Bleeding Time (BT)

What sample is needed for Bleeding Time (BT)?

1. This test is performed on the patient while they are in the lab.
2. No preparation is necessary.
3. The template (Meilke) method is the most common and considered the most accurate.
   1. This template is a modified version of the Ivy method.
   2. The template method gives 1 mm deep incisions.
   3. A small, disposable, spring-driven lancet produces a 5 mm long and 1 mm deep incision, resulting in minimal pain and no scar formation.
4. Ivy and Duke’s methods were used in old times.

What are the precautions for bleeding time (BT)?

1. This test should be avoided in a patient with a low platelet count.
2. A patient with aspirin may have a false positive (raised value).
3. Avoid in patients with keloid formation or senile skin changes.
4. Avoid in patients who have undergone mastectomy or axillary lymph node dissection.
5. Avoid uncooperative patients.
6. Extreme body temperature gives false results.
   1. High body temperature prolonged the result.
   2. Low body temperature lowers the result.
7. Avoid and take the history of drugs that may prolong the result, like patients on anticoagulant therapy, use of salicylates,  antibiotics, streptokinase, nonsteroidal anti-inflammatory drugs, and warfarin.

What are the indications for Bleeding Time (BT)?

1. Bleeding time (BT) is the best test to evaluate the platelets’ function and structural abnormalities.
2. This test is done to evaluate vascular and platelet factors.
   1. Bleeding time gives a better idea of platelet function, such as the platelet count.
3. This may be done preoperatively to rule out the possibility of bleeding, for example, in patients undergoing tonsillectomy.
   1. But this may not be a routine presurgical procedure.
4. This test is used to evaluate the stability of the patient’s hemostatic mechanism.
5. A bleeding test may be done to detect the presence of various coagulation disorders.
6. This may be advised to monitor the treatment of active hemorrhage in patients with prolonged bleeding time due to von Willebrand disease, severe anemia, and congenital platelet functional abnormalities.
7. Bleeding time (BT) is the best test for screening uremic patients.
8. It is advised in a history of excessive bleeding and normal bleeding time (BT) before:
   1. Extraction of the tooth.
   2. Circumcision.
   3. Childbirth.
   4. Tonsillectomy.
9. Summary of bleeding time indications:
   1. Platelet function disorders.
   2. Vascular defects.
   3. Effects of drugs.
   4. Von Willebrand disease.

What are the advantages of Bleeding Time (BT)?

1. This test is used to differentiate Von Willebrand’s disease from mild hemophilia.
2. This test is useful as a part of the workup for coagulation disorders in patients with H/O excessive bleeding during dental extraction, tonsillectomy, circumcision, and childbirth, even with a normal platelet count.
3. The bleeding time (BT) is used to detect any abnormalities in platelet number or function.

What are the disadvantages of Bleeding Time (BT)?

1. No use in doing bleeding time (BT) in case of decreased platelets (<100,000/cmm), as bleeding time (BT) is usually prolonged.
2. Normal bleeding time (BT) does not rule out significant platelet abnormalities in cases of clinical suspicion. In such cases, a platelets aggregation test should be performed, and check the fibrinogen level.
3. This test is unable to predict excessive surgical bleeding.
4. Bleeding time is a crude and not a good screening test for bleeding during surgery.
5. The bleeding test will neither predict the likelihood of bleeding nor the possibility of not bleeding.
6. The bleeding time prick is 9 mm long and 1 mm deep, which may lead to scar formation.
7. This test is not recommended to predict bleeding in myeloproliferative disorders and neonates receiving nonsteroidal anti-inflammatory drugs.
8. Prolonged bleeding time may not necessarily lead to prolonged bleeding.
9. Not recommended for predicting bleeding in case of myeloproliferative diseases or neonates receiving NSAIDs (Non-steroidal anti-inflammatory drugs).

How will you define Bleeding Time (BT)?

1. Bleeding time is the functional test of primary hemostasis.
2. This test diagnoses bleeding problems related to the abnormalities of:
   1. Platelet functions. Platelets respond to vascular injury.
   2. Vascular response to injury.
   3. Blood vessel elasticity also influences the bleeding time.
   4. The ability of the blood vessels to constrict.
3. Bleeding time is the best single screening test for acquired causes, like uremia or congenital functional or structural disorders of platelets.
4. Bleeding time depends upon:
   1. Platelet functions.
   2. Platelet count.
   3. Vascular ability to stop bleeding.

What are the important facts about Bleeding time (BT)?

1. In the case of platelets 100,000/cmm, the bleeding time is usually normal, but when it is <100,000/cmm, the bleeding time is prolonged, and there may be a correlation between the count and severity of thrombocytopenia.
2. It measures the length of time bleeding continues after the standardized incision is made in the skin.
3. The bleeding time is usually abnormal in congenital defects, such as Glanzmann’s thrombasthenia.
4. Bleeding time is also abnormal in uremia, and the myeloproliferative syndrome is an acquired functional abnormality.
   1. 50% of uremic patients show thrombocytopenia.
   2. Bleeding in uremia is not usually seen unless the bleeding time is elevated, but some studies don’t agree with this hypothesis.
   3. Uremic bleeding can be treated by fresh frozen plasma, cryoprecipitate, or desmopressin (DDAVP = 1-deamino-8-arginine-vasopressin).
5. Some drugs, like aspirin, also interfere with platelet functions and prolong the bleeding time.
   1. After a single dose of aspirin, prolonged bleeding time is observed even within 2 hours, with maximum effect typically occurring after about 24 hours.
6. Aspirin permanently affects the function of platelets in circulation.
7. Platelets’ lifespan is 7 to 10 days, and approximately 10% of the platelets are replaced daily.
8. After stopping the aspirin, it takes 2 to 3 days, and the range is 1 to 8 days to produce a sufficient number of unaffected platelets, bringing the elevated bleeding time back into the normal range.
9. Bleeding time may be abnormal in cases of capillary fragility.
10. Bleeding time is typically normal in cases of hemophilia and vitamin K or fibrinogen deficiencies, but it is abnormal in severe cases.
11. Generally, if the bleeding time exceeds 1.5 times the normal limit, the risk of excessive bleeding during surgery increases.
12. Bleeding time is basically a screening test for:
    1. Disorders of platelet function and numbers.
    2. The integrity of the vascular wall.

What is the value of the effect of various blood coagulation factors on bleeding?

What is the importance of platelets?

Platelets:

1. Platelet abnormalities are divided into two groups:
   1. Quantitative when there is an abnormal platelet count.
   2. Qualitative, where the platelets’ functions are abnormal.

How will you predict bleeding due to the function of platelets?

1. How to predict whether a patient may bleed because of platelet abnormalities:
   1. If there is a history of aspirin intake or other drugs, it will give rise to thrombocytopenia.
   2. History of oozing or blood loss due to minor oral or dental surgery, during menses, or easy bruising.
   3. In case of a low platelet count.

What are the Quantitative platelet abnormalities?

What are the stages in the blood coagulation phenomenon?

1. First hemostatic response:
   1. For vascular injury, the initial hemostatic response involves the contraction of blood vessels.
   2. The next phase is the adherence of platelets to the injured vessel and the formation of plugs in the damaged area.
2. Vasospasm:
   1. Vasoconstriction (vasospasm). This is controlled by local, humoral, and neuronal factors.
   2. Initially, there is vasoconstriction, followed by vasodilation, which facilitates the influx of inflammatory cells.
3. Formation of platelet plug:
   1. There are granules discharged from the platelets.
   2. The platelets aggregate into clumps or plugs.
   3. Then release chemical mediators.
   4. Platelets are attracted to the site of endothelial injury within 15 to 20 seconds.
   5. Platelets make plug formation.
4. Blood coagulation factors:
   1. These coagulation factors are activated, helping to facilitate the coagulation process.
5. Vasculature: There is vasoconstriction (vasospasm).

What are the functions of the platelets?

1. The platelet membrane is composed of glycoproteins that determine the interaction between platelets and their external environment.
2. The binding of fibrinogen to the platelets leads to platelet aggregation.
3. Adherent platelets produce histamine, and serotonin will lead to vasoconstriction.

What are the steps in the bleeding control mechanism?

1. Activation of coagulation factors.
2. Formation of a clot.
3. Clot retraction.
4. Clot dissolution (fibrinolysis).

5. Failure of any of the above factors leads to prolonged bleeding.
6. If the blood vessels have increased fragility, it will also lead to a prolonged bleeding time, as seen in old age or a patient with a capillary defect.
7. The coagulation system does not affect blood vessel constriction and platelet adherence (Intrinsic and extrinsic pathways).
8. This test is a sensitive measure of platelet function and the elasticity of blood vessels.

What is the normal platelet count?

1. Normal platelet count is 140,000 to 340,000/cmm.
2. Platelets around 20,000/cmm may have a major episode of hemorrhage.
3. It is a crude bio-assay but has become a reliable and sensitive platelet function test by careful standardization.

What are the critical values?

1. Platelet counts less than 50,000/cmm may lead to prolonged bleeding times.
2. Platelets may be roughly estimated from the peripheral smear, where you will find 10 to 20 platelets /high-power field or 1 platelet/20 RBCs in the normal range.
3. A bleeding time of more than 10 minutes carries a risk of excessive bleeding; when it is 15 to 20 minutes, the risk of bleeding may increase.

What are the normal values of bleeding time (BT)?

• Bleeding time normal: 2 to 7 minutes
  • Borderline: 7 to 11 minutes.
  • Abnormal value: 10 to 15 minutes
• Duke ear lobe method = 1 to 3 minutes

Source 2

• Ivy method = 1 to 9 minutes
  • Prolonged bleeding time may be repeated to confirm it. Because if sometimes the large-caliber blood vessel is punctured, then the bleeding time will be prolonged.

Another source

• Adult, elderly, and pregnant = Template method = 2.0 to 8.5 minutes
  • • = Ivy method = 1 to 10 minutes
    • = Duke method = 1 to 3 method
• Newborn  = Ivy method  = 1 to 5 minutes
• Child        =  Ivy method  = 1 to 6 minutes

What are the methods for measuring bleeding time?

How will you describe the IVY method?

1. It is the most common method where the lancet is used, ensuring a precise surgical incision with a depth of 1 mm. This will give reproducible results.
2. The Bleeding Time is determined by making a superficial skin incision and timing the duration of blood flow from the wounded area until it stops.

How will you describe the Template method?

1. A puncture of the forearm after having pressure in the upper arm at 40 mm Hg by a blood pressure instrument.
   1. Clean the volar surface of the forearm.
   2. Make an incision using the template, up to a depth of 1 mm. If possible, give two pricks.
   3. Avoid any visible vein.
   4. Now blot the blood till it stops.

• Bleeding time is usually normal in coagulation disorders.
• Bleeding time has limited precision, accuracy, and reproducibility.

What are the causes of longer-than-normal bleeding time?

1. Blood vessel defect.
2. Platelet count may be decreased, or there may be a defect in their function.
3. Thrombocytopenia. The count is <100,000/cmm and usually <80,000/cmm before bleeding becomes abnormal.
   1. Bleeding time is always abnormal when the platelet count is <60,000/cmm.
   2. Platelet count <80,000/cmm = BT is ∼10 minutes.
   3. Platelet count <40,000/cmm = BT is ∼20 minutes.
   4. Platelet count <10,000/cmm = BT is >30 minutes.
4. Disseminated intravascular coagulation (DIC), where the platelets are consumed.
5. Acute Leukemia.
6. Coagulation factor deficiencies, such as Factor I, II, V, VIII, IX, and XI, may show some increase.
7. Hodgkin’s disease.
8. Severe hepatic disease.
9. Hemolytic disease of the newborn.
10. Patients with uremia have a decrease and dysfunction of platelets.
11. Patients with anti-inflammatory drugs like aspirin and indomethacin.
12. In von Willebrand’s disease, the bleeding time is variable. BT is increased out of proportion to platelets, suggesting von Willebrand disease or a platelet functional defect.

When will you see normal bleeding time (BT)?

1. Hemophilia.
2. Severe hereditary hypofibrinogenemia.
3. Severe hereditary hypoprothrombinemia.

• What are the Critical values of the bleeding time?
  •  The bleeding time is usually greater than 15 minutes.

Questions and answers: