When analyzing joint aspirate, what finding would indicate the diagnosis of gout?

The identification of needle-shaped, negatively birefringent crystals in the analysis of joint aspirate is indicative of gout. In this condition, the presence of monosodium urate crystals is responsible for the inflammatory response that characterizes gouty arthritis. When viewed under polarized light microscopy, these needle-shaped crystals demonstrate a specific optical property known as negative birefringence, which is a hallmark finding in gout.

Other findings in joint aspirate analysis can provide useful information but do not specifically confirm the diagnosis of gout. For instance, an elevated white blood cell count may suggest inflammation or infection but is not specific for gout. Clear synovial fluid can indicate non-inflammatory conditions or early stages of gout, but this alone does not provide a definitive diagnosis. Rhomboid shaped crystals are associated with pseudogout, which is caused by calcium pyrophosphate dihydrate crystals, a different condition than gout. Therefore, the presence of needle-shaped, negatively birefringent crystals is the key finding that confirms gout.