– When doing blood tests for drugs why does the blood have to be taken from a vain or artery?


I was watching a Police show and they couldnt prosecute a drug driver because they couldnt get a blood sample from him because of his drug use. Why (and this sounds really sadistic) can’t they take blood extracted another way?

In: Biology

The veins and arteries are where all the blood is. You can get a few drops in other places but if you want to take a significant amount, you should really find a blood vessel which carries a significant amount of blood.

It takes an amount of blood that would be painful/difficult/slow to extract some other way. Using a needle is the only practical way that doesn’t produce more concerns than it addresses.

You can get blood from anywhere but the veins carry enough volume to actually get a needle into. For infants they put the needle into veins in the scalp. The crime show wanted drama because if they wanted to prosecute they would. For a druggy that is so bad that they dont have veins left to pull from is likely not new to the system and would only need a little evidence to put away.

This makes me have another question since yours was answered. Could period blood from a menstrual cup be used for blood testing?