Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)

-
    Prothrombin Time (PT):

    Prothrombin time (PT) is a blood test that measures how long it takes blood to clot. Prothrombin time test can be used to check for bleeding problems. PT is also used to check whether medicine to prevent blood clots is working.

PT test may also be called an INR test. INR (international normalized ratio).

Prothrombin Time asses coagulation factors in extrinsic pathway (Factor VII) and common pathway (Factor X, V, II, I).

    Principle:
Tissue Thromboplastin and calcium are added to plasma and clotting time is determined. The test determines the overall efficiency of extrinsic and common pathway.

    Procedure:
  1. 0.1 ml of plasma in a glass tube kept in water bath at 37 degree Celsius.
  2. Add 0.1 ml of Thromboplastin reagent and mix.
  3. After 1 minute, add 0.1 ml of calcium chloride solution. 
    Immediately start the stopwatch and record the time required for clot formation.
    Normal Range : 11-16 seconds.

    Clinical Significance:
  • DIC
  • Liver Disease
  • Vitamin K deficiency
  • Oral Anticoagulant Therapy
  • Factor V,VII,X deficiency

        Activated Partial Thromboplastin Time (APTT):
Also known as Partial thromboplastin Time (PTT), Kaolin Cephalin Clotting Time (KCCT)
Is a performance indicator measuring the efficacy of both the intrinsicpathway (FactorXII,XI, IX,VIII) and common pathway(Factor X,V,II,I).
APTT is the most widely used method for monitoring intravenous heparin anticoagulant therapy (Heparin acts to accelerate Antithrombin which inhibits the action of thrombin).

    Principle:        Plasma is incubated with an activator Phospholipid and calcium, Clotting time is measured.

    Procedure:
  1. Mix equal volume of phospholipid reagent and calcium chloride solution in a glass test tube and keep in a water bath at 37 degree Celsius.
  2. deliver 0.1 ml of plasma in another test tube and add 0.1 ml of Kaolin solution. Incubate at 37 degree celsius in the water bath for 10 minutes.
  3. After exactly 10 minutes, add 0.2 ml of phospholipid calcium chloride mixture.Start the stopwatch and record the clotting time.
    Normal Range: 30-40 seconds

    Clinical Significance:
  • DIC
  • Hemophilia A and B.
  • VWD
  • Liver Disease.
  • Massive transfusion of Whole Blood.
  • Administration of heparin.
  • Factor IX,XI,XII deficiency.


Comments

Post a Comment

If you have any doubts, please let me know.

Popular posts from this blog

Histopathology Technique - Part 2 (Tissue processor)

-
Image
Tissue Processing:       Nowadays all the process of fixation, dehydration, clearing, and impregnation are carried out in a special equipment which is known as automated tissue processor. It can be a open (hydraulic) system or a closed (Vacuum) type. In the open type, the tissue processor has 12 - 16 glass jars for formalin, ascending grades of alcohol, xylene and thermostatically- controlled two paraffin wax baths to keep paraffin wax in molten state. Tissue moves automatically by hydraulic mechanism from one jar to another after fixed time schedule and the whole process takes 16-22 hours. In closed type of tissue processor, tissue cassettes are placed in a single container while different processing fluids are moved in and out sequentially according to electronically programmed cycle. The closed or vacuum  processor has the advantage that there is no hazard of contamination of the laboratory by toxic fumes unlike in open system. In addition, heat and ...
Read more

Bleeding Time and Clotting Time

-
Image
Introduction: For the investigation of a case of bleeding disorder,clinical history is very important. An accurate clinical and family history will often give an important time-saving clue to the nature of underlying bleeding disorder. 􀂄 Appearance of purpuric spots or bruises over minimally injured surface suggests an abnormality of the vascular wall. 􀂄 Continuous bleeding from mucous membranes, cuts, wounds, deeper haematomas or bleeding into the joints will suggest a defect in the blood coagulation system. 􀂄 Excessive bleeding following delivery, or retention of dead foetus, or oozing following extensive surgery, suggest the possibility of fibrinogen depletion or presence of circulating anticoagulant agents. 􀂄 History should also be taken about the ingestion of antiplatelet drugs such as aspirin. Two of the commonly used screening tests, bleeding time and whole blood clotting time, are discussed below. BLEEDING TIME  (BT) Bleeding time is duration of bleeding from a standard...
Read more

BONE MARROW EXAMINATION

-
Image
  BONE MARROW EXAMINATION It is the only method of correctly diagnosing diseases of blood. Sites of bone marrow aspiration: The following sites are selected for bone marrow aspiration: Sternum Iliac crest and upper end of tibia in children. Requirements: A special bone marrow needle (salah or klima needle) along with stilette Local anesthesia (Lignocaine) 2 to 5 ml syringe Glass slides Absolute methanol Formal ethanol Procedure: The site of puncture is usually sternum. Sterilize the selected site with soap water, iodine and finally with alcohol. The Site is anesthetized locally using lignocaine. Skin and subcutaneous tissues are punctured using sterilized bone biopsy and needly. When needle reaches periosteum, guarded needle is pushed further about 5 mm. Now the needle is fixed tightly in position. Now the needle is further pushed with boring motion into the cavity of bone. The stilette is removed and well fitted 2-5 ml syringe is used About 0.3 ml of bone marrow contents are sucke...
Read more