It is apparently a means to double check and make sure you are injecting into a muscle and not into a blood vessel by seeing if you can draw blood at that site

It is apparently a means to double check and make sure you are injecting into a muscle and not into a blood vessel by seeing if you can draw blood at that site before you actually inject anything. https://askinglot.com/what-does-it-mean-to-aspirate-an-injection https://askinglot.com/what-does-it-mean-to-aspirate-an-injec...