Ultrasound of the Week #008

Thanks to Dr Serena Rovida, Emergency Medicine SpR for this great case and images.


A male in his early twenties presented with severe abdominal pain, nausea and vomiting present for 2 days.

A bedside ultrasound of his lower abdomen was performed showing the following images:

Question 1: What does it show?
[expand title=”Answer 1: ” tag=”h3″] This shows a dilated, non-compressible appendix >6mm (diagnostic for appendicitis). [/expand]

Question 2: What are the structures A, B and C?
[expand title=”Answer 2: ” tag=”h3″] A: Iliac artery (non-compressible) B: Iliac vein (compressible) C: Appendix.
This patient was rapidly referred to surgeons and admitted for appendicectomy. [/expand]<br>

[expand title=”Point-of-Care-Ultrasound for Appendicitis:” tag=”h2″ trigclass=”noarrow”]

POCUS can be used to identify acute appendicitis in patients with moderate to high pre-test probability.[1]  A high specificity yet lower sensitivity make it a rule-in but not a rule-out test (not to be used as a screening tool).  As the appendix can vary significantly in position, it is not uncommon to be difficult or impossible to locate.


-Graded compression to mobilise the overlying gas

-The classic approach is sweeping the entire RLQ with a ‘lawnmower’ technique [2]

Summary of Findings:

Acute appendicitis:

  • Much easier seen when abnormal: blind-ended tubular structure, overlying psoas muscle and iliac vessels, with thickened walls, >7mm( outer diameter) considered abnormal (6mm cut-off may lead to high sensitivity and lower specificity[3]).
  • Surrounded by inflamed mesenteric fat: bright echogenic area +/- few lymph nodes
  • Thickened wall with well demarcated mucosal layers due to oedema 
  • False negatives: missing tip appendicitis
  • False positives: inflammation secondary to other intra-abdominal processes (Crohn’s, PID, etc.)

Secondary signs:

  • Sonographic McBurney’s: selective compression over suspected structure causing pain
  • Appendicolith: highly suggestive, echogenic structure with post-acoustic shadow
  • Wall hyperaemia with loss of definition at later stages
  • Thickened bright echogenic mesenteric fat
  • Mesenteric lymph nodes
  • Free fluid wedges or larger focal fluid in the RLQ or diffuse in case of perforation
  • Ileus
  • Collection


  • Terminal ileum/small bowel (normal)
  • Terminal ileitis
  • Mesenteric adenitis: 3-5 lymph nodes >5mm in diameter but no other secondary signs
  • Ovarian pathology
  • Meckel’s diverticulum: cystic structure (rare)



  1. Fields MJ, Davis J, Alsup C, et al. Accuracy of point-of-care ultrasonography for diagnosing acute appendicitis: a systematic review and meta-analysis.Acad Emerg Med. 2017;24(9):1124-36.
  2. Sivitz AB, Cohen SG, Tejani C.  Evaluation ofacute appendicitis by pediatric emergency physician sonography.Ann Emerg Med 2014; 64(358–64): e4.
  3. H P Chicaiza, L Malia, C H Mulvey, S R Smith​.Revisiting the Appendiceal Diameter via Ultrasound for the Diagnosis of Acute Appendicitis, Pediatr Emerg Care. 2018 Nov;34(11):757-760
  4. Benabbas R, Hanna M, Shah J, et al. Diagnostic accuracy of history, physical exam, laboratory tests and point-of-care-ultrasound for pediatric acute appendicitis in the emergency department: a systematic review and meta-analysis.Acad Emerg Med. 2017;24(5):523-51.

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