A bleeding time test is a standardized medical procedure for determining platelet function.
The physician uses a scalpel to make a precise incision 10mm long and 1mm deep. The cut is made on the underside of the forearm, away from any hair or visible veins. A blood pressure cuff is used to maintain a constant and standard blood pressure of 40mmHg through the patient's veins during the test. Blood is blotted every 30 seconds until the cut takes on a glossy appearance showing the formation of a platelet plug, and is completed when bleeding has completely stopped. A result of less than 9 minutes and 30 seconds is normal, but the actual time usually ranges widely from 2 to 9 minutes.
An alternative method is to prick the patient's fingertip or earlobe with a needle. The normal time for bleeding to stop with this method is 1 to 3 minutes.
The bleeding time test is usually preferred to other methods of determining whether a patient has a coagulopathy, such as blood tests, because bleeding time is solely a result of platelet function. It could, however, either mean a lack of platelets, or that the platelets aren't functioning properly.