Blood vessels that have thinner walls that are more likely to collapse when blood is withdrawn during a venipuncture are called veins.
Differently form arteries, veins are blood vessels with thin, less muscular walls. Veins have thinner walls because the blood pressure in them is much lower.
So, as a result of common intravenous injections (such as venipuncture), collapsed veins might occur. Veins are then temporarily blocked.