4. Bleeding Time
- Test used to diagnose bleeding disorders
- Measures how fast the bleeding stops
- It assesses platelet function
Methods:
1. Duke’s method
2. Ivy’s method
5.
6.
7. Duke’s method
Equipment: lancet, cotton, filter paper, spirit, stopwatch
Procedure:
- Sterilise finger tip with spirit, allow to dry
- Prick sufficiently deeply, so blood comes out without
squeezing
- Note the time when bleeding starts
8. - Mop the blood by touching the finger tip with the
filter paper
- Repeat every 15 seconds, each time using a fresh
portion of the paper till bleeding stops
- Note the time
9.
10. Normal BT: 1-9 minutes
Prolonged BT seen in:
- Thrombocytopenia
- Platelet disorders
- Coagulation disorder; Von Willebrand disease
- Blood vessel disorders
12. Clotting time
- It is the time required for the blood to coagulate
- It is a test of coagulation factor function
Methods:
1. Capillary tube method(Wright’s method)
2. Venepuncture method(Modified Lee and White
method)
13. Capillary tube method
Equipment: capillary tube, cotton, spirit, lancet, stopwatch
Procedure:
- Sterilise finger tip with spirit, allow to dry
- Prick sufficiently deeply, so blood comes out without
squeezing
- Note the time when bleeding starts
- Touch the blood drop using one end of the capillary tube
tilted downwards
14. - It gets filled via capillary action
- After 2 minutes, start breaking off small lengths of
the tube, at intervals of 15 seconds and look for a
fibrin thread between the snapped ends
- Note the time when the fibrin thread is first seen
15.
16.
17. Normal CT: 3-10 minutes
Prolonged CT is seen in:
- Hemophilia
- Vitamin K deficiency
- Liver diseases
- DIC
- Overdosage of anticoagulants
19. Prothrombin time
- Measures the time taken by plasma to clot
- Test of the extrinsic pathway of coagulation
- PT reveals deficiency of factors 2, 5, 7, 10 or
fibrinogen
20. Procedure
- Blood sample collected and anti-coagulant
added(oxalate)
- Calcium and tissue factor is added to test CT, which
activates extrinsic pathway of coagulation
- Calcium and tissue factor activates clotting factors to
convert prothrombin into thrombin
- Time taken for blood to coagulate is recorded - this is
prothrombin time
21. Normal PT: 9-12 seconds
Prolonged PT seen in:
- Deficiencies of clotting factors, like factor
VIII(hemophilia A), factor IX(hemophilia B), factor
XI(hemophilia C)
- VWD
23. International Normalised Ratio(INR)
- Used to assess therapeutic effect of warfarin
- It is the ratio of PT of the patient to normal control
Normal values:
- In healthy people - <1.1
- Patients taking warfarin - 2.0-3.0
24. References:
● Dr. Purnima S. Rao - Textbook of Pathology & Genetics For
Nursing
Questions:
salman.s.ansari92@gmail.com
