When blood vessel ruptures….• When you get a cut and your blood vessel ruptures, blood

platelets collect at the site of the wound. They create a temporary plug to stop the bleeding. In order to produce a strong blood clot, a series of 12 plasma proteins, or coagulation “factors” act together to make a substance called fibrin, which seals the wound.

• A bleeding disorder known as hemophilia could cause your body to create certain coagulation factor incorrectly, or not at all. Some medications, liver disease, or vitamin K deficiency may cause abnormal clot formation.

• Symptoms of a bleeding disorder include:• easy bruising• bleeding that won’t stop, even after applying

pressure to the wound• heavy menstrual periods• blood in the urine• swollen or painful joints• nosebleeds

• Hemostasis or haemostasis : is a complex process which causes the

bleeding process to stop. It refers to the process of keeping blood within a damaged blood vessel.

Hemostasis is maintained in the body via three mechanisms:

• Vascular spasm - Damaged blood vessels constrict. • Platelet plug formation - Platelets adhere to

damaged endothelium to form platelet plug (primary hemostasis) and then degranulate.

• Blood coagulation - Clots form upon the conversion of fibrinogen to fibrin, and its addition to the platelet plug (secondary hemostasis).

THE CLOTTING MECHANISM

INTRINSIC EXTRINSC

PROTHROMBIN THROMBIN

FIBRINOGEN

FIBRIN(II) (III)

(I)V

X

Tisue ThromboplastinCollagen

VII

XIIXIIXVIII

FIBRINOLYTIC PHASE

• ANTICLOTTING MECHANISMS ARE ACTIVATED TO ALLOW CLOT DISINTEGRATION AND REPAIR OF THE DAMAGED VESSEL.

HEMOSTASIS

• DEPENDENT UPON:

Vessel Wall Integrity Adequate Numbers of Platelets Proper Functioning Platelets Adequate Levels of Clotting Factors Proper Function of Fibrinolytic Pathway

So What Causes Bleeding Disorders?

VESSEL DEFECTS

PLATELET DISORDERS

FACTOR DEFICIENCIES

VESSEL DEFECTS VITAMIN C DEFICIENCY BACTERIAL & VIRAL INFECTIONS ACQUIRED

PLATELET DISORDERS

THROMBOCYTOPENIA (INADEQUATE NUMBER OF PLATELETS)

Causes DRUG INDUCED BONE MARROW FAILURE HYPERSPLENISM OTHER CAUSES

THROMBOCYTOPATHY )ADEQUATE NUMBER BUT ABNORMAL FUNCTION .(

causes UREMIA INHERITED DISORDERS MYELOPROLIFERATIVE DISORDERS DRUG INDUCED(ASPIRIN,)

FACTOR DEFICIENCIES

• Inherited:MOPHILIA A

1. HEMOPHILIA B

2. V W DISEASE

• Acquired:

1. Anticoagulant therapy

2. Liver diseases

3. DIC

LABORATORY EVALUATION

• PLATELET COUNT• BLEEDING TIME (BT)• PROTHROMBIN TIME (PT)• PARTIAL THROMBOPLASTIN TIME (PTT)• THROMBIN TIME (TT)

PLATELET COUNT (CBC)

NORMAL 100,000 - 400,000 CELLS/MM3

< 100,000 Thrombocytopenia

50,000 - 100,000 Mild Thrombocytopenia

< 50,000 Sever Thrombocytopenia

PROTHROMBIN TIMEPROTHROMBIN TIME Measures Effectiveness of the Extrinsic Measures Effectiveness of the Extrinsic

PathwayPathway

NORMAL VALUENORMAL VALUE 10-15 SECS10-15 SECS 11-16 sec depends……..11-16 sec depends……..

PT• The prothrombin time: is therefore the time required for the plasma

to clot after an excess of thromboplastin and an optimal concentration of calcium have been added.

• Measures the function of the Extrinsic Pathway. • Sensitive to Factors I, II, V, VII, X.

• The PT evaluates patients suspected of having an inherited or acquired deficiency in these pathways.

Principles

• When preformed tissue thromboplastin and calcium chloride are added to citrated plasma, the plasma clots. The time taken for the clot to appear is called Prothrombin time (PT).

Procedure

• Requirements.• Patient‘s platelet-poor plasma• Normal, ‗control‘ plasma• Thromboplastin Reagents• Glass Tubes Automatic Micropipettes of 100 μl• A Water Bath set at 37°C Stop watches • A Table Lamp

Performance• Set the table lamp behind the water bath in such a way that the tubes can

be seen against it but the eyes of the scientist are protected from direct light.

• Place four plain glass tubes in the water bath to warm at 37°C.• Deliver 100 μl of test plasma in a test tube and wait for 2 minute. • Deliver 200 μl of commercial tissue thrombo plastin and • start the stopwatch simultaneously. • Mix the contents and leave. After 6-8 seconds, examine the tube against

shielded light for clot formation, by tilting. • Keep on doing so every 1-2 seconds by briefly taking the tube out of the

water. • Stop the stopwatch when a visible clot is formed in the test tube and

note the time. • Repeat the procedure once again on the test plasma. Take the mean of

the two recorded times. Repeat the test on the control plasma as done for the patient‘s plasma

Precautions:

• The blood should be collected through a clean venipuncture & without much stasis.

• The proportion of anticoagulant and blood should be precise and appropriate.

• The samples should not be allowed to stand at room temperature for too long.

• If a delay is expected, these should be transported on crushed ice.

• The platelet-poor plasma should be separated as soon as possible.

• The blood should be collected and processed using disposable plastic syringes, tubes and pipettes.

• The test should always be performed in clean glass tubes.

• The results are also reported as a ratio between the patient‘s Prothrombin Time & that of the test plasma or as INR.

• Interpretations: • Prothrombin Time is prolonged in deficiency of

Factors II, V, VII and X as well as in the presence of Heparin. This can occur in the following conditions: Oral anticoagulant therapy (Vitamin K antagonists) Obstructive jaundice Liver disease Haemorrhagic disease of the newborn Malabsorption Vitamin K deficiency Hereditary deficiency of concerned

PT RESULTPTT RESULTEXAMPLES OF CONDITIONS THAT MAY BE PRESENT

ProlongedNormalLiver disease, decreased vitamin K, decreased or defective factor VII, chronic low-grade disseminated intravascular coagulation (DIC), anticoagulation drug (warfarin) therapy

NormalProlongedDecreased or defective factor VIII, IX, XI, or XII, von Willebrand disease (severe type), presence of lupus anticoagulant, autoantibody against a specific factor (e.g., factor VIII)

ProlongedProlongedDecreased or defective factor I, II, V or X, severe liver disease, acute DIC, warfarin overdose

NormalNormal or slightly prolongedMay indicate normal hemostasis; however, PT and PTT can be normal in conditions such as mild deficiencies in coagulation factor(s) and mild form of von Willebrand disease. Further testing may be required to diagnose these conditions.

nterpretation of PT and PTT in Patients with a Bleeding or Clotting Syndrome

THE CLOTTING MECHANISM

INTRINSIC EXTRINSC

PROTHROMBIN THROMBIN

FIBRINOGEN

FIBRIN(II) (III)

(I)V

X

Tisue ThromboplastinCollagen

VII

XIIXIIXVIII

When is it ordered?

• Used to monitor oral anticoagulant therapy (Warfarin / Coumadin).

• When a patient who is not taking anti-coagulant drugs has signs or symptoms of a bleeding disorder.

• When a patient is to undergo an invasive medical procedure, such as surgery, to ensure normal clotting ability.

An elevated prothrombin time may indicate the presence of:

Vitamin K deficiency(Vitamin K is needed to make prothrombin and other clotting factors)

DIC liver disease a deficiency in one or more of the following factors: I, II, V, VII, X. Anticoagulant (warfarin)

INR• A PT test may also be called an INR test.• INR (international normalized ratio) stands for a way of

standardizing the results of prothrombin time tests, no matter the testing method.

• So your doctor can understand results in the same way even when they come from different labs and different test methods.

• Using the INR system, treatment with (anticoagulant therapy) will be the same. In some labs, only the INR is reported and the PT is not reported

INR• An INR of 1.0 means that the patient PT is normal.• An INR greater than 1.0 means the clotting time is

elevated.• INR of greater than 5 or 5.5 = unacceptable high risk of

bleeding,whereas if the INR=0.5 then there is a high chance of having a clot.

• Normal range for a healthy person is 0.9–1.3, and for people on warfarin therapy, 2.0–3.0, although the target INR may be higher in particular situations, such as for those with a mechanical heart valve.

PARTIAL THROMBOPLASTIN TIME

Measures Effectiveness of the Intrinsic Pathway

NORMAL VALUENORMAL VALUE 25-40 SECS25-40 SECS