Clotting Time Procedure : Physiology Practicals

📌 𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦:-   / drgbhanuprakash  

Clotting Time (CT)

Sample For Clotting Time
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Clotting Time is done on a fresh blood sample, and the patient needs to be in the lab.

Indications For Clotting Time
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Clotting Time is advised to find bleeding disorder, most likely due to clotting factors deficiency.
To Diagnose hemophilia.
Because of other tests, it has lost its importance. Clotting time was done by the Lee-white method, but it was cumbersome, insensitive, and nonreproducible.

Definition Of Clotting Time (CT)
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Clotting time (CT) is the time that is required to form the clot. The most commonly used test of clotting time is activated partial thromboplastin time (APTT) and prothrombin time (PT).

Precautions For Clotting Time (CT)
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It does not diagnose mild coagulation disorders.
Blood should be taken in the least traumatic manner.
Must avoid premature activation of the clotting process to ensure an accurate result.
Avoid hemolysis of the sample.

It is essential 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 are needed.
4. Also, consider other contributing or underlying diseases.

Draw-backs of clotting time (CT):
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This is not a reliable test for the screening of bleeding condtions.
It is insensitive to detect mild conditions of bleeding.
It will detect only the severe bleeding condtions.
Normal clotting time does not rule out coagulation abnormalities.
There are many variables in performing the test.
Routine preoperative clotting time and bleeding time have little value for routine preoperative screening for the bleeding, e.g., in the tonsillectomy.

Pathophysiology Of Clotting Time (CT)
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Lee-White Clotting time was used to monitor the heparin therapy, but now it is replaced by the APTT.
For clot formation, prothrombin is converted into thrombin.
Thrombin converts soluble fibrinogen into insoluble fibrin.
For this process, clotting factors are needed, along with calcium.
Also assisted by the factors produced by platelets and damaged tissue.
So clotting time is the time needed for the generation of thrombin from the complex clotting system.
When there is any deficiency in these factors, it will lead to prolonged clotting time.

Normal Clotting Time (CT)
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The expected range is 4 to 10 minutes.
The glass tube method clotting time is 5 to 15 minutes.
Siliconized tube’s clotting time is 19 to 60 minutes (reference: Interpretation of diagnostic test by Jacques Wallach M.D.)
It is rarely used because of the variation; the clotting factors assays are more accurate.

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