RD7.4 | Imaging in Appendicitis — Summary & Reflection

KEY TAKEAWAYS

Imaging in Appendicitis — Key Points

• Appendicitis is largely a CLINICAL diagnosis (migratory pain, anorexia, fever, RIF tenderness; Alvarado score). Imaging is for equivocal/atypical cases, specific populations and suspected complications — not every patient.
• Match the modality to the patient: Ultrasound first-line in children, young/thin adults and pregnancy (no radiation, ALARA); CT most sensitive/specific in adults, the obese and equivocal cases; MRI in pregnancy when ultrasound is inconclusive (no radiation).
• Cornerstone imaging sign: a non-compressible, blind-ending appendix >6 mm in outer diameter.
• Ultrasound signs: target/bull's-eye sign, appendicolith, peri-appendiceal fluid, increased Doppler wall flow, focal tenderness.
• CT signs: dilated (>6 mm) appendix with enhancing thickened wall, peri-appendiceal fat stranding, appendicolith, free fluid; detects complications — abscess, phlegmon, perforation.
• A non-visualised appendix does NOT exclude appendicitis — if suspicion persists, image further or observe.
• Integrate into management: uncomplicated → appendicectomy (or antibiotic-first in selected adults); contained abscess/phlegmon → IV antibiotics ± image-guided percutaneous drainage, interval appendicectomy; free perforation/peritonitis → urgent surgery; normal appendix + alternative diagnosis → redirect, avoiding unnecessary appendicectomy.

REFLECT

On your next surgical or paediatric posting, notice the imaging choices made for right-iliac-fossa pain. When a child or pregnant woman is suspected of appendicitis, ask whether ultrasound (or MRI) was chosen over CT, and listen for the ALARA reasoning behind it. When a CT is reviewed, look beyond 'appendicitis: yes/no' to the complication question — is there a contained abscess or free perforation? — because that is what changes the operation. And remember that a normal appendix on a good scan in a young woman can spare her an unnecessary operation. Linking the patient, the modality, the findings and the surgical decision into one chain of reasoning is precisely what RD7.4 is asking you to master.