|
Bleeding time
Definition
Bleeding time is a blood test that looks at how fast small blood vessels in the skin close to stop you from bleeding.
How the Test is Performed
A blood pressure cuff is inflated around your upper arm. While the cuff is on your arm, the health care provider makes two small cuts on the lower arm. They are just deep enough to cause a tiny amount of bleeding.
The blood pressure cuff is immediately deflated. Blotting paper is touched to the cuts every 30 seconds until the bleeding stops. The health care provider records the time it takes for the cuts to stop bleeding.
How to Prepare for the Test
Certain medications may change the test results. Always tell your doctor what medications you are taking, even over-the-counter drugs. Drugs that may increase bleeding times include dextran, nonsteroidal anti-inflammatory drugs (NSAIDs), and salicylates (including aspirin).
Your doctor may tell you to stop taking certain medicines a few days before the test. Never stop taking medicine without first talking to your doctor.
How the Test Will Feel
The tiny cuts are very shallow. Most people say it feels like a skin scratch.
Why the Test is Performed
This test helps diagnose bleeding problems.
Normal Results
Bleeding normally stops within 1 to 9 minutes. However, values may vary from lab to lab.
What Abnormal Results Mean
Longer-than-normal bleeding time may be due to:
- Blood vessel defect
- Platelet aggregation defect
- Thrombocytopenia (low platelet count)
Additional conditions under which the test may be performed:
- Acquired platelet function defect
- Congenital platelet function defects
- Primary thrombocythemia
- Von Willebrand's disease
Risks
There is a very slight risk of infection where the skin is broken. Excessive bleeding is rare.
References
Schmaier AH. Laboratory evaluation of hemostatic and thrombotic disorders. In: Hoffman R, Benz EJ Jr., Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2008:chap 122.
Schafer A. Hemorrhagic disorders: Approach to the patient with bleeding and thrombosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 178.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
