appendicitis, making it more comparable to CT in terms of sensitivity and specificity.

We conducted a retrospective review of 304 consecutive patients undergoing US for the diagnosis of appendicitis in our institution during 2006. The sensitivity, specificity and accuracy of the maximal outer diameter (MOD) at various measurements was calculated and compared to pathology results. Additional variables (appendiceal wall thickness, fecalith, hyperemia, fat stranding, free fluid, age and weight) were also evaluated.

The highest sensitivity (98.7%) and specificity (95.4%) were identified when MOD was ≥7 mm or wall thickness was >1.7 mm. These values resulted in correctly classifying 96.6% of cases, with 1 (0.5%) false-negative and 6 (2.9%) false-positive studies. Incorporating secondary signs of appendicitis, age or weight did not alter accuracy.

These findings identify new US criteria that compare favorably to CT. In children with suspected appendicitis, using US as the initial imaging study will ultimately lead to improved accuracy, lower cost and the elimination of ionizing radiation exposure.