The Case:
A 56-year-old male with no significant past medical history presents to the emergency department with worsening swelling, pain, and erythema of the right elbow. The patient had been seen two days earlier at an outside hospital, where he received an aspiration of his right elbow out of concern for septic arthritis, though the aspirated fluid demonstrated no organisms. He was thereafter discharged home with oral antibiotics. However, he continued to have worsening range of motion of the right elbow due to pain and swelling, though he is still able to pronate and supinate his arm. He also states that the erythema of his right elbow has increased in size and tracked proximally since being seen at the outside hospital two days prior.
Patient Course:
In the emergency department, the patient received lab work that was remarkable for WBC 11.8, CRP 16.6, and ESR 26. An x-ray of the right elbow demonstrated a mild effusion with no bony abnormalities. A point-of-care ultrasound was performed, which identified thickening of the skin overlying the elbow with a cobblestone appearance, and an underlying fluid collection consistent with an olecranon bursitis. Given the worsening of symptoms over the previous two days despite antibiotic therapy, this presentation is concerning for septic bursitis. The bursa was aspirated at bedside, the patient was admitted for IV antibiotics, and he received a surgical washout of the bursa in the OR with the Orthopedic Surgery service.
Why It Matters:
Septic bursitis can be a difficult diagnosis to identify in the emergency department, and it can be challenging to distinguish from other competing diagnoses, such as cellulitis or septic arthritis. Additionally, while classically found in pressure-point areas, such as the elbow or knee, traditional imaging modalities – including x-ray, CT, and MRI – are relatively insensitive at identifying septic bursitis. Ultrasound is often a more useful imaging modality and is readily available at the bedside. Findings suggestive of septic bursitis include complex fluid in the bursa with septations (as seen in this case), as well as hyperemia on color flow doppler or gas. Bursal aspiration with fluid culture remains the gold standard for diagnosis. Empiric antibiotic coverage should be started after bursal aspiration whenever possible and directed to cover Staph aureus and Strep species, as these organisms encompass more than 90% of septic bursitis cases.
Authored by Michael Dorritie, DO
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