A 27 year old man presents with pain localised to the RIF. Clinically there is mild psoas irritation and tenderness to deep palpation without frank peritonism. He is relatively well and has previously had renal colic.
The surgeons wonder about renal colic and request an ultrasound.
View 2: Appendix in transverse section from tip to base.
Describe and interpret these scans
Image 1: Transverse view of the RIF – showing the appendix in longitudinal section.
A blind ending tubular structure with bowel wall signature arises from the caecum laterally and passes medially lying on psoas, ending just above the iliac vessels. It measures up to 10mm across toward the tip, is non-compressible and there is no peristalsis. Probe pressure over the appendix reproduces his pain. This is typical for uncomplicated appendicitis.
Image 2: Following the appendix in transverse section from tip to base.
Image 4 Variable position and shape of the appendix.
Image 5 Some variations in appearance of appendiceal pathology.
It is unusual to get an appendix as photogenic as this.
The appendix varies in position, size and shape, and the sonographic appearance of appendicitis is very varied.
The lumen may be distended by anechoic fluid or filled with more echogenic debris, and may contain a calcified appendicolith. Alternatively the lumen may not be particularly distended.
The wall may demonstrate the 5 layers beautifully, or may be more poorly defined, particularly when there is more marked inflammatory change or necrosis or even rupture.
Para-appendiceal changes may include echogenic inflamed fat, anechoic free fluid, or more echogenic debris filled fluid where there is an abscess. Mesenteric lymphadenopathy is also not infrequent.
In this case the compliant but inflamed appendix was straight, of average length, and able to be shown on a single still image. It was mildly dilated but this appendicitis was not complicated by necrosis nor perforation nor abscess formation.
Take home messages:
- Appendicitis is a challenging scan and the highly varied appearances make error common. My advice is to leave it to the experts – or put in the effort and become one!
- Clips are particularly useful in demonstrating the entire appendix from blind ending tip to origin at the caecum – and can convince understandably skeptical surgical colleagues that what you are seeing is actually the appendix.