Complications related to venipuncture
Venipuncture is an invasive procedure because a needle is inserted through the skin to reach a vein. It is however a very safe procedure. Millions of venipunctures are performed in Australia every year. Venipunctures are performed by doctors, nurses or specially trained blood collectors called phlebotomists.
By far the most common complication of venipuncture is bruising at the site of the needle puncture. This usually appears within 24 hours and may range in size from a small spot to a large purple bruise. It is caused by blood leaking from the punctured vein out into the tissues just under the skin, which can be reduced by using finger pressure on the site for a minute or so after the venipuncture.
Bruising is more likely if the collection is difficult, if pressure is not maintained on the site for a minute or so after the venipuncture, if you are taking anti-clotting medicines such as aspirin or warfarin, you are an elderly person with fragile veins, or if you exercise your arm soon after the venipuncture for example by lifting heavy shopping bags.
While bruising is unsightly it is not dangerous and will slowly disappear over a few days or weeks, depending on how extensive it is. Large bruises may become tender for a few days because the cells that are involved in mopping up the bruise release substances that cause the area to become sore. This is uncommon but again not dangerous, it is part of the healing process. However if the tenderness is bothering you, you should contact the person or clinic where you had the venipuncture.
Very rarely a small artery, which contains blood at much higher pressure than in veins, will lie unusually close to or underneath a vein. In this situation the artery may be accidentally punctured at the time of venipuncture. If this happens you generally become aware of it within a few minutes because a painful deep swelling can be felt and sometimes seen near the area of the venipuncture. Tell the collector if this happens as it is necessary to apply firm pressure to the area for at least 5 minutes; and remember for next time. Almost inevitably you will develop extensive and sometimes spectacular bruising on the lower part of the arm over the next two to three days because the blood leaks to the underside of your arm with gravity. While this may appear dramatic it is not dangerous and will gradually disappear over a couple of weeks.
There are other rare complications of venipuncture but you have to be unlucky to suffer one of these. For example you may have a tiny branch of one of the sensory nerves of the arm actually running over the surface of the vein. Rarely the needle will hit this tiny nerve on the way into the vein. This may cause a short, sharp electric-shock type pain. This may be all that happens; however in some cases tingling type of pain may persist for one to four weeks, as the nerve heals. This is inconvenient and may be unpleasant but it eventually heals up.
Another rare complication of venipuncture is for a small clot (or thrombus) to form in the vein at the site of the venipuncture. This is noticeable as a small firm lump just under the skin at the venipuncture site. The lump may or may not be tender and will go away over a couple of weeks.
Finally, there is the possibility of infection developing at the site of the venipuncture. This is extremely rare and would be noticed as developing redness and pain at the site of the venipuncture. Most times discolouration and tenderness around the venipuncture site are the result of bruises healing but if you are worried contact the person or clinic where you had the blood collection done or visit your doctor.
