Appendicitis is the most common surgical emergency of the abdomen. Clinical scores help estimate risk, but imaging has reduced negative appendicectomy rates considerably.
Start with a risk score
Scores such as the Alvarado score, the Appendicitis Inflammatory Response score or the Pediatric Appendicitis Score sort patients into low, intermediate and high risk, and guide who needs imaging.
Children
Ultrasound is the first-line test. A non-compressible appendix of more than 6 mm diameter with surrounding inflammation supports the diagnosis. If ultrasound is inconclusive, observation and repeat examination — or MRI where available — are preferred over CT.
Pregnancy
Ultrasound comes first. When it is non-diagnostic, MRI without gadolinium is the next step and avoids ionising radiation.
Adults
CT is the most accurate test in adults, and low-dose protocols perform well. Ultrasound is a sensible first step in young, slim patients.
Imaging at a glance:
- Children – ultrasound, then MRI or observation
- Pregnancy – ultrasound, then MRI
- Adults – CT, ideally low-dose
“Choose the test that answers the question with the least harm to the patient in front of you.”
This article is for education only and does not replace clinical judgement or local guidelines.
