Haemostasis Lecture notes


B). Acquired coagulation disorders



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B). Acquired coagulation disorders

These include cases such as vitamin K deficiency, severe liver diseases ie cirrhosis and disseminated intravascular coagulation associated with infections, obstetric complications such as septic abortion, HDNB, snake envenormation and malignancies. They also include overdose of anticoagulants such as warfarin



Laboratory tests to Investigate Haemostatic mechanism

1). Total blood count/platelet count

Normal range 150-400×109/L

Platelet count is usually reduced in haemostatic disorders.


2). Peripheral blood film (PBF) examination. Characterized by lower platelet distribution and appearance of giant platelets.
Screening test

1). Bleeding time- It tests for platelets and platelet function. It is performed by either Ivy’s method (range 2-7 minutes) or by Dukes method.

Always prolonged in bleeding disorders.
2). Activated partial thromboplastin time (APTT)

It assesses the integrity of the intrinsic pathway of coagulation cascade.

Normal range 36-50 seconds

It is used in monitoring patients being treated with warfarin

It is prolonged in:


  1. DIC involving several clotting factors

  2. Deficiency of clotting factors V, II, and IX, X, XI or XII.

  3. Vitamin K deficiency, liver diseases, heparine/warfarin anticoagulant

3). Prothrombin Time (PT)

It assesses the integrity of the extrinsic pathway of coagulation cascade

Normal range 11-16 seconds

It is used in monitoring patients being treated with warfarin

It is prolonged in:



  1. Treatment with oral anticoagulant drugs (vitamin K antagonist eg warfarin.

  2. Liver disease

  3. DIC

  4. Haemolytic disease of the new born (HDNB)

  5. Deficiency of factor VII, X, V or prothrombin.

4). Thrombin Time (TT)

It assesses the integrity of the common pathway of coagulation cascade

Normal range 12-15 seconds

It is prolonged in:


  1. DIC and other conditions which produce low levels of fibrinogen.

  2. Abnormal fibrinogen.

  3. Treatment with heparin

  4. Liver failure

5). International Normalized Ration (INR)


An INR test measures the time for your blood to clot. It is also known as prothrombin time, or PT. It is used to monitor blood-thinning medicines, which are also known as anticoagulants. The INR, or international normalized ratio, can also be used to check if you have a blood clotting problem.

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