Bleeding time

Bleeding time is a medical test done on someone to assess their platelets function. It involves making a patient bleed, then timing how long it takes for them to stop bleeding using a stopwatch or other suitable devices. The term template bleeding time is used when the test is performed to standardized parameters. The bleeding time test is a method indicated when other more reliable and less invasive tests for determining coagulation are not available. However, it remains the most reliable way of assessing clinical bleeding in patients with uremia. Historically it was indicated whenever physicians needed information about platelet activation. It involves cutting the underside of the subject's forearm, in an area where there is no hair or visible veins. The cut is of a standardized width and depth, and is done quickly by an automatic device. A blood pressure cuff is used above the wound, to maintain venous pressure at a specified value. The time it takes for the bleeding to stop (i.e. the time it takes for a platelet plug to form) is measured. Cessation of bleeding can be determined by blotting away the blood every several seconds until the site looks "glassy". The IVY method is the traditional format for this test. While both the IVY and Duke's method require the use of a sphygmomanometer, or blood pressure cuff, the IVY method is more invasive than the Duke method, utilizing an incision on the ventral side of the forearm, whereas the Duke method involves puncture with a lancet or special needle. In the IVY method, the blood pressure cuff is placed on the upper arm and inflated to 40 mmHg. A lancet or scalpel blade is used to make a shallow incision that is 1 millimeter deep on the underside of the forearm. A standard-sized incision is made around 10 mm long and 1 mm deep. The time from when the incision is made until all bleeding has stopped is measured and is called the bleeding time. Every 30 seconds, filter paper or a paper towel is used to draw off the blood. The test is finished when bleeding has stopped.