Does age affect the test performance of secondary sonographic findings for pediatric appendicitis?

Neal, Jeffrey T.; Monuteaux, Michael C.; Rangel, Shawn J.; Bachur, Richard G.; Barnewolt, Carol E.

BACKGROUND: Secondary sonographic findings of appendicitis can aid image analysis and support diagnosis with and without visualization of an appendix. OBJECTIVE: We sought to determine if age affected the test performance of secondary findings for pediatric appendicitis. MATERIALS AND METHODS: We performed a medical record review of emergency department patients younger than 19 years of age who had a sonogram for suspected appendicitis. Our primary patient outcome was appendicitis, as determined by pathology or by image-confirmed perforation/abscess. Our primary analysis was test performance of secondary sonographic findings as recorded by sonographers on the final diagnosis of appendicitis stratified by age (<6 years, 6 to <11 years, 11 to <19 years). RESULTS: A total of 1,219 patients with suspected appendicitis were evaluated by ultrasound, and 1,147 patients met the criteria for analysis. Of the 1,147 patients, 431 (37.6%) had a final diagnosis of appendicitis. Across all age groups, echogenic fat was the most accurate secondary finding (92.5% [95% confidence interval (CI): 91.0, 94.0]) and free fluid was the least accurate secondary finding (54.7% [95% CI: 51.8, 57.5]). There was no significant difference in the age-stratified test performance of secondary sonographic findings except that (1) appendicolith was a more accurate predictor in patients <6 years old than in the middle group (P<0.001) or the oldest group (P<0.001), and (2) free fluid was a more accurate predictor in the middle group than in the oldest group (P=0.02). CONCLUSION: There are no significant differences in the age-stratified test performance of secondary sonographic findings in the prediction of pediatric appendicitis except that appendicolith is more predictive in younger patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00247-021-05100-0.