Clotting Time (C T)

Sample

• Clotting Time is done on a fresh blood sample, and the patient needed to be in the lab.

Indications

1. Clotting Time is advised to find bleeding disorder, most likely due to clotting factors deficiency.
2. To Diagnose hemophilia.

Precaution

1. It does not diagnose mild coagulation disorders.
2. Blood should be taken in the least traumatic manner.
3. The premature activation of the clotting process must be avoided to ensure an accurate result.
4. Avoid hemolysis of the sample.
5. It is important to get the history of the patient:
   1. Note physical appearance, site, the severity of the disease, and frequency of the bleeding episodes.
   2. Get an accurate history of the drugs.
   3. A patient and the family history in detail needed.
   4. Also, consider other contributing or underlying diseases.

Pathophysiology

1. For the clot formation, prothrombin is converted into thrombin.
2. Thrombin converts soluble fibrinogen into insoluble fibrin.
3. For this process, clotting factors are needed, along with calcium.
4. Also assisted by the factors produced by platelets and damaged tissue.
5. So clotting time is the time needed for the generation of thrombin from the complex system of clotting.

6. When there is any deficiency in these factors, it will lead to prolonged clotting time.
7. It is rarely used because of the variation; instead, the clotting factors are more accurate.

Procedure

1. Two methods can estimate clotting time:
   1. Capillary method.
      1. Prick the finger with the lancet.
      2. Hold the capillary over the blood and the capillary will fill automatically.
      3. Now, after regular intervals break the capillary.
      4. When a clot starts forming that is the endpoint and clotting time.
         

         Clotting time capillary method

   2. Test tube method.
      1. Perform this test at 37 ° C.
      2. For the tube method, take 4 ml of blood and start the time.
         1. Note the time when there is the first appearance of the clot formation.
      3. This test can be done in multiple tubes to be more accurate.
         

         Clotting time tubes test

Normal

• The expected range is 4 to 10 minutes.
• The glass tube method clotting time is 5 to 15 minutes.
• Siliconized tubes clotting time is 19 to 60 minutes.

Causes of prolonged clotting time are:

1. Coagulation factors deficiencies which may be:
   1. Congenital.
   2. Acquired.
2. Drugs like heparin and thrombin inhibitor.

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