What is a bleeding time test?

A bleeding time test determines how quickly your blood clots to stop bleeding. The test involves making small punctures in your skin.

The test is a basic assessment of how well your blood platelets work to form clots.

Platelets are tiny cell fragments that circulate in your blood. They’re the first cells to react to a blood vessel injury. They seal off the wound to prevent more blood from escaping.

Most people will never need a bleeding time test. You may need to have a bleeding test if you’ve been experiencing bleeding that won’t stop, especially from small incisions, punctures, or cuts.

Your doctor can choose from a number of tests to evaluate your platelet function. A bleeding time test is a common test to screen patients having prolonged bleeding times.

Abnormal results from a bleeding time test can be a sign that you need more in-depth testing to find the cause of your prolonged bleeding. It could mean you have an acquired platelet function defect, which is a condition that develops after birth and affects how well your blood platelets work. Your body may produce too many or too few platelets, or your platelets may not work properly.

Abnormal results could also indicate the following conditions:

  • A blood vessel defect is any condition that affects how well your blood vessels transport blood through your body.
  • A genetic platelet function defect is a condition present at birth that affects how well your platelets function. Hemophilia is one example of this type of defect.
  • Primary thrombocythemia is a condition in which your bone marrow creates too many platelets.
  • Thrombocytopenia is a condition that causes your body to produce too few platelets.
  • Von Willebrand’s disease is a hereditary condition that affects how your blood coagulates (clots).

Tell your doctor about any medications you’re taking, including prescriptions, over-the-counter medicines, and vitamin and mineral supplements. Some medications, such as aspirin, can affect how well your blood clots.

Your doctor may instruct you to stop taking your medication a few days before your test. Follow your doctor’s instructions, but don’t stop taking any medication unless instructed to do so by your doctor.

On the day of your test, wear a short-sleeved shirt so that the healthcare provider can easily access your arm.

A healthcare provider performs the test by following these steps:

  1. They clean the puncture site with an antiseptic to minimize the risk of infection.
  2. They place a pressure cuff around your upper arm and inflate it.
  3. Next, they make two small cuts on your lower arm. These will be deep enough to cause slight bleeding. You might feel a slight scratch when they make the cuts, but the cuts are very shallow and shouldn’t cause much pain.
  4. They remove the cuff from your arm.
  5. Using a stopwatch or timer, they blot the cuts with paper every 30 seconds until the bleeding stops. They record the time it takes for you to stop bleeding and then bandage the cuts.

Usually, if the cuts continue to bleed after 20 minutes, the healthcare provider notes that the bleeding time was over 20 minutes.

Anytime your skin is broken, there’s a risk of excessive bleeding and infection. Since the purpose of the test is to make you bleed, some bleeding is a certainty.

However, because the test punctures are relatively shallow, the risk of excessive bleeding is minimal and complications are extremely rare.

Learning how long it takes your blood to clot can help your doctor determine if you have a bleeding disorder, such as hemophilia or von Willebrand’s disease.

A chronic disease can cause platelet dysfunction over a person’s lifetime, but medication and treatment can often manage this particular symptom.

Normal bleeding time is between one and eight minutes. Results outside of that range could indicate a platelet defect and require further testing. Your doctor will analyze your test results and discuss any necessary additional testing with you.