Case 57

12 yo M no pmh presents to the ED for abdominal pain. Pt has had pain for the past 12 hours, started in the periumbilical region and has since localized to the RLQ. Associated with nausea and no vomiting. No diarrhea or constipation. No fever or chills. Normal appetite.

PE: Well appearing, non toxic. ABD: soft tender over Mcburney's point, no rebound or guarding.

 IMAGE 1

IMAGE 1

 IMAGE 2

IMAGE 2

 IMAGE 3

IMAGE 3

 

QUESTIONS:

  1. What do you see in these images?
  2. What scanning technique to you use?
  3. What probe do you use?
  4. What are the signs on US for the most likely diagnosis?

ANSWERS:

  1. Appendicitis.  Images 1-3 show a blind ended tubular structure with a diameter greater than 1cm.  In the sagittal view (image 3), you can see a fecolith with shadowing.
  2. The best scanning technique for finding appendicitis is to have the patient point to the area with the most pain and start scanning in a organized fashion in both transverse and sagittal views. A additional approach is to identify the iliac vessels and the psoas muscle in the RLQ and scan both superior and medial to those landmarks.  
  3. The linear probe should be used because the appendix is usually a very superficial structure.  In adults with more abdominal soft tissue, the curvilinear probe may be attempted, but success in identifying the appendix may be limited. 
  4. The signs of appendicitis on ultrasound include:
    1) blind ended tubular structure in sagittal
    2) target sign in transverse
    3) diameter greater than 6mm
    4) lack of peristalsis
    5) non-compressible
    6) a fecolith or peri-appendiceal fluid may be seen, but neither are necessary for the diagnosis