Urinary cytology, the examination of cells and other materials in urine, was used by George N. Papinicolaou and Victor F. Marshall to diagnose cancer of the bladder. 1
1. Papinicolaou, G.N., and Marshall, V.F. "Urine Sediment Smears as a Diagnostic Procedure in Cancers of the Urinary Tract." Science. 101 (1945): 519-520. [PUBMED]