Suspected Acute Appendicitis (5) - US Techniques

Ultrasound in patients with acute abdomen requires a 'graded compression' technique

Why Graded Compression Technique Required?

• To displace fat and bowel away from transducer (so there is less distance from transducer to organ of interest, i.e. appendix)
• To test reaction of that structure to compression

How to Perform Graded Compression?

• Use a linear, high-frequency transducer
• Use thin liquid ultrasound gel
  
• Slow and gentle compression (similar to palpation)
• Perform to the entire abdomen"mowing the lawn" to screen for bowel pathology "pathologic bowel usually readily stands out"
  

How Good Is It?

• To confirm appendicitis (as high as 90%) (Ref #1)
  
• To exclude appendicitis by 1) visualization of normal appendix (50%), 2) demonstration of an alternative condition (20%) (Ref #1)
  
• To alter clinical management (decision to operate change from no to yes, and vice versa) in 28%-32% (Ref #2)
  

References:
1. Puylaert J. Ultrasonography of the acute abdomen: gastrointestinal conditions. Radiol Clin N Am 2003;41:1227.
2. Gracey D, McClure M. The impact of ultrasound in suspected acute appendicitis. Clin Radiol 2007;62:573.

Related Posts:
Suspected acute appendicitis (1)
Suspected acute appendicitis (2)
Suspected acute appendicitis (3) - when and why doing imaging studies?
Suspected acute appendicitis (4) - CT techniques