How does a vacutainer (used for drawing blood) work?

Question

So... there's the needle in the arm, the tubing, and then the vacutainer that you put tubes on, but how does the vacutainer work? Is it just like a valve?

Answer 1

Vacutainer® Needle
The Vacutainer needle has a sharp point at both ends, and usually is covered by a rubber sheath, with one end being shorter than the other. The long end of the needle is used for penetrating the vein, the shorter end is used to pierce the rubber stopper of the vacuum tube. The sheath makes it possible to draw several tubes of blood by preventing leakage of blood as tubes are changed, this is called a multi-draw. If the short end is not covered with a rubber sheath, it is a single sample needle and only one tube of blood can be collected.

Answer 2

Vacutainer Blood Draw

Answer 3

When they are being produced at the factory they put a small amount of nutrient agar in the tube and autoclave the tube. The agar also contains an anticoagulant.
Once the rubber stopper is sealed while the tube is still hot, as it cools down it forms a natural vacuum.
When the stopper is pierced with the needle it draws the blood up into the tube because of the vacuum formed when it cooled.

Answer 4

AS the name implies, there is a vacuum in the collection tube. When the sheathed proximal needle pierces the color-coded rubber stopper, blood is sucked into the tube. That assumes that the distal end of the needle has successfully pierced the vein.

These tubes are relatively expensive these days, so I can't suggest you waste one, but if you pierced the stopper with a needle you would hear a swoosh.