Workup -Approach Considerations 少 Arthrocentesis关节穿刺术 of the affected joint is mandatory for all pati ents with new onset of acute monoarthritis. Tophi also may be aspi rated for crystal analysis under polarizing microscopy Septic arthritis must be diagnosed and treated promptly, because ir reversible damage can occur wIthin and the joint can be completely destroyed within 24-48 hours Send joint fluid for fluid analysis, including cell count and differentia I, Gram stain, culture and sensitivity, and microscopic analysis for c rystals In gout, crystals of monosodium urate (MSU) appear as ped intracellular and extracellular crystals. pseudogout shows cal cium pyrophosphate,焦磷酸盐(CPP) crystals, which appear shorter th an MSU crystals and are often 长斜方形的 浙医二院11 浙医二院 Workup –Approach Considerations Arthrocentesis关节穿刺术 of the affected joint is mandatory for all pati ents with new onset of acute monoarthritis . Tophi also may be aspi rated for crystal analysis under polarizing microscopy Septic arthritis must be diagnosed and treated promptly, because ir reversible damage can occur within 4-6 hours, and the joint can be completely destroyed within 24-48 hours. Send joint fluid for fluid analysis, including cell count and differentia l, Gram stain, culture and sensitivity, and microscopic analysis for c rystals. In gout, crystals of monosodium urate (MSU) appear as needle-sha ped intracellular and extracellular crystals. ..pseudogout shows cal cium pyrophosphate焦磷酸盐 (CPP) crystals, which appear shorter th an MSU crystals and are often rhomboidal.长斜方形的