Why would you do an arthrocentesis for the following case?
A 46 year old male presents with an isolated swollen knee joint.¬† He has increased pain with both passive and active range of motion of the joint.
A. Absolute cell count can be used to rule out a septic etiology B. Arthrocentesis is contraindicated if infection of any kind covers the joint C. If you obtain a very small amount of synovial fluid, the most important test to be run is cell count and differential D. The most concerning complication of arthrocentesis is a ‚Äúdry tap‚ÄĚ E. Most of the white blood cells in septic arthritis are PMNs, while in inflammatory arthritis, eosinophils predominate.
Arthrocentesis is contraindicated if infection of any kind covers the joint-one of the emergency indications for arthrocentesis is obtaining joint fluid for analysis. arthrocentesis is contraindicated if infection of any kind covers the area to be punctured. the synovial fluid should be sent for cell count, differential, grams stain, crystal analysis, and culture. a positive grams stain is diagnostic, but a negative result does not rule out septic arthritis, therefore cultures should always be obtained. the likelihood ratio for septic arthritis increases as the joint wbc rises, however low wbc counts do occur early in infectious arthritis and partially treated arthritis. most of the cells in both septic and severe inflammatory arthritis are pmns. cell counts should not be used to absolutely rule out a septic etiology; bacterial cultures should be obtained. the most serious complication of arthrocentesis is introducing infection into the joint space. other complications include bleeding, allergic reaction to anesthetic agents, dry taps. (chapter 114)