Final answer:
When drawing blood from the back of the hand, the tourniquet should be placed 3 to 4 inches above the puncture site, which is around the lower arm, above the wrist and below the elbow.
Step-by-step explanation:
When collecting blood from a vein in the back of the hand, it is important to properly place the tourniquet to ensure that the vein becomes more prominent and easier to puncture. The tourniquet should be positioned approximately 3 to 4 inches above the intended puncture site. In this case, that means the tourniquet would be wrapped around the lower arm, above the wrist, but below the elbow.
The tourniquet should be snug but not too tight as to cause excessive discomfort or obstruct arterial blood flow. It's essential to follow proper procedure for venipuncture to prevent complications and to collect an adequate sample for testing.