Bleeding time test is a basic test of hemostasis (the clotting or ceasing of bleeding). It shows how well platelets coordinate with blood vessel walls to create blood clots.
Bleeding time test is conducted to detect defects of platelets, like Von Willebrand's disease. The test enables determine individuals who have disorders in the functioning of their platelet. This is the potential of blood to clot after a trauma or wound. Normally, platelets interact with the walls of blood arteries to from a blood clot.
There are several factors in the clotting mechanism, and they are originated by platelets. The bleeding time test is basically performed on patients manifesting a track record of continuous bleeding after cuts, or who have a family background of bleeding disorders. The bleeding time test is also often performed as the initial step to analyze a patient's normal bleeding response during and post surgery. However, in patients without any history of bleeding abnormalities, or who are not on any anti-inflammatory medicines, the bleeding time test is not generally required.
Before performing the test, patients should be inquired about what drugs they may be taking. Some drugs will adversely affect the reports of the bleeding time test. These drugs include diuretics, anticancer drugs, anticoagulants, aspirin, sulfonamides, nonsteroidal anti-inflammatory drugs etc. The test may also be influenced by anemia (a deficiency in red blood cells). Since the taking of aspirin or related drugs are the most common cause of prolonged bleeding time, no aspirin should be taken two weeks prior to the test.
There are four ways to conduct the bleeding test. The Ivy method is the most conventional process for this test. In the Ivy method, the blood pressure cuff is wrapped on the upper arm to inflate it to 40 mM Hg. A scalpel blade or lancet is facilitated to create a stab wound on the underside of the forearm. An automatic, spring-based blade tool is generally facilitated to create a standard-sized cut. This area is chosen for stabbing so that any superficial or visible veins are not cut. These veins, based on their size, may have long stretched bleeding period, especially in people with bleeding defects. The bleeding time is considered starting from when the cut is made until the entire bleeding has ceased. In every small interval of time, i.e. in few seconds, the blood is wiped off using a filter paper or a paper towel. The test is completed with the stopping of bleeding entirely.
Template, modified template, and Duke ways are other 3 processes of conducting the bleeding test. The template and modified template methods are different versions of the Ivy method. A blood pressure cuff is facilitated and the skin on the forearm is stabbed similar to Ivy method. A template is placed on the area to be stabbed and two incisions are created in the forearm facilitating the template as a site guide.
The prominent difference between the template and the improved method is the stretch of the cut made.
For the Duke method, a chip is made in an ear lobe or a fingertip is pricked to withdraw blood. As in the Ivy method, the test time is calculated from the start of bleeding until bleeding is fully ceased.
The draw back of the Duke method is that the pressure on the blood veins in the stabbed site is not even and the outcomes achieved are less accurate. The benefits of Duke method is that no mark is left out post test. The other processes may result in a small, hairline scar where the stab was made. However, this is entirely a cosmetic concern.
There is no particular preparation required of the individual for this test. The location to be cut should be wiped with an alcohol pad to kill bacteria at the wound site. The alcohol must be discarded prior to the stabbing of arm as alcohol will adversely influence the tests reports by inhibiting clotting.
If the bleeding time is longer due to several factors or diseases, further testing can also be recommended to determine the accurate reason of the bleeding disorder.
A normal bleeding duration for the Ivy method is almost five minutes from the time of the cut until all the bleeding stops. Some texts stretch the normal period to eight minutes. Normal values for the template method stretches up to eight minutes, whereas for the modified template methods, extension up to 10 minutes is quite normal. In the Duke method the expected bleeding time is three minutes.
A bleeding time that is more than normal is not a normal result. The test should be ceased if the patient hasn't curbed bleeding by 20-30 minutes. Bleeding time is longer when the normal working of platelets is defective, or if there are low levels of platelets in the blood.
A longer-than-normal bleeding stretch of time can signal that one of many disorders in hemostasis is there, encompassing platelet dysfunction, severe thrombocytopenia, Von Willebrand's disease, vascular defects, or any other abnormalities.