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Bleeding time is a medical test performed to assess the efficiency of a patient's platelet function and his body's blood-clotting mechanism. In general, a physician will use an automatic device to administer a small cut in the patient's body to produce a little bleeding, and the individual's bleeding time is the amount of time it takes for the wound to completely stop bleeding. The Duke method and Ivy method are the two major approaches to performing this test, the latter being the more common of the two. While the Duke method involves pricking the patient with a needle or similar device, the Ivy method is relatively more invasive, involving an incision to the forearm. While certain drugs may artificially increase bleeding time if taken shortly before the test, abnormal results can indicate conditions such as thrombocytopenia and von Willebrand disease.
The Duke method is less commonly used. After cleaning the area with alcohol, the physician will prick the patient's fingertip or earlobe with a specialized needle or lancet, usually around 0.1-inches-deep (3 to 4 mm). The usual bleeding time for the Duke method is around one to three minutes.
Under the Ivy method, the physician will use a spring-loaded scalpel blade or lancet to create an incision on the patient's forearm, typically on the underside where there are no visible veins. The standard size for the cut is usually 0.3-inches-long (10 mm) and .03-inches-deep (1 mm), and a sphygmomanometer, or blood pressure cuff, is placed anywhere above the wound in order to maintain a standardized blood pressure in the veins. A paper towel will be used to clear the area of blood approximately every 30 seconds until the bleeding has completely stopped. The normal bleeding time for the Ivy method is anywhere from two to nine minutes. In all cases, bleeding must be manually stopped if the patient bleeds for more than 20 minutes.
Several drugs can lead to prolonged bleeding time in patients who have taken them shortly before the test. This can include aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) and antihistamines. A patient should report to the physician any medications that he or she is on prior to taking the test, including over-the-counter drugs.
Thrombocytopenia refers to an abnormally low platelet count, leading to decreased clotting ability for the body. The condition may derive from a variety of causes, such as medication that may be affecting platelet production or primary diseases that lead either to the destruction or decreased production of platelets. The platelets of patients who have von Willebrand disease have compromised coagulation ability due to a deficiency of the von Willebrand factor, a protein essential to the process of platelet adhesion. Von Willebrand disease is most commonly inherited, but can be acquired as an offshoot of another primary condition in rarer cases.
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