Ultrasound First for Appendicitis in Adults?

January 25, 2023

Written by Gabby Leonard

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When performed by an experienced EM physician or radiologist, a conclusive appendix ultrasound is both sensitive and specific when evaluating for acute appendicitis and can be used in place of CT.

Why does this matter?
Abdominal pain is the most common complaint in emergency department presentations. CT scan is the gold standard for diagnosing acute appendicitis (AA); however, it may be costly, time-intensive, and could expose patients to unnecessary radiation if negative.

Did you say Sound Waves??
This retrospective analysis looked at 508 adult patients with suspected AA who received an ultrasound as their first imaging study by either an EM physician or radiologist to determine if this testing modality is adequate for appropriate diagnosis. EM physicians were considered experienced if they were credentialed in abdominal ultrasound by having performed >200 scans and had completed a three-day course.

Of patients who had a “conclusive” ultrasound, sensitivity for AA was 89.6% (95%CI 82.1-94.3%) and specificity was 93.8% (89.1-96.6%). Ultrasound diagnosis of AA involved appendix diameter >6mm, pain with compression, non-compressible, peri-appendiceal fluid, and echogenicity.

If the appendix was not visualized, it was considered “inconclusive.” 29% of patients with inconclusive ultrasounds ended up having AA; thus, these patients warranted close follow-up or further imaging with CT. Even with a negative ultrasound, patients should have close follow-up due to potential for missed diagnoses.

Source
Diagnostic accuracy of a pragmatic, ultrasound-based approach to adult patients with suspected acute appendicitis in the ED. Emerg Med J. 2022 Dec;39(12):931-936. doi: 10.1136/emermed-2019-208643. Epub 2022 Mar 17.