A blood test was any test performed on a sample of blood.
Christine Chapel claimed to have run a number of blood tests on Spock because it was not true Vulcan blood either, and it had Human blood elements in it. (TOS: "Journey to Babel")
Following the discovery of the Founders in the Alpha Quadrant, blood screening was a popular, but ineffective type of blood test administered to individuals, and for a time was increasingly done so on Earth in 2372. (DS9: "Homefront", "Paradise Lost")