BLEEDING TIME
Screening coagulation tests for Bleeding Time
A bleeding time test determines how quickly your blood clots to stop bleeding. The test involves making small punctures in your skin. The test is a basic assessment of how well your blood platelets work to form clots. Platelets are tiny cell fragments that circulate in your blood. They’re the first cells to react to a blood vessel injury. They seal off the wound to prevent more blood from escaping. Determination of bleeding time recognizes vascular defect and platelet disorder. The latter is further confirmed through other tests described later. Prolonged bleeding time is generally found with thrombocytopaenia (platelet count <50000 platelets/µL) and where there is a platelet dysfunction. In case of von Willebrand’s disease, which is caused by a platelet defect combined with factor VIII deficiency, bleeding time is high with a normal platelet count.
Normal Range
Specimen
Performed on patient; no specimen necessary
Principle
DUKE METHOD
Duke method
Duke method is easy to perform and requires minimal equipment or laboratory skill.
Requirement
- Alcohol sponge
-Sterile lancet
- Filter paper (circular) or blotting paper
- Stopwatch or a watch with seconds hand
Note: Arrange all the necessary materials before starting the test. As the test is performed on the patient, you must approach the patient with proper bedside manner and must be well organized while performing the test. This improves public relations and builds confidence in the patient.
Procedure
1. Gently clean the earlobe with an alcohol sponge. Do not rub. Allow it to dry completely.
2. Hold a glass slide behind the earlobe for support. Make a deep puncture with a sterile lancet. Start the stopwatch and discard the glass slide. The blood should flow freely, without squeezing the earlobe.
3. Using a circular filter paper, blot the drop of blood coming out of the incision every 30 s. Do not allow the filter paper to touch the bleeding spot. Keep each subsequent drop a little further along the side of the filter paper; the drops become progressively smaller.
4. When bleeding ceases, stop the stopwatch.
5. Count the number of drops on the filter paper and multiply by 30 s.
6. Report to the closest minute.
Note: If the bleeding continues for more than 10 min, discontinue the test and apply pressure to the bleeding spot.
EXTRA INFO NOTES
Why do I need a bleeding time test?
Most people will never need a bleeding time test. You may need to have a bleeding test if you’ve been experiencing bleeding that won’t stop, especially from small incisions, punctures, or cuts.
Your doctor can choose from a number of tests to evaluate your platelet function. A bleeding time test is a common test to screen patients having prolonged bleeding times.
Abnormal results from a bleeding time test can be a sign that you need more in-depth testing to find the cause of your prolonged bleeding. It could mean you have an acquired platelet function defect, which is a condition that develops after birth and affects how well your blood platelets work. Your body may produce too many or too few platelets, or your platelets may not work properly.
Abnormal results could also indicate the following conditions:
- A blood vessel defect is any condition that affects how well your blood vessels transport blood through your body.
- A genetic platelet function defect is a condition present at birth that affects how well your platelets function. Hemophilia is one example of this type of defect.
- Primary thrombocythemia is a condition in which your bone marrow creates too many platelets.
- Thrombocytopenia is a condition that causes your body to produce too few platelets.
- Von Willebrand’s disease is a hereditary condition that affects how your blood coagulates (clots).
Tell your doctor about any medications you’re taking, including prescriptions, over-the-counter medicines, and vitamin and mineral supplements. Some medications, such as aspirin, can affect how well your blood clots.
Your doctor may instruct you to stop taking your medication a few days before your test. Follow your doctor’s instructions, but don’t stop taking any medication unless instructed to do so by your doctor.
On the day of your test, wear a short-sleeved shirt so that the healthcare provider can easily access your puncture site.
What are the risks associated with a bleeding time test?
Anytime your skin is broken, there’s a risk of excessive bleeding and infection. Since the purpose of the test is to make you bleed, some bleeding is a certainty.
However, because the test punctures are relatively shallow, the risk of excessive bleeding is minimal and complications are extremely rare.
Learning how long it takes your blood to clot can help your doctor determine if you have a bleeding disorder, such as hemophilia or von Willebrand’s disease.
A chronic disease can cause platelet dysfunction over a person’s lifetime, but medication and treatment can often manage this particular symptom.
Normal bleeding time is between one and five minutes. Results outside of that range could indicate a platelet defect and require further testing. Your doctor will analyze your test results and discuss any necessary additional testing with you.
What Abnormal Results Mean
Longer-than-normal bleeding time may be due to:
- Blood vessel defect
- Platelet aggregation defect (clumping problem with platelets, which are parts of the blood that helps the blood clot)
- Thrombocytopenia (low platelet count)
https://www.myvmc.com/investigations/blood-clotting-assessment-before-surgery/
https://www.medicine.mcgill.ca/physio/vlab/bloodlab/hemostasis_n.htm
https://labpedia.net/bleeding-time-bt/
Other Methods:
https://www.platelet-research.org/techniques-available/bleeding-time/
https://phlebotomygeeks.yolasite.com/resources/LAB%208%20BLEEDING%20TIME.pdf
APTT
https://practical-haemostasis.com/Screening%20Tests/aptt.html
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