Coagulation Screening

Sample

1. If plasma is needed, take 5 ml of venous blood and add sodium citrate as the anticoagulant.
2. Perform the assay immediately or as soon as possible.
3. For factors II, V, VII, and X,  place the citrated plasma on ice immediately, and the sample is stable for 2 hours.
   1. Freeze if it is delayed >2 hours.

Definition of bleeding disorders:

1. Before we start work up of bleeding disorders, we should understand two systems of bleeding.
2. Bleeding disorders may be of two types:
   1. Primary hemostasis, related to:
      1. Platelets.
      2. Vascular defects.
   2. Secondary hemostasis related to:
      1. Coagulation factors defects.

Table to differentiate hemostasis:

Clinical feature	Primary Hemostasis	Secondary Hemostasis
Onset time	Immediately after trauma	Occurs Late after trauma
Clinical presentation	Petechiae Ecchymosis	Hematoma
Sites	Mucous membrane skin	Deep Tissue Joints and muscles CNS
Mucous membranes	Nasal Oral GI Urinary	Less common
Examples	Thrombocytopenia Willebrand disease Platelets defects	Factors deficiency Liver diseases Acquired inhibitors

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 :

1. Idiopathic thrombocytopenia.
2. Low due to drugs.
3. Hypersplenism.
4. 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:

1. Anticoagulant therapy.
2. DIC.
3. Vit. K deficiency.
4. Liver diseases.
5. Rarely dysfibrinogenemia.
6. 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
APTT (Activated partial thromboplastin time) PT (Prothrombin time) TT (Thrombin time)	Abnormal Abnormal Normal	Vitamin K deficiency Liver diseases Factor deficiency in a common pathway  (X, V, II)
APTT PT	Abnormal Normal	Lupus anticoagulant Specific factor inhibitor Factor deficiency in the intrinsic pathway
APTT PT	Normal Abnormal	Specific factor inhibitor Factor deficiency in the extrinsic pathway
APTT PT TT	Abnormal Abnormal Abnormal	Severe liver disease DIC Factor (I) deficiency Potent inhibitor Dysfibrinogenemia Hypofibrinogenemia

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