This invention is a device which can be used to obtain a sample of blood from a person or animal. It incorporates parts of two existing devices (syringes and Vacutainers) into one device in a new configuration, and it reduces or eliminates some of the disadvantages of each of these two existing devices. Unlike the typical use of a syringe, a sample of blood is transferred directly from the blood vessel of a person or animal to the test tube or similar container that is sent to a laboratory for testing. Unlike a Vacutainer, the differential pressure between the two ends of a hypodermic needle can be controlled while the device is being used.
