Two attempts at drawing blood should be made by a technician or phlebotomist when performing venipuncture.
Normally, a phlebotomist will try to hit the vein and collect blood at the first attempt, however, that doesn’t always happen. There are many reasons why the technician may not collect blood at the first go. Some of these may be due to the phlebotomist’s technique, location or level of difficulty of the person’s vein, patient moving their arm, or dehydration.
From my experience, I only have two chances at drawing blood from an individual. If at the second attempt I haven’t collected blood, then I should let another phlebotomist try. Usually, when you can’t get blood, another technician will.
There may be times when a phlebotomist may have to try more than twice as in the case when there are a limited number of technicians available. Also, the number of attempts may vary slightly from one lab to another or one country to another.
How many times can a patient be stuck? About 4 sticks is a good place to stop. If I have attempted twice and another phlebotomist has attempted twice and we have not been successful at drawing blood, then the patient should be allowed to leave and return another day to try again.
I have drawn blood from individuals before, though, who insisted that I continued until I found blood. These persons are usually the ones with difficult veins and they are aware of it and don’t mind, although not all of them would insist.
The general rule, though, is about 4 sticks. Of course, there are instances like at the hospital or in an emergency when a person may be stuck more than 4 times in order to get blood. Also, the number of times may vary from place to place and country to country.
Read Why Does a Blood Test Needs Repeating.
Which areas must be avoided for venipuncture?
There are several venipuncture sites that are not suitable for drawing blood. They are as follows:
- Underside of the wrist. Do not draw blood from there. If blood is drawn there, it is a last resort and is done by an experienced professional.
- Veins in the foot and angle are only a last resort. Only personnel who are trained and have experience should venture there.
- Extensive scaring from burns or surgery.
- The upper extremity on the side that a mastectomy was performed.
- Hematomas. A venipuncture should not be performed on a hematoma. Try an alternate vein or the other arm.
- Cannular, fistula, or vascular graft.
- Edematous areas. Tissue fluid may contaminate sample and can alter test results.
- Areas with infection.
- IV sites. Draw blood from the other arm. If the other arm is not available then draw blood from below the IV. If above the IV is the only option, then turn of the IV infusion for about 5 minutes before performing venipuncture. Get permission from the doctor or nurse.
There is a possibility that the sample may be contaminated. Document that the sample was drawn above an IV site and how long the IV infusion was turned off for.
Drawing blood from arm versus hand
The best site for venipuncture is the arm, using either the median cubital or cephalic veins found there. The other option is the basilic vein, which is usually used when the others are not accessible or available.
Many times, arm veins are going to be easy to find since they are usually visible on most adults. At other times, they will be difficult depending on how deep they are and how much muscular or fat tissue that is surrounding them.
Dorsal hand veins are another option if finding a vein in the arm proves fruitless. Most times, hand veins are going to be very visible and easy to locate. However, there are those occasions when nothing will be seen. I wrote an article recently sharing tips and tricks to implement when faced with difficult veins. Click here to go check it out.
It’s easier to draw blood from the arm than the hand. However, a certain equipment (butterfly) may be easier to use in the hand than in the arm. Most often, the evacuated tube system is used in the arm while the syringe and needle or butterfly system in the hand.
Rolling veins occur more frequently in the hand than in the arm.
Is venipuncture a sterile procedure?
The tools used to perform a venipuncture are all sterile and safe. The procedure is designed to protect and keep the patient and technician safe. There is nothing to worry about.
A venipuncture can only be performed with sterile equipment. That ensures that the needle that enters the vein doesn’t introduce any microbes into the blood or to the surrounding tissue and cause an infection.
The venipuncture site must also be cleaned with alcohol and allow to air dry before inserting the needle into vein.
When the procedure is done a sterile bandage is placed on the venipuncture site to protect it.
A used needle MUST NOT be used to perform a venipuncture. If you have inserted a needle into a vein and for some reason you pull it out, you SHOULD NOT insert it into the vein a second time. Discard it and use a new needle.
When do you remove the tourniquet during a blood draw?
Remove the tourniquet once blood has started to flow into the tube. The tourniquet is used to help make the veins more visible or palpable. It should remain on the arm for about a minute to two minutes but not more than two minutes.
That will allow for enough time to locate veins and draw blood. Keeping the tourniquet on for longer will cause hemoconcentration.
Once you have inserted the needle and blood has began to flow into the collection tube, the tourniquet can be released. The vacuum in the tube will assist in filling it up.
There are people with really good veins that probably don’t even need a tourniquet. Those veins are above the skin and very visible and palpable. The tourniquet can be released in under a minute.
Also, don’t remove the needle from the vein while the tourniquet is on. The tourniquet must be released first before removing the needle.
What angle do you draw blood?
The insertion needle should be at a 15 to 30 degree angle with the arm. That position will ensure less pain and injury to the patient. When inserting the needle, maintain the 15 to 30 degree angle and swiftly but gently pierce the skin.
Do not jerk the patient with the needle or use arm force to insert it into the vein. That will hurt the patient or in their own words, they will tell you, “You prick me hard!” Use the wrist for a better maneuver and almost a painless entry.
I have found that when I use my wrist to insert the needle into the vein, the patient has a better experience and feels less pain. That’s when you will hear them say, “I didn’t feel anything!”
Remember to taut the skin and anchor the vein before inserting the needle. That will keep the vein from rolling, the skin from moving, and help you achieve a clean venipuncture.
How long does it take for water to hydrate your veins?
It takes about 20 minutes and sometimes less for water to hydrate your veins for a blood test. If you are dehydrated it will take longer than 20 minutes for the water you have drank to help make veins visible or palpable.
I have had difficulty finding a vein when attempting to draw blood from several individuals in the past, and after being unsuccessful in locating a vein, I will suggest to the person to drink some water. After about 10 to 15 minutes I will assess the person’s vein and will find one and draw blood.
Water can work really fast in helping veins to show up sometimes. The key is to be well hydrated before the venipuncture so that the phlebotomist can find your vein.
How much water should you drink before getting blood drawn? Drink 2 to 4 glasses before doing the blood test. The amount of water you drink will vary from person to person depending on many factors like your size for example.
A person who weighs 200 pounds will probably need more water to be hydrated than a person who weighs 90 pounds. Drink the amount of water that works for you.
Also, the amount you drink will depend on the time of day you are doing the blood test. If you are doing the blood test in the early hours of the morning, you will drink a couple glasses before the procedure. But if you are doing the venipuncture later in the day, like in the afternoon, then you would have probably drank a lot of fluids by then.
That’s what happens with a fasting blood test and a non-fasting blood test. The fasting blood test is usually done early in the morning, while the non-fasting blood test can be done anytime.
If you are drinking the recommended amount of water per day based on your age or weight, then you may not even need to worry about your veins being hydrated, because they would have already been well hydrated.