Coagulation:- part 2 – Coagulation Screening, Work up of Bleeding Disorder
Coagulation Screening
Sample
- If plasma is needed, take 5 ml of venous blood and add sodium citrate as the anticoagulant.
- Perform the assay immediately or as soon as possible.
- For factors II, V, VII, and X, place the citrated plasma on ice immediately, and the sample is stable for 2 hours.
- Freeze if it is delayed >2 hours.
Definition of bleeding disorders:
- Before we start work up of bleeding disorders, we should understand two systems of bleeding.
- Bleeding disorders may be of two types:
- Primary hemostasis, related to:
- Platelets.
- Vascular defects.
- Secondary hemostasis related to:
- Coagulation factors defects.
- Primary hemostasis, related to:
Table to differentiate hemostasis:
Clinical feature | Primary Hemostasis | Secondary Hemostasis |
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Onset time |
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Clinical presentation |
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Sites |
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Mucous membranes |
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Examples |
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The Coagulation Screening profile consists of:
1. Platelets.
2. Bleeding time.
3. Clotting time.
4. APTT.
5. PTT.
6. PT.
7. Clotting factor assay.
Platelets abnormality is seen in :
- Idiopathic thrombocytopenia.
- Low due to drugs.
- Hypersplenism.
- SLE.
- (See more in Platelets)
Abnormal PTT alone is seen in:
- Bleeding due to a defect in factors VIII, IX, and XI (8, 9, 11).
Abnormal PT alone is seen in:
- Bleeding due to a defect in Factor VIII (8).
Abnormal PTT + PT is seen in:
- Anticoagulant therapy.
- DIC.
- Vit. K deficiency.
- Liver diseases.
- Rarely dysfibrinogenemia.
- Rarely due to factor X, V, and II defects.
Interpretations of the blood coagulation screening profiles:
Coagulation tests | Result of coagulation tests | Causes of possible diseases |
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Coagulation screening for bleeding disorders:
Coagulation screening test | Cause of the disease | Possible mechanism |
Prothrombin test (PT) |
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Deficiency or inhibitors of:
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Thrombin test (TT) |
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Deficiency or abnormality of:
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Activated partial thromboplastin test (APTT) |
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Deficiency or inhibitors:
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Fibrinogen |
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