Labs: CBC, ESR/CRP, pre-op labs (T+S, coags, Chem-10)
X-Ray
Usually normal but helpful to rule out bony involvement, FB
Blood culture (if possible, obtain from synovial fluid)
Usually normal but helpful to rule out bony involvement, FB
Infectious tenosynovitis
Calcaneal bursitis
Calcific tendinitis
Septic bursitis
Olecranon bursitis 
Flexor tenosynovitis
Prepatellar bursitis 
Pes anserine bursitis