Psoas abscess

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Background

Psoas major and nearby muscles.
Horizontal disposition of the peritoneum in the lower part of the abdomen, showing psoas major.
  • Primary infection
    • Psoas muscle is susceptible to infection from distant sites due to rich blood supply, proximity to overlying retroperitoneal lymphatic channels
  • Secondary infection
    • Direct spread/extension via adjacent infection
    • S. aureus is most common pathogen (80%)

Clinical Features

Late finding of a large psoas abscess progressing to visible left buttock mass with erythematous skin eruption.
  • Abdominal pain radiating to hip, flank
  • Pain with thigh flexion (esp against resistance)
  • Limp
  • Fever
  • Nausea
  • Back pain[1]

Differential Diagnosis

Hip pain

Acute Trauma

Chronic/Atraumatic

RLQ Pain

LLQ Pain

Evaluation

Psoas muscle abscess on CT.
Psoas muscle abscess on CT.
(A) Abdominal computed tomography, revealing abscess formation on the left psoas muscle, which was depicted as a localized low density area. (B) Magnetic resonance imaging shows multiseptated psoas abscess and gluteal abscess.

Work Up[2]

  • Lab Studies
  1. CBC
  2. Chem-10
  3. Lactic
  4. Blood cultures
  • CT abdomen/pelvis with contrast (imaging study of choice)[3]
  • MRI has higher sensitivity (if available)[4]
  • Lower accuracy with US
  • MRI or US preferred in pregnant patients

Diagnosis

  • Typically on imaging

Management

See Also

References

  1. Dietrich A, Vaccarezza H, and Vaccaro CA. “Iliopsoas abscess: presentation, management, and outcomes,” Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, vol. 23, no. 1, pp. 45–48, 2013.
  2. Shields D, Robinson P, Crowley TP. “Iliopsoas abscess—a review and update on the literature,” International Journal of Surgery. 2012; 10(9): 466–469.
  3. Hosn S. Psoas muscle abscess. Radiology Reference Article. Radiopaedia.org. Radiopaediaorg. 2015. Available at: http://radiopaedia.org/articles/psoas-muscle-abscess. Accessed May 21, 2015.
  4. Hosn S. Psoas muscle abscess. Radiology Reference Article. Radiopaedia.org. Radiopaediaorg. 2015. Available at: http://radiopaedia.org/articles/psoas-muscle-abscess. Accessed May 21, 2015.