Ultrasound Case: Acute Appendicitis

A 12-year-old male with right lower quadrant pain and fever - Radiology case study

Case Presentation

History

• Chief Complaint: Right lower quadrant pain and fever
• History of Present Illness:
  • Periumbilical pain migrating to RLQ over 24 hours
  • Pain worsens with movement and coughing
  • Low-grade fever (38.1°C)
  • Anorexia for past 12 hours
  • No diarrhea or urinary symptoms
• Past Medical History:
  • No previous abdominal surgeries
  • No similar episodes in the past
• Initial Labs: WBC 14.5 × 10³/µL (neutrophil predominance), CRP 32 mg/L

Ultrasound Findings of Appendicitis

• Non-compressible Appendix: Diameter >6mm with lack of compressibility
• Wall Thickening: Hyperechoic wall with target sign appearance
• Periappendiceal Fat: Hyperechoic mesenteric fat surrounding the appendix
• Free Fluid: Small amount of complex fluid adjacent to the appendix

1. Non-compressible appendix

• Dilated appendix (8.7mm) that fails to compress with transducer pressure
• Loss of normal wall layers

2. Target sign appearance

• Concentric rings of alternating hyper- and hypoechogenicity
• Indicates wall edema and inflammation

3. Inflamed periappendiceal fat

• Hyperechoic fat surrounding the appendix (asterisk)
• Small amount of adjacent free fluid

Differential Diagnosis for Right Lower Quadrant Pain

• Mesenteric Adenitis: Enlarged mesenteric lymph nodes without appendix changes.
• Omental Infarction: Hyperechoic omental mass with no connection to appendix.
• Right Ovarian Pathology (in females): Ovarian cyst or torsion with normal appendix.
• Diverticulitis (in adults): Thickened colon wall with diverticula, normal appendix.
• Gastroenteritis: Normal appendix, diffuse bowel wall thickening, often with diarrhea.

Reference articles

Ultrasound of Acute and Chronic Appendicitis

Appendicitis: Imaging Diagnosis (Ultrasound and CT)

Ultrasound of the appendix (Normal and pathological findings)