Tips on Appendix Ultrasound

Appendix Ultrasound:  Tips to improve your chances of sonographic success. 

Normal appearances of the appendix on ultrasound in a sagittal plane.

Normal appearances of the appendix on ultrasound in a transverse plane.


Appendicitis, and particularly a normal appendix, can be particularly difficult to see on ultrasound. Those who perform it regularly can be extremely adept at finding both a normal and inflamed appendix. So, we put together some helpful tips and advice to help those who are looking to improve their skills. Firstly, wherever possible try to work alongside someone who performs the scan regularly until you feel confident as even those more experienced find it difficult sometimes. They will be able to offer invaluable skills and experience that will help, whether that’s common places to find it (yes, its position can be quite variable) or how to improve your scan settings, scanning the appendix can be very tricky so it’s best to try and have the best chance of success.

If you can’t get detailed, hands-on training alongside an expert then these hints and tips will help you on your way.

  • Use a linear probe in the region of 5-7MHz. Larger patients may require the use of a lower frequency curvilinear probe.  
  • As we alluded to earlier, the appendix can move about and can sometimes be seen as high as the RUQ. 
  • A good starting point is to image the Morrison’s Pouch and look for free fluid. 
  • Move down the abdomen and ask the patient which area is most tender, but beware in acute appendicitis there can be severe rebound tenderness (it’s worth warning the patient in advance about this). 
  • Image in sagittal with and without Power Doppler, measure whole thickness and wall thickness (if I can) and try to visualize the blind end to ensure you are not seeing a different area of bowel.
  • Image in a transverse place with and without Doppler with and without compression with measurements for both.
  • Fat stranding can sometimes alert you to an area of interest –  i.e. increased echogenicity of the pericaecal and periappendiceal fat
  • Graded compression (gradual increase in pressure in order to displace overlying bowel gas) should hopefully identify a blind-ended sausage-shaped structure with LITTLE OR NO peristalsis in the region of maximum discomfort.
  • Bull’s eye/target appearance in cross section.
  • Power Doppler should show increased vascularity.
  • The normal appendix has a diameter of less than 6mm. But beware that is a slim patient with a well visualized, superficial appendix, it can look big! So be sure to always measures thickness. 
  • Look for a periappendiceal collection
  •  In female patients it’s also worth imaging the right ovary to rule out ovarian cysts/pathology as the cause of pain.

Lastly, we’ve chosen a few of the best videos from the web which we think you’ll love. So enjoy!

A great appendix Ultrasound by Practical Sonography. To see more of their ultrasound videos follow their channel here.

Appendix Ultrasound by Radiology Nation. To follow their channel click here.

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