serodiagnosis

noun

se·​ro·​di·​ag·​no·​sis ˈsir-ō-ˌdī-ig-ˈnō-səs 

plural serodiagnoses -ˌsēz 

: diagnosis by the use of serum (as in the Wassermann test)

serodiagnostic

-ˈnäs-tik 

adjective