Abstract: An integral catheter and blood tester includes a needle unit which is receivable within a conventional catheter intravenous tube and housing. The catheter supports a piercing needle and interior chamber. A transparent tester housing is coupled to the needle unit and supports a test strip and test patch which extends into the flash chamber of the catheter needle. A constricting valve surrounds the test strip to maintain closure of the flash chamber. Once the catheter and needle have been inserted into the desired blood vessel, a quantity of blood is introduced into the flash chamber so as to wet the test patch. The test patch may, for example, include conventional litmus material used to test the pH of the test sample. Once the flash process is complete, the needle and tester housing are withdrawn from the catheter to permit conventional intravenous coupling to the catheter. Thereafter, the tester housing is separable from the needle unit to permit discarding of the needle unit.