What to Expect with Blood Tests

What To Expect Before Blood Tests

• Many blood tests don't require any special preparation and take only a few minutes.
  
  
• Other blood tests require fasting (not eating any food) for 8 to 12 hours before the test. Your doctor will tell you how to prepare for your blood test(s). 

What To Expect During Blood Tests

• Blood usually is drawn from a vein in your arm or other part of your body using a needle.
  
  
• The person who draws your blood might tie a band around the upper part of your arm or ask you to make a fist. Doing this can make the veins in your arm stick out more, which makes it easier to insert the needle.
  
  
• The needle that goes into your vein is attached to a small test tube. The person who draws your blood removes the tube when it's full, and the tube seals on its own. The needle is then removed from your vein.
  
  
• If you're getting a few blood tests, more than one test tube might be attached to the needle before it's withdrawn.
  
  
• Some people get nervous about blood tests because they're afraid of needles. Others don't want to see blood leaving their bodies. If you're nervous or scared, it can help to look away or talk to someone to distract yourself. You might feel a slight sting when the needle goes in or comes out.
  
  
• Drawing blood usually takes only a few minutes.

What To Expect After Blood Tests

• When the needle is withdrawn, you'll be asked to apply gentle pressure with a piece of gauze bandage to the site. This helps to stop the bleeding and may help prevent swelling and bruising.
  
  
• Make sure that you do not bend your arm, as this may cause bruising.
  
  
• Hold pressure until you are asked to remove your hand. The phlebotomist will check for continued bleeding and apply a bandage if it has stopped. You may want to keep a bandage on for a few hours.
  
  
• If bleeding occurs, elevate your arm and apply pressure to the bandage for at least five minutes.
  
  
• If you develop a bruise, apply ice wrapped in a towel or cloth to the area for 15-30 minutes several times a day for the first day. Warm, moist heat can be used instead of ice after the first day. If you experience more than minor discomfort after the first day, you may wish to call your physician for advice.
  
  
• Usually, you don't need to do anything else after a blood test. Your doctor will get the results. It's important that you follow up with your doctor to discuss your test results.

What Are the Risks of Blood Tests?

• The main risks of blood tests are discomfort and bruising at the site where the needle is inserted. These issues usually are minor and go away shortly after the tests are done.

Reference: http://www.nhlbi.nih.gov/health/health-topics/topics/bdt/with.html