Phlebotomist: Needle Positioning
A common cause of a blood draw failure is improper needle position. An experienced phlebotomist is able to identify visual cues that can help to determine if a needle is correctly positioned in the vein. There are five different needle positions that can affect blood flow and impede blood collection.
Bevel Against The Vein Wall
If the needle bevel is up against the upper of lower wall of the vein blood flow can be affected. The needle angle is usually the cause of this problem and can be easily fixed by changing the angle. An angle that is too shallow can cause the needle to come into contact with the upper wall; an angle that is too steep can cause the needle to come into contact with the lower wall. This commonly occurs when a needle is inserted in a bend in a vein or at a point where a vein goes deeper into the skin. Unfortunately, all of these situations are difficult to detect. A highly skilled phlebotomist will likely try to reestablish blood flow by releasing the vacuum pull on the vein and retract the needle slightly. If blood flow is not established after these modifications, the problem is likely due to the placement of the bevel and the vein wall.
Needle Too Deep
If the needle is inserted too deeply it can very easily penetrate all the way through the vein. This often happens if the needle angle is too steep, or if the tube holder is not steady as a tube is pushed onto the needle. If this occurs sometimes slightly withdrawing the needle may reestablish blood flow. A hemotoma can form if the needle position is not corrected quickly.
Needle Not Deep Enough
If a needle is not completely inserted through a vein wall, the flow of blood will be very slow. Blood flow can be improved by gently pushing the needle forward into the vein. A hematoma can also form from partial needle insertion because blood can leak from the vein into the surrounding tissue.
Needle Beside The Vein
Sometimes the needle can slip to the side of a vein instead of into the vein. This occurs more often if a vein is not anchored well with the phlebotomist's thumb during needle insertion. The needle may end up beside and under the vein. Should this occur, a phlebotomist should try and preserve the vacuum, withdraw the needle slightly, anchor the vein well, and redirect the needle into the vein. Never move the needle in a lateral direction to find a vein.
Undetermined Needle Position
Sometimes the position of a needle can not be determined visually and the phlebotomist will have to use her finger to relocate the vein. Once the vein is relocated, the needle should be relocated into it.