and the severity of the bleeding is proportional to the degree

of deficiency. In order to treat the hemorrhagic condition,

it is important to identify and quantify the deficient factor.

Fibroscreen reagent is one such test reagent, which can

identify the deficiency of factor I (fibrinogen). The reagent

is used as a source of thrombin to determine the qualitative

reactivity of fibrinogen.

Reagent

Fibroscreen reagent is a lyophilized preparation of bovine

thrombin of 50 NIH/mL. Reconstitute with 1 mL of distilled

water; wait for 5 minutes, do not shake and mix gently by

swirling till the solution attains homogeneity. Further keep

aside for 10 minutes to attain equilibrium. Gently swirl the

vial while drawing the reagent for use. Once reconstituted

it is ready to use reagent for the thrombin time test.

Storage and Stability

1. Store the unopened reagent vials at 2–8°C. Do not

freeze.

2. The shelf-life of the reagent is as per the expiry date

mentioned on the reagent vial label and carton label.

3. Once reconstituted the Fibroscreen reagent is stable

for 6 days when stored at 2–8°C and for 4 hours

at room temperature (20–25°C), provided it is not

contaminated. Extreme care has to be taken to maintain

aseptic precautions while reconstituting, retrieving

and handling reagents to prevent contamination. The

Fibroscreen reagent vial must be replaced at 2–8°C

immediately upon retrieving the reagent for the day’s

work.

Principle

When a known quality and concentration of Fibroscreen

reagent is added to citrated plasma, by observing the time

required for clot formation and the quality of clot formed,

a qualitative estimation of fibrinogen in the sample can be

obtained.

Note

1. In vitro diagnostic reagent for laboratory and professional use. Not for medicinal use.

2. The reagent contains 0.1% sodium azide as preservative.

3. Fibroscreen thrombin reagent is not from a human

source, hence contamination due to HBsAg, HIV and

HCV is practically excluded.

4. It is very important that absolutely clean and dry

micropipettes be used to aspirate and dispense the

reagent.

5. Avoid exposure of the reagent to elevated temperatures,

direct light and contamination. Immediately replace

cap after use and store at recommended temperature.

Quality Control

A known normal control should be run in parallel with

each batch of tests. This control may be Tulip plasma

coagulation control Plasmatrol-I or freshly drawn normal

plasma.

298 Concise Book of Medical Laboratory Technology: Methods and Interpretations Sample Collection and Preparation

No special preparation of the patient is required prior to

sample collection by approved techniques. Withdraw

blood without undue venous stasis and without frothing

into a plastic syringe fitted with a short needle of 19 to

20 SWG. The venipuncture must be a ‘clean’ one and,

if there is any difficulty, take a new syringe and needle

and try another vein. Transfer the blood into tubes, after

detaching the needle from the syringe. Mix nine parts of

freshly collected blood with one part of sodium citrate

(0.109-M mol/L, 3.2%). Centrifuge immediately for fifteen

minutes at 3000 rpm (approximately 2000 g) and transfer

the plasma into a clean test tube. Plasma must be tested

within 3 hours of collection.

Additional Material Required

10 ×75 mm glass test tubes, 0.2 mL precision pipettes, stopwatch, distilled water, fresh plasma.

Procedure

Bring all the reagents and samples to room temperature

before testing.

Manual Method

Testing should be done in duplicate at room temperature

(20-25°C):

1. To a clean and dry 10 × 75 mm test tube add 0.2 mL

of plasma to be tested and 0.2 mL of the reconstituted

Fibroscreen reagent.

2. Start a stopwatch simultaneously with the addition of

the Fibroscreen reagent.

3. Shake the tube gently to mix the contents and then tilt

the tube back and forth.

4. Note the time at the first appearance of the clot and for

the remaining portion of 60 seconds for consistency

and character of the clot formed.

Interpretation of Results

Normal plasma begins to show clot formation within 15

seconds after Fibroscreen reagent has been added. Because

time of clot formation may be influenced by additional factors