Bleeding time is a test used to determine how quickly your blood clots to stop you from bleeding. The test involves making small, superficial cuts on your skin similar to light scratches.
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 are the first cells to react to a blood vessel injury. They seal off the wound to prevent more blood from escaping.
You may need to undergo a bleeding test if you’ve been experiencing bleeding that won’t stop, especially after receiving small incisions, punctures, or cuts.
Abnormal results of a bleeding time test could indicate:
- acquired platelet function defects—conditions that develop after birth and affect how well your blood platelets work. Your body may produce too many or too few platelets or they may not work properly
- blood vessel defect—any condition that affects how well your blood vessels transport blood through your body
- hereditary platelet function defects—conditions present at birth that affect how well your platelets function. Hemophilia is an example
- primary thrombocythemia—a condition in which your bone marrow creates too many platelets
- thrombocytopenia—a condition that causes your body to produce too few platelets
- Von Willebrand’s disease—the most common hereditary condition that affects how your blood coagulates (clots)
Tell your doctor about any medications you are taking, including prescriptions, over-the-counter medicines, and vitamin and mineral supplements. Some medications (especially 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 do not stop taking any medication unless your doctor tells you to do so.
On the day of your test, wear a short-sleeve shirt so that the technician can access your arm.
A nurse or technician will perform the test. He or she will put antiseptic on your arm to minimize the risk of infection.
A pressure cuff will be inflated around your upper arm. Next, the technician will make two small cuts on your lower arm. These will be deep enough to cause slight bleeding.
The cuff will be taken off your arm and the technician will blot the cuts with paper every 30 seconds until the bleeding stops. The technician will record the time it takes for you to stop bleeding and will then bandage the cuts.
Anytime your skin is broken, you run the 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 scratches are so shallow, the risk of excessive bleeding is minimal and complications are extremely rare.
Your doctor will be checking how long it takes for your blood to clot. This can help the doctor determine if have a bleeding disorder, such as hemophilia or von Willebrand’s disease.
Normal bleeding time is between one and eight minutes. Results outside of that range could indicate a platelet defect and will require further testing.