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Dx: Joint Effusion Detected on Bedside Ultrasound
Figure 1 (previous page) demonstrates a moderate sized joint effusion around the distal ulna. The fluid is black and anechoic surrounding the hyperechoic, bright white bony cortex. Note the acoustic shadow farfield to the hyperchoic bone (Figures 3 and 4). Once you see that there is ample fluid to tap, you decide to proceed with the arthrocentesis. You take a few moments to review how to perform the procedure in your favorite pocket ED reference guide, and you scout out an area on his skin that appears clear of any overlying redness or signs of cellulitis. Using ultrasound guidance, you measure how deep the fluid pocket lies, and scan around the area until you find an unobstructed path towards the largest collection of fluid.
Your successful tap reveals positively birefringent crystals, no bacteria, but 74,000 WBC’s per high-powered field. You decide to start treatment for gout. Given his age and risk for co-infection, you and the medicine team decide to admit him for IV antibiotics until his fluid cultures are finalized. Fortunately, his cultures come back negative and the patient is eventually discharged home on hospital day 2 with naproxen and close follow-up.
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