Bleeding time

How the Test is Performed:
A blood pressure cuff is placed on the upper arm and inflated. Two incisions are made on the lower arm. These are about 10 mm (less than 1/2 inch) long and 1 mm deep (just deep enough to cause minimal bleeding ). The blood pressure cuff is immediately deflated. Blotting paper is touched to the cuts every 30 seconds until the bleeding stops. The length of time it takes for the cuts to stop bleeding is recorded.

How to Prepare:
Adults:
No special preparation is necessary.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:



How it Feels:
The incisions are very shallow and feel like a scratch.

Risks:
There is a very slight risk of infection (because the skin is broken). Excessive bleeding is rare.

Why this Test is Performed:
This test is useful for detecting bleeding tendencies.

Normal Values:
The bleeding stops within 1 to 9 minutes. This may vary from lab to lab, depending on how the test is measured.

Abnormal Results:
Prolonged bleeding time may indicate:

  • a vascular (blood vessel) defect
  • a platelet function defect (see platelet aggregation)
  • thrombocytopenia

Drugs that may increase bleeding times include dextran, indomethacin, and salicylates (including high doses of aspirin).

Additional conditions under which the test may be performed:



Cost:
The estimated cost is $25.

Special Considerations:
The bleeding time test is used to evaluate the vascular (blood vessel) and platelet factors associated with hemostasis ( blood clot formation). When vascular injury occurs, the first hemostatic response is a spastic contraction of the lacerated vessels. Next, platelets adhere to the wall of the vessel at the area of laceration in an attempt to plug the hole. The failure of either process results in a prolonged bleeding time.