Health and Medicine Question #9313

Calum, a 20 year old male from Toronto asks on April 19, 2016,

I recently started donating blood and noticed after each donation, within hours, the vein that was used had moved completely out of the way of the scab from the needle. Does the body have a way of shifting major veins away of wounds or affected areas, or am I imagining things?

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The answer

Cardiac nurse from Vancouver General Hospital answered on April 21, 2016

If you notice your own veins in your hands, wrists, etc, and play with them a bit, you will see that they roll this way and that, depending on which way you shove your skin. So they are actually quite mobile under your skin. Veins are also very stretchy, almost like elastics, and can expand and contract to accommodate various amounts of blood volume, depending on how hydrated you are. That's why they are more noticeable at times than others.

When a phlebotomist is poking a vein in the bend of the elbow (the antecubital fossa) they have to make sure that the skin is really really taut, by making the surface of the arm as flat as possible, so they will pull the skin quite firmly towards the hand. By doing so, the vein underneath, which is usually so mobile, won't move away once the skin is pierced by the needle en route to accessing the vein. It needs to be a direct route through the skin and into the vein, or they will "miss" the vein.

Once you've given your blood, and the needle has been removed, your skin and your vein go back to their normal resting positions. Later you can see from your scab that where the skin got poked is actually in a different place from where the vein got poked. This is because of all the maneuvering that was done during the procedure.

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