Case Review: Ultrasound of Acute Appendicitis

Radiology Lectures | Radiologist Headquarters

In this radiology lecture, we review the ultrasound appearance of acute appendicitis with three unique cases!

Key teaching points include:

• Ultrasound is the first-line imaging modality in pediatric and pregnant patients due to lack of ionizing radiation: Sensitivity/specificity approximately 80%.
• Technique: Linear transducer with graded compression at site of maximal tenderness using gradual increased pressure to displace normal bowel gas.
• Inflamed appendix appears as a noncompressible, blind-ending tubular structure arising from cecum.
• Outer appendiceal diameter with compression: Less than 6 mm almost always normal, 6-8 mm borderline, greater than 8 mm highly suspicious.
• Thickened appendiceal wall (greater than 2 mm).
• Wall hyperemia: “Dot flow” normal, continuous linear/curvilinear flow highly suspicious.
• Increased echogenicity and expansion of peri-appendiceal fat due to infiltration by inflammatory cells and edema.
• Hyperechoic appendicolith with posterior acoustic shadowing supportive.
• Identify terminal ileum separate from appendix to differentiate from ileitis, Meckel’s diverticulum, or other small bowel abnormality.
• Appendix does not exhibit peristalsis.
• Right lower quadrant free fluid and lymphadenopathy supportive, but nonspecific in isolation.
• Loss of wall stratification suspicious for necrotic/gangrenous appendicitis, and color Doppler flow may be absent.
• Gas in appendix appears as dirty shadowing and ring-down artifact. Intraluminal gas sometimes helpful to exclude appendicitis, but can also be seen with gangrenous complication.
• Peri-appendiceal gas-containing collections highly suspicious for perforation. CT may be needed for clarification.

References:
1) Madhuripan N, Jawahar A, Jeffrey RB, Olcott EW. The Borderline-Size Appendix: Grayscale, Color Doppler, and Spectral Doppler Findings That Improve Specificity for the Sonographic Diagnosis of Acute Appendicitis. Ultrasound Q. 2020;36(4):314-320.
2) Fallon SC, Orth RC, Guillerman RP, et al. Development and validation of an ultrasound scoring system for children with suspected acute appendicitis. Pediatr Radiol. 2015;45(13):1945-1952.

To learn more about the Samsung RS85 Prestige ultrasound system, please visit: https://www.bostonimaging.com/rs85-prestige-ultrasound-system-4

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