Ultrasound is a powerful tool for helping radiologists diagnose pediatric appendicitis, and it doesn’t much matter whether the interpreters are trainees working the night shift or daytime attendings. However, the residents and fellows in the study behind the result didn’t do as well at ruling out the condition when it wasn’t present, prompting the study authors to recommend more intensive training to avoid false positives.

Kate Louise Mangona, MD, of Texas Children’s Hospital and colleagues published their work online Aug. 18 in Academic Radiology.

The researchers correlated pediatric appendicitis scores from 2,935 ultrasound interpretations with subsequent intraoperative diagnoses and clinical follow-up.

They analyzed the diagnostic performance of the trainees and measured interobserver agreement with the findings of the attending radiologists.

The team found the attendings had sensitivity, specificity, accuracy, negative predictive value and positive predictive value of, in that order, 94.0 percent, 93.7 percent, 93.8 percent, 97.9 percent and 83.4 percent.

For the trainees, the corresponding results were 92.0 percent, 91.2 percent, 91.3 percent, 97.5 percent and 75.2 percent.

Trainee and attending agreement was high (k = 0.995), the authors report, but there were notably more false positives at night (7 percent) than during the day (4.7 percent).

The appendicitis scores that were most frequently discordant between the two groups were those indicating a completely visualized normal appendix, a nonperforated appendicitis and an equivocal interpretation.

In their discussion, Mangona et al. comment on the tendency the trainees evidenced to overcall (false positives) rather than undercall (false negatives).

This tendency “could be explained by a fear of missing the diagnosis or simple inexperience and lack of understanding of the most current diagnostic criteria for appendicitis on ultrasound,” they write. “Radiology trainees rarely perform or interpret appendicitis ultrasound examinations at adult hospitals, and their first exposure to appendiceal ultrasound may be during their initial pediatric radiology rotation.”

Ultrasound “shows high diagnostic performance and very high interobserver agreement for pediatric appendicitis when interpreted initially either by on-call radiology trainees during night shifts or by faculty radiologists during day shifts,” the authors conclude. “However, the lower specificity and positive predictive value of ultrasound when interpreted at night by trainees without concurrent faculty oversight warrants educational efforts focused on the most contemporary diagnostic criteria for appendicitis and avoidance of false-positive examinations by trainees.”