Hip Ultrasound and Arthrocentesis

General Info/Intro

Bedside ultrasound can be used to evaluate and diagnose hip effusions when concerned for septic joint. It is both effective in visualizing an effusion and assisting in arthrocentesis.1 Emergency physicians with ultrasound training have been shown to be capable of visualizing effusions of the hip with a sensitivity between 80-85% and specificity between 98-100%.2


  • Orient curvilinear probe with the indicator toward the patient’s umbilicus (approximately 30 degrees off axis of the femoral shaft)
  • Locate femoral head and neck and measure the largest fluid collection
  • >5mm effusion or >2mm effusion compared to healthy side = positive finding


  • Use sterile probe cover and sterile technique
  • Orient needle in long axis (parallel to the probe) to visualize the entire shaft during aspiration
  • Common labs include cell count with diff, gram stain, and culture (most important)


  • Orient probe marker to umbilicus
  • Effusion >5 mm or a difference >2 mm from asymptomatic contralateral side = positive finding

Bottom Line/Pearls & Pitfalls

  • No fluid does not necessarily mean a negative septic joint


Normal sonographic hip
Normal sonographic hip
Positive joint effusion
Positive joint effusion

Further Reading / References

  1. Marx, J., Hockberger, R., Walls, R. (2013). Rosen’s Emergency Medicine- Concepts and Clinical Practice (8th ed., pp. 1845). Philadelphia, PA: Elsevier.
  2. Vieira R, Levy, J. Bedside Ultrasonography to Identify Hip Effusions in Pediatric Patients. Ann Emerg Med. 2010; 55:284-289.
  3. Reynolds, J., Euerle, B. Images in Emergency Medicine. Ann Emerg Med. 2011; 57: e18-e19.
  4. http://www.ncbi.nlm.nih.gov/pubmed/23960065
  5. http://www.ncbi.nlm.nih.gov/pubmed/22942931
  6. http://www.ncbi.nlm.nih.gov/pubmed/22284975
  7. http://www.ncbi.nlm.nih.gov/pubmed/18403170
  8. http://www.ncbi.nlm.nih.gov/pubmed/17157689
Edited by Alex Koyfman

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